MIDWEST RESEARCH INSTITUTE
MRI
EPORT
A STUDY OF THE EFFICIENCY OF THE USE OF
PESTICIDES IN AGRICULTURE
Midwesf Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
VOLUME II
RvR Consultants
6400 Hodges Drive
Shawnee Mission, Kansas 66208
FINAL REPORT
July 1975
Contract No. 68-01-2608
MRI Project No. 3949-C
For
Environmental Protection Agency
Strategic Studies Unit, OPP (HM568)
401 M Street, N.W.
Waterside Mall, Room 507
Washington, D. C. 20460
Attn: Mr. Allan Zipkin
Project Officer
MIDWEST RESEARCH INSTITUTE 425 VOLKER BOULEVARD, KANSAS CITY, MISSOURI 64110 • 816561-0202
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MRI-NORTH STAR DIVISION 3100 38th Avenue South, Minneapolis, Minnesota 55406* 612 721-6373
MRI WASHINGTON, D.C. 20005-1522 K STREET, N.W. • 202 293-3800
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A STUDY OF THE EFFICIENCY OF THE USE OF
PESTICIDES IN AGRICULTURE
VOLUME II
By
Gary L. Kelso
with
Rosmarie von Riimker
Kathryn A. Lawrence
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
RvR Consultants
6400 Hodges Drive
Shawnee Mission, Kansas
66208
FINAL REPORT
July 1975
Contract No. 68-01-2608
MRI Project No. 3949-C
For
Environmental Protection Agency
Strategic Studies Unit, OPP (HM568)
401 M Street, N.W.
Waterside Mall, Room 507
Washington, D.C. 20460
Attn: Mr. Allan Zipkin
Project Officer
INSTITUTE 425 VOLKER BOULEVARD, KANSAS CITY, MISSOURI 64110 ° 816561-0202
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PREFACE TO VOLUME II
This report describes the results of a study conducted jointly by
Midwest Research Institute (MRI) and RvR Consultants during the period
1 August 1974 to 14 February 1975. The study was performed for the Stra-
tegic Studies Unit, Office of Pesticide Programs, U.S. Environmental
Protection Agency (EPA), under Contract No. 68-01-2608, entitled "A
Study of Wasteful Pesticide Use Patterns." The EPA Project Officer was
Mr. Allan Zipkin.
Work on this program (MRI Project No. 3949-C; RvR Project No. 67)
was conducted with Dr. Rosmarie von Rumker as task leader. The program
was under the general supervision of Dr. H. M. Hubbard, Director of
MRI's Physical Sciences Division, and Dr. E. W. Lawless, Head, Tech-
nology Assessment Section. The MRI project members consisted of Mr. Gary
Kelso, Group Leader; Miss Kathryn Lawrence; and Mr. Francis Bennett.
Dr. Arthur Allen acted as consultant to the program. The RvR project
members were Dr. Rosmarie von Rumker and Mrs. Freda Moray.
Approved for:
LOWEST R SEARCH INSTITUTE
. M. HubDard, Director
Physical Sciences Division
2 July 1975
iii
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CONTENTS - VOLUME II
List of Figures x
List of Tables xii
Abstract 1
Sections
I INTRODUCTION 3
II SUMMARY : . . . 4
III PESTICIDE WASTES AND LOSSES OCCURRING DURING
APPLICATION 11
Introduction 11
Typical Pesticide Applications Used in
Agriculture 12
Dust Applications 12
Granular Applications 13
Spray Applications. . 14
Pesticide Overapplication and Nonuniform
Distribution. 19
Physical Equipment Problems 20
Metering Devices. . 20
Nozzles 22
Spray Tank Agitation 25
Operational Equipment Problems 27
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CONTENTS - VOLUME II (continued)
Equipment Calibration 27
Forward Speed of the Unit 28
Height of the Spray Boom 28
Improper Pesticide Formulation 29
Aircraft Spray Distribution 29
Quantification of Overapplication and
Nonuniform Distribution 29
Pesticide Drift 32
General Drift Parameters . 33
Particle Properties . 33
Particle Density. . . . . 33
Particle Shape 33
Particle Size 34
Meteorological Conditions . 38
Wind Direction and Velocity . 38
Turbulence 39
Relative Humidity and Air Temperatures. . 39
Atmospheric Stability 41
Specific Drift Parameters ... 41
Sedimentation and Impaction 42
Sedimentation and Drift 43
Impaction and Drift 46
Spray Particle Size Spectrum 52
Spray Particle Evaporation 57
Drift Potential Quantified 61
Solid Formulations 62
Spray Formulations 62
Likelihood of Pesticide Drift in Agriculture. 65
Agricultural Applications of Pesticides
and Drift . . . 65
vi
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CONTENTS - VOLUME IT (continued)
Page
Dust Applications 66
Granular Applications 68
Spray Applications. 70
Ground Equipment 70
Field Crops 70
Orchards 74
Aerial Equipment 77
Drift From Agricultural Pesticide Applica-
tions - Quantities 81
Estimated Pesticide Losses Due to Drift From
the U.S. Corn, Sorghum, and Apple Crops
(1971) , 83
Estimated Pesticide Drift Losses From the
U.S. Corn Crop (1971) 84
Herbicides and Insecticides 85
Fungicides 93
Other Pesticides 93
Estimated Pesticide Drift Losses From the
U.S. Sorghum Crop (1971) 93
Herbicides 93
Insecticides 95
Fungicides 95
Other Pesticides 98
Estimated Pesticide Drift Losses From the
U.S. Apple Crop (1971) 98
Herbicides 98
Insecticides 98
Fungicides 99
Other Pesticides 99
References to Section III 101
vii
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CONTENTS - VOLUME II (continued)
IV PESTICIDE LOSSES AFTER APPLICATION AND BY
MISCELLANEOUS DISCHARGES 104
Introduction 104
Pesticide Loss Due to Runoff and Soil Erosion . 104
Field Crop Runoff and Soil Erosion 105
Soil Properties 106
Slope Characteristics 107
Land Cover Conditions 107
Rainfall Characteristics 107
Conservation Treatment 107
Management Practice in Field Crops. ..... 107
Pesticide Losses in Runoff and Soil Erosion . 112
Estimated Runoff From the U.S. Corn and
Sorghum Crops - Quantities . 119
Method 1 - Average Seasonal Runoff 119
Method 2 - Rainfall Statistics 123
Methods 1 and 2 Compared 129
Estimated Pesticide Losses From the U.S. Corn,
Sorghum, and Apple Crops (1971) -
Quantities 133
Herbicides 134
Insecticides 137
Fungicides 139
Other Pesticides. . 139
Miscellaneous Pesticide Discharges. 140
Pesticide Spills 140
Pesticide Disposal . 141
References to Section IV 144
Vlll
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CONTENTS - VOLUME II (continued)
Appendix A - Field Studies on Pesticide Drift During
Application 147
Appendix B - Field Studies on Pesticide Runoff After
Application 167
Appendix C - Pesticide Usage on the U.S. Corn, Sorghum,
and Apple Crops (1971) 178
Appendix D - Pesticide Application Rates Recommended by
the USDA and Manufacturers' Product
Labels 195
Appendix E - Extension Service Recommended Pesticide
Application Rates for Apples, Corn, and
Sorghum in Selected States 213
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FIGURES
No. Page
1 Flow increase due to nozzle wear, when spraying a
typical wettable powder formulation 24
2 Decrease in application rate of a wettable powder with
time, sprayed from a tank with no agitation 26
3 Spray distribution at a 2-ft flight level from evenly
spaced nozzles on a high-wing monoplane 30
4 Spray distribution from unevenly arranged nozzles (none
in the center boom section) on a high-wing monoplane
at a 1- to 2-ft flight level 30
5 Spray-distribution curves for applications at a 2-ft
flight level from 30 evenly spaced nozzles on a
Stearman biplane 31
6 Efficiency of impaction of small droplets upon cylinders
at speeds of 1 and 4 m/sec 48
7 Effect of droplet size and velocity of approach upon the
dynamic catch of two sizes of cylinders 49
8 Evaporation rate of water droplets 59
9 Vortex patterns in the wake of a passing high-wing
monoplane 79
10 Vortex patterns in the wake of a helicopter 79
11 Persistence of individual pesticides in soils 114
x
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FIGURES (concluded)
No.
12 Average annual runoff „ 121
13 Average seasonal runoff, percent of total annual runoff,
spring months—April, May, and June 122
14 Mean total precipitation (inches), April, by state
climatic divisions 126
15 Mean total precipitation (inches), May, by state
climatic divisions 127
16 Mean total precipitation (inches), June, by state
climatic divisions. 128
C-l Farm production regions „. 180
C-2 U.S. corn acreage (1971), by state. 181
C-3 U.S. sorghum acreage (1971), by state 186
C-4 U.S. commercial apple production (1971), by state .... 189
XL
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TABLES
No.
1 Likelihood of pesticide drift during crop treatment in
agriculture by method of application .
2 Estimated losses during and after application of pesti-
cides to corn, sorghum, and apples (1971) 8
3 Lifetime and fall of water drops through air 40
4 Terminal velocities of particles in air 44
5 Time required for a solid particle to fall a given
distance (sp. gr. - 2.5) 45
6 Time required for a particle to fall a given distance
(sp. gr. = 1.0) 45
7 Theoretical distance solid particle would drift in 5 and
3 mph winds from a height of 20 and 10 ft, respectively. 47
8 Impaction efficiencies and drift potential of particles
in 3 to 5 mph winds on a 1/2-in. cylinder 51
9 Drop size distribution (cumulative percent by volume
below sizes shown) 53
10 Droplet size distribution of oil droplets sprayed from
a fern-type nozzle 54
11 Variation of droplet size with nozzle type and phase
ratio of 0/W and W/0 emulsions 55
xii
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TABLES (continued)
No.
12 Various nozzles, droplet size VMD's, and spray
distribution patterns formed under laboratory
conditions at stated pressures 56
13 Water droplet size VMD's and droplet spectrums
produced in certain agricultural operations as
a function of nozzle type, pressure, and applica-
tion rate 58
14 Spray particles sizes at emission that drift due
to evaporation. 60
15 Drift potential as a function of solid particle
size and height of release at given meteorological
conditions 63
16 Drift potential as a function of initial drop size,
height of release, and evaporation 63
17 Estimated drift potential of aircraft spray as a
function of spray drop VMD at emission and height
of release -. 64
18 Estimated drift potential of granular pesticide
applications 69
19 Typical operating parameters, droplet size VMD's,
and droplet size spectrums encountered in field
crop spray applications ....... 71
20 Calculated deposit rates (?<,) of various drop size
ranges applied by ground equipment under condi-
tions of neutral or small temperature gradient
in 3 to 5 mph winds 73
21 The likelihood of drift in ground equipment spray
applications 73
22 Likelihood of drift from airblasters. 76
23 Likelihood of pesticide drift during crop treatment
in agriculture by method of application 82
xiii
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TABLES (continued)
No.
24 Pesticide application to corn, by applicator,
1971 86
25 Pesticide application to corn, by method, 1971. ... 89
26 Estimated herbicide drift losses from the U.S. corn
crop (1971) 91
27 Estimated insecticide drift losses from the U.S.
corn crop (1971) 94
28 Estimated herbicide drift losses from the U.S.
sorghum crop (1971) 96
29 Estimated insecticide drift losses from the U.S.
sorghum crop (1971) 97
30 Estimated insecticide drift losses from the U.S.
apple crop (1971) 100
31 "P" values for contouring, contour stripcropping,
and terracing . 109
32 Effects of different cropping systems on runoff and
erosion Ill
33 Period of time after application in which pesticides
are subject to runoff losses . 116
34 Estimated concentration of pesticides in runoff . . . 117
35 Summary of pesticide losses determined from field
studies in Appendix B 118
36 Percent pesticide loss from crops as a percent of
the total amount applied 120
37 Estimated corn crop runoff in April, May, and June
(Method One) 124
38 Estimated sorghum crop runoff in April, May, and
June (Method One) 125
xiv
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TABLES (continued)
No. Page
39 Estimated corn crop runoff in April, May, and
June (Method Two) 130
40 Estimated sorghum crop runoff in April, May, and
June (Method Two) 131
41 Comparison of Methods 1 and 2 132
42 Estimated loss of selected herbicides in runoff and
soil erosion from the U.S. corn and sorghum crops
(1971). 136
43 Estimated loss of selected insecticides in runoff
and soil erosion from the U.S. corn crop (1971) . . 138
A-l Aircraft spray drop size range, use and approximate
recoveries 150
A-2 Percentage on-target deposit of aerially applied
insecticides 151
A-3 Time of application versus target deposit and drift . 153
A-4 Percentage pesticide recovery in a 100-ft target
area 155
A-5 Percent recovery of methyl parathion on ground im-
paction sheets 157
A-6 Estimated percentage spray recovery in the Swath
Zone to 0.375 miles downwind 159
A-7 Application data: afternoon application of meth-
oxychlor from both a mist blower and aircraft . . . 159
A-8 Summary of results from paired field studies of
drift 163
A-9 Spraying conditions and proportion of total leaf
deposit from direct application and drift 165
xv
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TABLES (concluded)
No. Page
C-l Pesticide usage on U.S. corn crop in 1971 by
region 182
C-2 Herbicides used on corn, by region, 1971 (1,000 Ib) . 183
C-3 Insecticides used on corn, by region, 1971
(1,000 Ib) 184
C-4 Miscellaneous pesticides used on corn, by region,
1971 (1,000 Ib) 185
C-5 Pesticide usage on U.S. sorghum crop in 1971 187
C-6 Herbicides used on sorghum, by region, 1971
(1,000 Ib) 188
C-7 Pesticide usage on U.S. apple crop in 1971 by
region 190
C-8 Fungicides used on apples by region, 1971 (1,000 Ib). 191
C-9 Insecticides used on apples by region, 1971
(1,000 Ib) 192
C-10 Herbicides used on apples by region, 1971 (1,000 Ib).. 193
C-ll Miscellaneous pesticides used on apples by region,
1971 (1,000 Ib) 194
D-l USDA recommended pesticide application rates 196
D-2 Pesticides most commonly used on apples; application
rates recommended on product labels 200
D-3 Pesticides most commonly used on corn; application
recommended on product labels 204
D-4 Pesticides most commonly used on sorghum; application
recommended on product labels 209
xv i
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CONTENTS - VOLUME I
Sections
I Introduction
II Definition and Identification of Pesticide Wastes and Losses
III Summary
IV Conclusions and Recommendations
V Pesticide Use Patterns on Corn
VI Pesticide Use Patterns on Sorghum
VII Pesticide Use Patterns on Apples
VIII Wastes and Losses Occurring During and After Pesticide Application
Appendix - Criterion Scheme for the Selection of Survey Crops
xvii
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ABSTRACT
A study was made of the efficiency of the use of pesticides to
identify and quantify the wastes and losses which occur in the treat-
ment of agricultural crops. The study was reported in two volumes. The
first volume identified the management practices and decisions for three
crops—corn, sorghum, and apples—that may lead to wasteful pesticide
use, and quantified the pesticide wastes occurring on each crop as a re-
sult of these management practices. The second volume identified the
physical factors that cause pesticide waste and losses both during and
after crop treatment for agriculture in general, and estimated the ap-
plication and postapplication pesticide losses and wastes that occurred
in 1971 for each of the three above crops. The physical factors which
were examined extensively in this study were pesticide overapplication
and nonuniform distribution, pesticide drift, and pesticide losses from
crops due to runoff and soil erosion.
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SECTION I
INTRODUCTION
Volume II of this report presents the detailed study of the appli-
cation, postapplication, and miscellaneous losses of pesticides in agri-
culture which result primarily from physical factors and techniques, as
opposed to the pesticide losses which result primarily from use practices
(management decisions) that were presented in Volume I. This material is
presented in a separate volume since it is both voluminous and technical
in nature. Readers that are most interested in the technical aspect of
pesticide application and postpesticide application losses will find this
volume particularly suited to their needs.
This volume is divided into two major sections. The first section
examines the pesticide wastes and losses that can occur during applica-
tion; pesticide overapplication, nonuniform distribution, and drift are
the topics covered. The second section examines pesticide losses that
can occur after application and by miscellaneous discharges. Pesticide
runoff and soil erosion are examined extensively, and losses from spills
and disposal techniques are briefly discussed. The discussions in both
sections first describe agricultural practices in general. Following
these general discussions, the losses that occurred during 1971 by pes-
ticide drift and postapplication (by runoff and soil erosion) are esti-
mated in detail for the herbicides, insecticides, fungicides, and other
pesticides used on the three crops—corn, sorghum, and apples--chosen
for intensive study on this project (see Volume I).
A general summary of this part of the project is given in Section
II. Literature references are given at the end of each section. Appen-
dices A through E summarize details of field studies of drift and runoff,
pesticide use on the study crops, and a survey of recommended application
rates.
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SECTION II
SUMMARY
The topics of discussion and findings on pesticide wastes and
losses during and after application are summarized below. The material
covered in this volume of the study deals with agriculture in general
and is not limited to corn, sorghum, and apples (except when quantities
of pesticides lost or wasted are determined). Many of the findings may
apply to other crops to which pesticides are applied in a similar manner.
Each topic discussed in Sections III and IV of this volume is sum-
marized below and the major findings of each topic are given.
PESTICIDE WASTES AND LOSSES OCCURRING DURING APPLICATION
The waste of pesticides at the time of application is a result of
two major mechanisms: overapplication and nonuniform distribution. Loss
of pesticides at the time of application are primarily a result of pes-
ticide drift away from the target area. Both the waste and loss potential
of pesticides during application through these mechanisms are discussed
below.
Waste Potential During Application
Waste during application may result from overapplication or nonuni-
form distribution of pesticides during crop treatment. Overapplication
is defined as physically applying pesticides at a rate higher than that
intended. Nonuniform distribution means distributing the pesticide un-
evenly so that some areas of the field receive heavy dosages of pesti-
cide while other areas receive light dosages. These mechanisms are.two
primary contributors to pesticide waste in agriculture during crop treat-
ment .
Both overapplication and nonuniform distribution are caused by
faulty equipment characteristics and/or erroneous equipment operation.
Some of the physical elements of pesticide application equipment that af-
fect the application rate and the uniformity of chemical disbursement are
the metering devices, nozzles, and spray tank agitation systems. Some of
4
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the more common errors made in operating the application equipment are
improper calibration, uneven driving speeds, improper spray-boom height,
and choice of unsuitable pesticide formulations. The unique problems of
nonuniform aircraft spray disbursement patterns involve both technical
and operational aspects.
Overapplication results from:
* Faulty metering devices.
* Nozzle wear with wettable powder sprays.
* Improper equipment calibration.
* Driving too slow when turning around, encountering obstacles, or
driving up a slope.
* Pesticide formulations mixed in a higher concentration than in-
tended.
Nonuniform distribution results from:
* Faulty metering devices.
* Clogged nozzles.
* Improper spray atomization.
* Inadequate tank agitation systems when spraying emulsions or wet-
table powders.
* Uneven driving speeds,
* Improper spray boom height, either too low or too high.
* Poor aircraft spray patterns.
The variables which cause these two problems defy quantification in
the strict sense. However, these problems are important enough to warrant
concern. Overapplication and nonuniform distribution are both current and
future problems that must be dealt with if the efficiency of pesticide
applications in agriculture is to be enhanced.
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Loss Potential During Application
Pesticides are lost into the environment at the time of application
when they drift away from the crop being treated and impact away from the
target area. Under certain circumstances, these losses are substantial
and may pose both an immediate and long-term hazard to the surrounding
environment. Drift is neither accidental nor entirely uncontrollable, and
its occurrence reduces the efficiency of agricultural pesticide applica-
tions.
Drift is a rather complex physical event which is influenced by a
variety of interrelated factors,, The potential for the occurrence of spray
or solid particle drift depends primarily upon meteorological conditions,
properties of the particle itself, and operational application techniques.
Important factors affecting drift are wind speed and turbulence; particle
size and density; evaporation rate of the liquid; spray nozzles and dis-
charge pressures; distance between application equipment and target; and
volumes of pesticide formulations applied.
This study took all of these factors into account and estimated the
likelihood of drift for various types of equipment and application tech-
niques commonly used in agriculture, paying particular attention to field
crops and orchards. The estimations developed in this study are given in
Table 1. The biggest drift hazards occur as a result of using dusts and
aerial spraying.
In addition to examining drift losses in agricultural chemical crop-
treating operations in general, the estimates developed in the study were
applied to the three study crops. Between some hard facts and some assump-
tions in cases where information was unavailable, the losses due to pes-
ticide drift during application were estimated for the applications made
to the UoS. corn, sorghum, and apple crops in 1971, the most recent year
for which pesticide use statistics on these crops are available. The esti-
mates for pesticide drift loss are included in Table 2, both as percent-
ages and as quantities of active ingredient used that year.
Herbicide losses were low on a percentage basis, but the quantities
lost were the largest for the four groups of pesticides. Insecticide
losses were the highest in the apple orchards primarily due to the use
of dusts and orchard airblasters. Sorghum losses were greater than those
of corn since most insecticides used on sorghum are applied by air,
whereas corn insecticides are applied to the soil, mostly preemergence.
Fungicides and other pesticides are not used on corn and sorghum to any
significant extent, while fungicides are used extensively on apples.
Again, drift losses were high in the apple orchards for fungicides since
some are applied as dusts, and about half as sprays from airblasters.
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Table 1. LIKELIHOOD OF PESTICIDE DRIFT DURING CROP TREATMENT IN AGRICULTURE
BY METHOD OF APPLICATION
Formulation Equipment type
Dust Aircraft, venturi
Airblaster
Spray Tractor, boom
sprayer
Tractor, boomless
sprayer
Spray gun
Orchard airblaster
Aircraft, boom
sprayer
Granular Aircraft, venturi
Spreader, centri-
fugal
Spreader, boom
Planter
Pesticide
application method^'
Air, foliar
Ground, foliar
Ground, foliar
Ground, foliar
Ground, broadcast
Ground, broadcast
Ground , band
Ground, band
Ground, broadcast
Ground, broadcast
Ground, foliar
Ground, foliar
Ground, foliar
Air, foliar
Air, foliar
Air, foliar
Air, foliar
Air, broadcast
Air, broadcast
Ground, broadcast
Ground, broadcast
Ground, band
Ground, band
Target
Trees
Trees
Plants
Plants
Soil
Soil
Soil
Soil
Soil
Soil
Trees
Trees
Trees
Trees
Trees
Plants
Plants
Soil
Soil
Soil
Soil
Soil
Soil
Spray
application volume^'
_
-
ULV
LV
LV
HV
ULV
LV
LV
HV
HV
ULV
LV
ULV
LV
ULV
LV
LV
_
-
'
-
—
Estimated percent
drift over 1,000 ft
from target^.'
70-90
60-80
5-10
1
Negligible
Negligible
Negligible
Negligible
Negligible
Negligible
3-5
40-70
10-40
40-60
10-40
40-60
10-40
10-40
1-2 .
1
1
Negligible
Negligible
aj Air refers to pesticide application by aircraft, ground refers to pesticide application by ground rigs.
b/ HV = High Volume; LV = Low Volume; ULV = Ultra-Low Volume.
c/ Assumes a 3 to 5 mph wind; neutral atmospheric stability (S.R. = 0), air temperatures above 60°F; and
a relative humidity of 50% or less.
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00
Table 2. ESTIMATED LOSSES DURING AND AFTER APPLICATION OF
PESTICIDES TO CORN, SORGHUM AND APPLES (1971)
Pesticide and
loss route
Herbicides
Drift
Runoff
Total
Insecticides
Drift
Runoff
Total
Fungicides
Drift
Runoff
Total
Other pesticides
Drift
Runoff
Total
Corn
% loss^7 Lb lost (000)
0.8-3.0 800-3,000
0.5-3.2 500-3,200
1.3-6.2 1,300-6,200
0.2-0.7 50- 180
0.3-1.3 80- 330
0.5-2.0 130- 510
Negligible
Negligible
Negligible
Negligible
Negligible
Negligible
Sorghum
% loss-/ Lb lost (000)
1.0-3.9 120-450
0.6-3.4 70-390
1.6-7.3 190-840
6-25 360-1,400
Negligible
6-25 360-1,400
Negligible
Negligible
Negligible
Negligible
Negligible
Negligible
Apples
% loss-' Lb lost (000)
Negligible
Negligible
Negligible
21-42 1,000-2,000
Negligible
21-42 1,000-2,000
21-42 1,500-3,000
Negligible
21-42 1,500-3,000
Negligible
Negligible
Negligible
&j Percent loss refers to the percentage of the amount applied.
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PESTICIDE LOSSES AFTER APPLICATION AND BY MISCELLANEOUS DISCHARGE
Pesticide losses that occur after application are the result of pes-
ticide transport away from the crop by the natural forces of runoff and
soil erosion. Losses which occur through miscellaneous discharges are the
result of spills and disposal techniques. Each of these pesticide loss
routes are discussed below.
Loss Potential After Application
Pesticide quantities deposited in the target area may impact on the
target crop, on the ground, or on other nontarget surfaces in the target
area. A portion of the deposit on the crop may be washed off and impact
on the ground secondarily at various times after application.
The principal mechanisms of pesticide transport away from treated
fields after application are: (a) surface runoff including both sediment
and water; (b) volatilization; and (c) leaching to ground water. The mag-
nitude of the losses varies with each pesticide and environmental condi-
tions. Generally, surface runoff and volatilization are the dominant mech-
anisms for pesticide loss from cropland. Degradation by chemical, physical
or biological processes is not a transport or "avoidable loss" mechanism
within the definitions established for this study and was therefore not
included in its scope. Volatilization is a process which is beyond the
control of the farmer once the pesticide has been properly applied (and
soil incorporated, if required). Since this study deals with avoidable
losses of pesticides, only surface runoff was studied in detail.
The primary objective in examining the incidence of runoff was to
quantify the pesticide losses involved. After defining the variables that
affect the amount of runoff that occurs with rainfall and soil management
practices in agriculture, two methods were used to try to estimate the
quantities of pesticides lost in runoff from the study crops. The first
method involved estimating the amount of runoff occurring on the crops,
and the concentrations of pesticides involved. The second method consisted
of estimating the total pesticide loss as a percentage of the amount ap-
plied, and relating this to the amounts applied to the study crops in 1971,
The first method proved unsatisfactory. Statistics were developed
for runoff losses only since soil losses cannot be reasonably estimated
for a large crop due to the complexity of the many variables involved.
Both annual runoff maps and rainfall maps were used to estimate the run-
off from the corn and sorghum crops (apples were not included since soil-
applied pesticides are used in small quantities in orchards). Concentra-
tions of herbicides and insecticides in runoff water were determined from
field studies reported in the literature. However, quantification of the
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pesticide losses on the two crops was not undertaken by this method since
the variables involved required too many assumptions. There is no current
method of accurately determining the amount of runoff from crops, and the
work done in this study helps to show why.
The second method was used to quantify the herbicide losses from the
corn and sorghum crops in 1971 and the quantities determined are shown in
Table 2. The percentages of pesticides lost as a percent of the amount
applied were determined from field studies reported in the literature.
These percentages were then used with the amounts of herbicides actually
applied to corn and sorghum in 1971 to determine the loss.
Table 2 shows that herbicide losses from corn and sorghum crops
amounted to 3% or less of the amount actually applied to the soil. How-
ever, this amounts to as much as 3 million pounds of active ingredient,
a substantial quantity.
Miscellaneous Pesticide Discharges
Pesticide losses due to spills and improper disposal were not evalu-
ated in detail in this study. Losses from these two mechanisms reduce the
overall efficiency of agricultural pesticide use. However, spills are pri-
marily accidents and disposal techniques are within the control of man.
Pesticide accidents as well as losses due to improper disposal of pesti-
cides or containers can be reduced or avoided by improved operator train-
ing, performance and supervision.
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SECTION III
PESTICIDE WASTES AND LOSSES OCCURRING DURING APPLICATION
INTRODUCTION
Pesticides are applied to corn, sorghum, and apples to control a
wide variety of pests. The use of these pesticides is usually economically
advantageous in the production of these crops, but at the same time pes-
ticides can produce undesirable results when inefficiently applied or in-
advertently lost to the environment. The ultimate objective of chemical
pesticide application is to control unwanted pests in as efficient a man-
ner as possible.
There are several potential sources of waste involved in the appli-
cation of pesticides, and this section examines three of the more impor-
tant ones--overapplication, nonuniform distribution, and drift. Each sub-
ject is discussed with two objectives in mind. One is to identify the
factors which cause pesticides to be wasted, and the other is to quantify
the wastes to the extent possible. Therefore, both a qualitative and a
quantitative treatment is given to each subject as it is examined and
discussed.
The three subjects involve both pesticide overuse and application
losses. Overuse is pesticide overapplication and nonuniform distribution
during crop treatment resulting from problems associated with the physi-
cal characteristics and operation of the application equipment. Applica-
tion losses involve the drift of chemicals away from the crop at the time
the pesticide is applied.
Since the three topics discussed in this section involve pesticide
wastes and losses that occur during application, the first section that
follows describes the typical pesticide applications that are used in
agriculture. The second section discusses problems of overapplication and
nonuniform distribution, and the third section discusses pesticide drift.
11
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TYPICAL PESTICIDE APPLICATIONS USED IN AGRICULTURE
An understanding of the pesticide wastes and losses that occur dur-
ing application requires a working knowledge of the kinds of pesticide
applications that are used in agriculture. The most common applications
encountered in crop treatment can be conveniently divided into three cat-
egories: (a) dust applications; (b) granular applications; and (c) spray
applications. Each of these categories are discussed separately below to
present the typical formulations, methods of application, and uses of
each type of application.
(a) Dust applications - The practice of dusting crops with pesti-
cides has diminished greatly since the 1940's. Over 60% of the aerial
applications of pesticides at that time were dust formulations, but by
1963 the percentage had dropped to an estimated 20%..i' Even less dusting
is done today since the problems of drift and low deposit efficiencies
of dust particles still remain. There are situations, however, where
dust applications are advantageous for good coverage of the crop. Special
coverage problems such as dense foliage, vines, and orchards with sig-
nificant crop depth cannot be penetrated easily by sprays, so dusts are
used.
Formulations consist of finely divided solid particles of pesticide
that are used in concentrate form or mixed with an inert carrier. Some of
the more common carriers are organic flours, lime, talc, gypsum, silicon
oxides, bentonites, kaolins, sulfur, volcanic ash, and attapulgite. The
concentration of active ingredient in dust formulations is usually low
(0.1 to 20%), and most formulations are applied to the crop directly with-
out further dilution.
Particle size of dusts is between 1 and 50 p,. Sizing is conducted by
the manufacturers of dusts using a screening operation, and commercial
dusts normally range between 30 and 50 p,, while dust concentrates are sized
between 1 and 30 p,, with a stated average of 80 to 90% of the formulation
below 25 p,.
The method of application used in agriculture employs an airblast
technique to blow the dust onto the plants from ground rigs, or employs
the use of aircraft to dispense the dusts over the plants. Field crop
dusters (rarely used any more) apply dusts directly over plants from
booms attached to a blower. Orchard dusters blow the dust up into the
trees from automatic nozzles or hand-held guns. Aircraft, both fixed
wing and rotary wing, dispense the dust over the crop from venturi de-
vices.
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(b) Granular applications - Many of the agricultural herbicides and
insecticides are formulated as granules, and the market for granules has
risen rapidly in recent years. Granules are used as both preemergent and
postemergent herbicides, soil- incorporated insecticides and preemergent
fungicides. The market for these products now exceeds 100,000 tons/year.—'
Formulations consist of inert carriers impregnated with the pesti-
cide. The most common carriers used, in the order of their importance,
are: attapulgite, montmorillonite, bentonite clays, granular diatomace-
ous earths, and vermiculite (almost exclusively used in the home and gar-
den market). Concentration of pesticides in granules range from 2 to 40%
active ingredient — the most common concentrations in agricultural pesti-
cides being 5 to 20%. Specific gravities of the products range from 2,0
to 3.0 with the typical formulation having a specific gravity of about
Particle size of granules is determined by screening the product
after manufacture. Granular products are defined as solids with a parti-
cle size between 4 and 80 mesh, U.S. standard sieve size (less than 80
mesh are considered dusts). Granule size is specified for a particular
product by labeling it 8/16, 18/35, 20/40, 30/60, etc. This designation
means that the product has been screened so that most of the particles
are retained on the second screen (large number) after passing through
the first screen (small number). The NACA Granular Pesticide Committee
has recommended that at least 90% of the product should lie between the
two designated screen sizes..?.'
The most common sizes used in agriculture are medium and fine. Soil
incorporated insecticides are predominantly the medium sized granules,
18/35 and 20/40; and herbicides and insecticides applied above the soil
are usually the finer sizes, 25/50 and 30/60 mesh. The tabulation!/ below
shows the U.S. standard sieve series number and the corresponding screen
size opening in microns s
U0S« standard sieve number Screen opening (microns)
35 500
40 420
50 297
60 250
80 177
This tabulation shows that most agricultural granular pesticides have a
particle size above 250 p, (60 mesh).
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The method of application used in agriculture takes three forms:
(a) broadcasting the granules on the soil surface; (b) broadcasting and
incorporating the granules into the soil; and (c) applying the granules
in bands (rows) either on or below the soil surface. Broadcasting of
granules is achieved with either ground or aerial equipment. Ground equip-
ment is normally a tractor-drawn boom that dispenses the granules from
nozzles, or a tractor-drawn (or mounted) centrifugal broadcaster. Aerial
equipment is normally a fixed-wing aircraft that dispenses the granules
from venturi or centrifugal spinning-disc spreaders. Broadcasting and in-
corporating the granules into the soil can be done by ground equipment
dispensing the granules onto the soil ahead of reels or rotary hoe units.
Soil incorporation can be a separate operation following the broadcast-
ing of the granules by ground or aerial equipment. Any implement that
tills the soil (such as rotary tillers and discs) can be used. Band ap-
plications are normally done at the time of planting by dispensing the
granules from fan shaped nozzles attached to hoppers mounted on the
planter. The granules can be applied ahead of the planter (preplant) and
soil incorporated, or behind the planter (preemergent) on the soil sur-
face.
The application equipment operation varies depending upon the method
of application. The operating parameters which are typical in agricul-
tural pesticide application of granules are summarized below:
. Aircraft - fly at 90 to 120 mph, release granules at a height of
9 to 12 ft (12 typical).!/
• Ground broadcasters - release granules at a height of about 3 ft,
both centrifugal and drop-type booms.
. Ground band applications - release granules at a height of about
6 in. or drill into the soil.
(c) Spray applications - The vast majority of herbicides and many
of the mijticides, insecticides, and fungicides are applied to the crops
and crop soil by spray applications. The unique advantage spraying has
over granules is that the pesticide can be readily applied to the plants
themselves, whereas granules are less adaptive to this use. The signifi-
cance of spray applications in agriculture was aptly summarized in a re-
port by G. W, Ware2/ when he quoted the statement "almost all pesticide
applications, particularly herbicides, are in the form of sprays, usually
water emulsions and wettable powders" (USDA, 1967).
Spray applications vary widely in formulations, methods of applica-
tion, and application equipment used. To discuss these many variables it
is most convenient to separate the spray operations into ground and aer-
ial equipment applications. These two sectors can then be subdivided as
required to cover the many facets of operation involved in each sector.
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The following discussion addresses ground equipment and aerial equipment
separately.
(1) Ground equipment - Sprays applied with ground equipment have
two primary targets: (a) the crop soil; and (b) the crop plants. Some
vector control is employed in agriculture, but it is a relatively small
aspect of pesticide use and will receive no consideration in this study.
The spraying of crop soil is conducted primarily to apply herbicides for
weed control and the spraying of the crop plants is conducted to apply in-
secticides, miticides, and fungicides to control pests attacking the crop
plants.
The types of equipment used for the application of sprays to the
soil and to plants growing a short height above the ground (primarily field
crops) differs from that for application of sprays to tall plants (mostly
trees). Since the application equipment, and, therefore, the technique used
is different in each case, the subjects are discussed separately.
Field crops - Field crops are treated nearly exclusively with
sprays in applying herbicides to the soil, both preemergent and postemer-
gent, and with sprays in applying insecticides to the plants. Some use of
granules and even less of dusts is still practiced in foliar applications
but these uses are small in relation to the total quantities of pesticides
foliarly applied. Soil application of granular herbicides is small relative
to spray formulations, but the use of granular insecticides is still widely
practiced. Spray applications of herbicides and insecticides to the soil
and foliar applications of insecticides to plants are the topics of discus-
sion in this section.
Formulations consist primarily of wettable powders suspended in
water, and water emulsions. Wettable powders are mixtures of active ingredi-
ents, inert carriers, surfactants, and adjuvants that can be suspended in
water for application. These powders generally contain a high concentration
of active ingredient (15 to 957o), and individual particles are normally
sized in the same size range as dusts (less than 50 p,), with recommendations
that no more than 2% of the powder material should exceed 200 mesh (74 u.).—'
Water emulsions are formed with emulsifiable concentrates (EC), formulations
that are solutions of active ingredient and emulsifiers in a solvent. The
emulsifiable concentrate is diluted with water before application. Concen-
trations are typically 15 to 50% for a single active ingredient and as high
as 80% for formulations containing an active ingredient mixture.
The method of application used in field crops takes three basic
forms: (a) broadcasting the spray on the soil; (b) banding the spray on the
soil; and (c) applying the spray directly to the plants. Broadcast applica-
tions are sprayed from nozzles mounted along a boom or mounted on the spray
15
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tank. Booms are tractor-drawn or tractor-mounted and fed from the spray
tank. Boomless operations are simply nozzles attached to the sides or back
of the spray tank. Band applications are sprayed from nozzles on booms
similar to broadcast applications, but cover only a 7 to 14 in. band (row)
on the soil. Distances between the bands depend upon the row spacing for
the field crop. Foliar applications are the same as band operations, ex-
cept they apply the spray to the plants instead of the soil. In tall row
crops the booms and tractor used to transport the spray nozzles above the
plants are high-clearance, self-propelled units, since tractors cannot
operate in the field when the plants are present (such as corn).
The nozzles normally used with each type of operation are:
Soil, broadcast - fan spray and flooding nozzles (boom) and
flat spray (boomless).
. Soil, band - fan spray nozzles.
Foliar - cone and disc-type cone nozzles.
The volume of spray* per acre is generally classified as ultra
low volume, low volume, or high volume. Ultra low volume (ULV) is less
than 10 gal/acre for soil broadcast, soil band, and foliar applications.
Low volume (LV) is 10 to 40 gal/acre for all three operations, and high
volume is greater than 40 gal/acre for all three operations (sometimes
hundreds of gallons per acre when saturating the foliage with spray solu- .
tion).
Height of application above the target (soil or plants) varies
with each type of application. Soil broadcast operations using booms nor-
mally operate at a height of about 12 in. above the soil using flooding
nozzles, and from 16 to 24 in. above the soil using fan spray nozzles.
Fan spray nozzles are by far the most common in use on booms and are typi-
cally operated 18 in. above the ground with about a 50% overlap spray pat-
tern for uniform coverage (fan spray nozzles used in broadcast applications
deliver a higher rate of spray in the center of the pattern than at the
periphery). Boomless operations normally use flat spray nozzles located
3 ft above the ground. Band applications to the soil primarily employ wide-
angle (80, 95, and 110 degrees) fan spray nozzles that distribute the spray
The terms ultra low volume, low volume, and high volume are relative
terms which are not precisely defined, and the volume per acre assoc-
iated with each terra varies for different types of operations. The
volumes of spray per acre associated with ULV, LV, and HV are defined
for each type of operation in this report, and are the volumes gen-
erally, though not universally, accepted in practice.
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evenly across the band width, and are operated 4 to 8 in. above the soil
at an average height of 6 in. Foliar applications to field crop plants
primarily use cone or disc-type cone nozzles in several various arrange-
ments to spray the plants. Different nozzle arrangements include a single
nozzle placed vertically over the plant; two nozzles over the plant at
an angle from the vertical; and a three-nozzle arrangement with one noz-
zle vertically above the plant and the other two nozzles to the side of
the plant. The height of the nozzles above the plant are typically 12 in.
and the height of the nozzles above the ground, of course, depend on the
plant height itself (plus about 12 in.).
The next section discusses the technique of ground application
in orchards.
Orchards - Orchards are treated with herbicides, insecticides,
fungicides, and miticides. Herbicide treatment of the orchard soil is
conducted by ground spray application equipment exclusively since the
herbicides commonly used cannot contact the trees without severly damag-
ing them. Insecticides, miticides, and fungicides are sprayed on the trees
from airblast machines and spray guns in ground operations.
Formulations consist primarily of wettable powders and emulsi-
fiable concentrates. Herbicides are normally water diluted to provide
at least 10 gal/acre of liquid so that application pressures can be main-
tained low to reduce the drift hazard. Concentrations of insecticides,
fungicides, and miticides are normally expressed as IX, 2X, 3X,* etc.
This refers to the amount of water dilution of the concentrate or wet-
table powder used. The terms refer to dilute (IX) to concentrated (6X
or higher) and the volume of water used varies from 400 to 600 gal/acre
for IX concentrations down to about 50 gal/acre for 6X.—' Some ultra
low volume operations use even less volume, down to the amount of con-
centrate itself in the case of emulsifiable concentrates.
The method of application used in orchards takes three basic
forms: (a) broadcast or spot-treatment of the soil with herbicides; (b)
spraying the trees with a high-pressure, high-volume spray technique;
and (c) spraying the trees with an airblast technique. Herbicide treat-
ment of the soil is accomplished with tractor-drawn booms for broadcast
treatment and backpack sprayers for spot treatment. The booms are oper-
ated at low pressures, and high volumes (dilute) of herbicide are used
to avoid damaging drift. High-volume, high-pressure applications of
foliar pesticides are achieved by wetting the trees to the runoff point
The term IX refers to the normal amount of water used in dilute spray-
ing which has been determined through research and experience over
the years. The term 2X means one-half the normal amount of water,
3X is one-third, etc.-/
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to afford adequate coverage and uniform distribution. Automatic or hand-
held spray guns are used, and the spray tank is normally mounted on a
truck since the volume of water required is normally 400 to 600 gal/acre.
Airblast sprayers, developed in the 1940's, have largely replaced high
volume spraying and are either tractor-drawn or truck-mounted units con-
sisting of a spray tank, large blower, and peripheral nozzle arrange-
ments. These sprayers operate on the principle of using air as the trans-
port medium for the pesticide, and function by blowing air laden with
pesticide through the trees in large enough quantities to displace the
existing air surrounding the tree. The pesticide may be applied in dilute
or concentrated formulations.
The volume of application per acre is classified as high volume
(more than 50 gal/acre), low volume (about 10 to 50 gal/acre) and ultra
low volume (less than 10 gal/acre). High-volume applications are not com-
monly used today since handling and transporting large volumes of water
is time-consuming and expensive. Most orchard spraying is done with low
volumes, and some with ultra low volumes.
(2) Aerial equipment - Aerial application of pesticide sprays
to treat crops has increased over the past few years. In 1973, statistics
kept by the FAA show that 1,869,000 hr were flown by aerial applicators
in the United States. The national average figure for acres of crops
treated per hour is 80. These statistics show that about 150 million
acres of crops were treated by aerial applicators in 1973, The estimate
for 1974 is an approximate increase of 20% over the 1973 figure, or about
180 million acres.!/
About 90% of the spray formulations aerially applied to crops
are applied in low volumes of 1 to 10 gal/acre.2/ Most of the applica-
tions are in the 3 to 5 gal. range. Of the remaining 10%, about half is
applied in ULV of 1 gal. or less per acre and the other half at about 20
gal/acre. Since the major pesticides used are applied at the rate of 1
to 2 pt of pesticide solution per acre (undiluted basis) and are formu-
lated to contain 4 Ib of active ingredient per gallon, the total amount
of active ingredient aerially applied was between 75 and 150 million
pounds in 1973.
Sprays applied by aircraft have two primary targets: (a) the
crop soil; or (b) the crop plants. Most aerial pesticide applications
involve spraying the crop plants with insecticides, fungicides, and
miticides. Some soil applications are performed but these are in a mi-
nority, since most herbicides are applied as sprays by ground equipment
and soil insecticides are commonly applied as granules.
18
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The formulations used in aerial spraying do not differ markedly
from those of ground applicators. Wettable powders and eraulsifiable con-
centrates are commonly used with aircraft also.
The method of application takes the form of a broadcast spray
over the entire crop, whether treating the plants or the soil. Aircraft,
both fixed wing and rotary, have components similar to ground rigs, and
continuous spray booms with nozzles spaced about 1 ft apart are mounted
below the aircraft to spray the pesticide.
The nozzles normally used with aircraft are hollow cone, but
fan spray and jet nozzles are sometimes used to produce coarser droplets.
The volume of spray per acre is either low volume or ultra low
volume. Low volume is considered to be 1 to 10 gal/acre, with the typi-
cal application rate between 3 and 5 gal/acre. Ultra low volume amounts
to spraying the undiluted pesticide concentrate at rates below 1 gal.s
usually from 1 to 2 pt/acre.
The height of application varies for different types of opera-
tions. Applications to the soil are normally applied at heights of 5 to
10 ft over the ground; field crop plants are sprayed at heights of between
10 and 15 ft; and orchards are sprayed at heights just above the trees
and vary according to tree heights.
PESTICIDE OVERAPPLICATION AND NONUNIFORM DISTRIBUTION
Overapplication means the dispensing of pesticides to the entire
crop at an unintentionally high rate of application, or in heavy doses
in a spotty, nonuniform manner. This overuse of chemicals occurs pri-
marily because of equipment problems—either physical or operational.
The efficiency with which pesticides are applied to the three study
crops depends heavily upon proper use of the application equipment,, This
equipment invariably has design features or operating characteristics
that must receive careful consideration in order to achieve maximum ef-
ficiency. Research on application equipment has been concerned for years
with improvement in the uniformity of distribution of pesticides, because
the required rate of application for many pesticides could be reduced
without loss of effective pest control if uniformity of distribution
could be attained. Conversely, when pesticides are applied in a spotty
or inconsistent manner, more chemicals may be needed in order to achieve
the desired results. To the degree that nonuniform application adds to
the total amount of pesticide used to achieve effective control, it is
a form of overapplication.
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Overapplication in a more direct sense involves applying pesticides
at a rate higher than that intended. This can be caused by both faulty
equipment characteristics and erroneous operation of the equipment. When
pesticides are overapplied, regardless of the reason, their use must be
considered wasteful and unnecessary.
The discussion of overapplication and nonuniform distribution is di-
vided into two sections. The first section considers the physical features
of the application equipment which most affect efficient pesticide appli-
cation. The second section considers the human element in the operation
of equipment and its effects on application efficiency. Each section is
followed by a brief statement on the quantification of overapplication
and nonuniform distribution.
Physical Equipment Problems
Since the vast majority of pesticides applied to crops are either
sprayed or granularly applied, the following discussion is confined to
spray equipment and granule application equipment. The equipment features
examined in this section affecting the rate and uniformity of application
are: (a) metering devices; (b) nozzles; and (c) spray tank agitation.
Metering Devices - Granule applicators all employ some type of metering
device to control the rate of application. These devices are primarily
responsible for the uniformity of the rate of application. As an example
of the problems that can develop with metering devices, consider the drop-
type applicator. The most common metering device used on drop-type units
is a ground-driven vaned or fluted horizontal rotor-bar agitator between
the hopper and an adjustable discharge opening. Other devices include var-
iable orifices with a rubber-flanged impeller; a fixed orifice with a var-
iable screw-conveyor auger; and a variable orifice between the hopper and
an oscillating plate.
Once the discharge openings have been set (whether adjustable or
fixed), the discharge rate is dependent on, among other things, the speed
of the horizontal vaned or fluted rotor that dispenses the granules. Under
ideal conditions, the discharge rate is proportional to the rotor speed
so that the application rate is unaffected by forward speed of the unit.
Unfortunately, this is not usually the case, and as the applicator (which
is normally tractor-mounted or tractor-drawn) is used to treat the crop,
the speed at which it moves varies. This variation in application speed
causes variations in the amount of granules dispensed, and therefore,
nonuniform distribution.
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The effect speed has on the discharge rate depends on a number of
variables including the type of rotor and the size of the granules. Vaned
rotors should operate at 7 to 20 rpm, while fluted rotors sometimes oper-
ate slightly faster than 20 rpm,, If the speed is too low, erratic flow
results; if the speed is too high, the granules may be excessively ground.
To point out the complexity of this problem, the following excerpt is
taken from Principles of Farm Machinery;^./ "Some tests with vane-type
rotors have shown decreases in discharge rate as the rotor speed is in-
creased. Other tests with the same types of rotors have shown a moderate
increase (but never proportional to speed). In tests with different gran-
ule sizes, the rate tended to increase with speed for large granules and
to decrease with increased speed when the granules were small. When a
rubber, fluted roll ... was tested, the discharge rate was found to be
nearly proportional to speed between 5 and 15 rpm, but there was no change
between 25 and 50 rpm."
In addition to variable discharge rates occurring with variable
speeds and granule sizes, cyclic rate variations corresponding to the fre-
quency of the vanes passing the discharge opening have been observed. This
means that as the applicator moves forward, the amount of granules depos-
ited will vary from small amounts to larger amounts in a cyclic fashion
as the rotor revolves and dispenses the pesticide. For example, a six-
vane rotor turning at 12.5 rpm and a forward speed of 3 mph, has a cycle
whose length is 42 in. along the row. The cyclic variation of the amount
of granules deposited on the soil can be significant, and various investi-
gations of this phenomena have shown that the ratios between maximum and
minimum cyclic rates for 3- to 5-in. increments ranged from 2:1 to 5:L2/
(meaning that two to five times as much pesticide is deposited in heavy
dosage areas compared to light dosage areas). Fluted rotors should have
smaller cyclic variations than the vane-type rotors since the displace-
ment per flute is smaller than the displacement per vane (vanes protrude
a greater distance from the rotor than do flutes). Cyclic variations will
also become more severe as the discharge opening is increased, and will
increase if impacts are experienced (especially on rough terrain) when
operating the applicator.
The nonuniformity of granular pesticide application experienced from
cyclic variations and variable rotor speeds is a problem existing in ag-
riculture today. Operating the applicator (normally pulling it behind a
tractor) at different speeds when treating the field can cause nonuniform
distribution. Generally, lower application will occur when speed is in-
creased, depending upon the variables discussed above. Even if a constant
speed were maintained throughout the treatment, the cyclic variations
caused by the revolution of the rotor would cause distortions in the ap-
plication rate. Since from two to five times the minimum dosage rate oc-
curs in the maximum dosage areas, these heavy dosage areas can be consid-
ered nonuniform overapplications of the pesticide. If pesticide migration
21
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is minimal or the concentration of pesticide in the soil is proportional
to the rate applied at any given point, the low dosage rates effect con-
trol of the field pest in the areas in which they occur, and the heavy
dosage areas receive a wasteful overapplication.
Nozzles - Spray nozzles form the discharge openings in most spray appli-
cators. They are used to direct the flow of liquid, and, in conjunction
with the discharge pressure, to control the rate of application and size
of the particles sprayed. Nozzles vary according to type, orifice size,
and materials of construction. Each of these variables is important in
determining the effectiveness and efficiency of the spray application.
There is a wealth of literature on the research that has been done
toward the optimization of nozzles to obtain efficient application and
uniform distribution of sprays. A brief treatment of the subject will be
considered in this section as it applies specifically to the application
problems experienced in agriculture.
When nozzles are improperly used, nonuniform distribution and/or
overapplication of the pesticide may occur. The basic problems consid-
ered here are: (a) improper atomization; (b) clogging; and (c) nozzle
wear.
Improper atomization occurs when droplets are formed either too
large or too small. If they are too large, coverage is often spotty and
nonuniform; if too small, particle drift increases, and deposition on
the target surface is less likely. Even if the proper nozzles for good
atomization are mounted on a boom-type applicator, problems can still
occur. The rate of application in gallons per acre is a function of the
spacing of the nozzles on the boom, nozzle orifice size, nozzle pressure,
and rate of forward travel. This relationship takes the general form of:
/ \ (GPM per nozzle) (Constant)
(Gallons per acre) = j—;—fr -4—•* ; ~t—— .
Speed (mph) x nozzle spacing (in.)
The equipment owner normally buys nozzles based on the manufacturer's
and seller's recommendations for his particular needs. With a given num-
ber of nozzles and the fixed spacing on the boom, the nozzles used will
be of a certain orifice size and pressure requirement. However, the oper-
ator may decide he wishes to drive faster or (rarely) slower than the
speed for which application is calibrated, or to change the concentration
of pesticide to be applied. (This occurs most often if the operator uses
more than one pesticide or different ones the following year.)
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From the above formula it can be seen that driving at higher speeds
or using different concentrations causes the rate of application to vary
unless the discharge rate from the nozzles is changed proportionately.
For faster application speeds, the nozzle output must increase for a
given application rate, and for higher application rates, the nozzle out-
put must increase also. To increase the output, two basic adjustments can
be made: (a) use large orifice nozzles; or (b) increase the discharge
pressure. The tendency to increase pressure is great, particularly if the
rate of application is close to the desired one. (This sometimes occurs
with the initial purchase of nozzles since they do not always produce the
desired effects due to variables in the equipment operation.) However,
increasing the pressure produces smaller particles that tend to drift
more, and coverage may be inadequate. Decreasing pressure produces the
opposite effect in that droplets produced are larger and coverage is
often spotty. The main point is that if the rate of application is not
the proper one at the time of calibration, a change in operating speed
or a change in nozzles should be made rather than a change in the pres-
sure unless the adjustment is a very minor one.
Clogging occurs when nozzles are improperly maintained and is more
prevalent with small orifice nozzles. To avoid clogging, frequent clean-
ing (sometimes daily) should be performed by flushing the nozzles. To
remove an obstruction that is plugging the nozzle, a wood splinter can
be used. Nails or wires should never be used since they may scratch the
precision surfaces and distort the spray pattern. If frequent clogging
occurs during operation, nozzles with larger orifices are needed. When
clogging does occur, the uniformity of application is, of course, ad-
versely affected.
Nozzle wear has become an increasing problem primarily due to the
increased use of abrasive wettable powder formulations. The output of
solution increases as nozzles wear and Figure l2/ shows how flow will
increase due to nozzle wear when spraying a typical wettable powder form-
ulation. This figure shows that brass nozzles wear rapidly and that ap-
plication rates will increase as the pesticide is applied, resulting in
overapplication. Even with the chrome-plated brass nozzles some over-
application will occur if wear during the period of application is not
taken into consideration. The use of brass-bodied nozzles with hardened
stainless steel cores and orifices are probably the most satisfactory
combination. All nozzles, however, must be periodically recalibrated or
replaced to insure that pesticides are applied at the desired rate.
Another type of nozzle that needs consideration is used on the hop-
pers of granular applicators when applying granules in bands or rows.
Though these devices are sometimes called spreaders or diffusers, they
23
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STAINLESS STEEL
r-CHROME-PLATED BRASS
3 6 9 12 15 18
TIME (Mrs)
Figure 1. Flow increase due to nozzle wear, when spraying
a typical wettable powder formulation.
Source: Beasley, E. D., and Glover, J. W., "Orchard Spray
Equipment," North Carolina Agricultural Extension
Service, Circular 501, January 1969.
24
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are a type of nozzle used extensively in agriculture to dispense gran-
ules in band applications. The most common type used with granular appli-
cators are fan shaped. Dispersion is obtained by baffle plates, splash
pins, or perforated dividers within the fan. These nozzles are mounted
over the discharge openings of the applicator to control the lateral di-
rection of the granular pesticide flow.
Bands are typically 7 to 14 in. wide, and may be formed with a sin-
gle fan or two fans fed from separate hopper discharge openings. The uni-
formity of distribution in a lateral direction is not much better than
the uniformity of distribution in a forward direction. Experimental tests
have shown that irregular lateral distribution patterns are formed, with
the ratio of maximum to minimum discharge rates for 1-in. increments of
width ranging from 2:1 to 5:1 (similar to the forward direction cyclic
variations).^./ As a result of these irregularities, the problem of non-
uniform distribution is enlarged when the lateral variations are super-
imposed upon the down-the-row variations, causing similar but magnified
distortions in band applications compared to broadcast applications of
granular products. The problems of nonuniform distribution and overappli-
cation due to these effects that were discussed in the previous section
apply to this situation as well.
Spray Tank Agitation - Liquid reservoir tanks used in spray application
equipment are agitated mechanically or hydraulically. Mechnical agitation
is normally done with a series of paddles on a shaft that runs horizon-
tally through the tank or by a propeller at one end of the tank. Hy-
draulic agitation is accomplished by routing a portion of the pressuri-
zed spray liquid back into the bottom of the spray tank through a series
of jet nozzles or orifices. Mechanical agitation is normally used for
oil emulsions and wettable powders, whereas hydraulic agitation is com-
monly used for soluble or self-emulsifying solutions.
Agitation is necessary to keep the spray ingredients uniformly mixed,
particularly in the case of wettable powders and oil emulsions, since
these formulations may separate from water if allowed to stand. If sep-
aration does occur, the uniformity of application is adversely affected.
Figure 22.' shows how the application rate of a wettable powder is affected
without agitation: the rate falls drastically with time as the solution
separates. Therefore, it is important that such liquids be agitated dur-
ing spraying. If the tank has no agitation system, an agitation system
inadequate for the liquid being mixed, or an inoperable agitation system,
then the uniformity of the pesticide distribution will be adversely af-
fected. The operator may apply the proper volume of spray to his crop,
but the amount of pesticide in the spray mixture applied without proper
agitation will vary greatly with time.
25
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100
90
^ 80
£ 70
* 60
| 50
to 40
uj
0 30
20
i
i
i
369 12 15
TIME-MINUTES
Figure 2. Decrease in application rate of a wettable powder with time,
sprayed from a tank with no agitation.
Source: Beasley, E. D., and Glover, J. W., "Orchard Spray Equipment,"
North Carolina Agricultural Extension Service, Circular 501,
January 1969.
26
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Operational Equipment Problems
The operation of the application equipment must be done properly to
minimize nonuniform distribution and ovcrapplication of the pesticide.
Several factors critical to satisfactory application of the pesticide
are: (a) equipment calibration; (b) proper forward speed of the unit;
(c) proper height of the spray boom; (d) proper pesticide formulation;
and (e) proper aircraft spray distribution. Each of these criteria of
operation is discussed separately below.
Equipment Calibration - In order to insure the proper rate of applica-
tion, all spray and granular applicators must be calibrated prior to
operation. Manufacturers of equipment provide manuals and instructions
giving the proper procedure to use, and since the types of equipment
available are quite diverse, the details of calibration procedures can-
not be discussed here. However, some of the problems associated with
calibration of equipment are worth noting.
First, not all operators calibrate their equipment since some are
unable or unwilling to follow the rather complicated procedures, preferr-
ing to rely on their own judgment and experience. Those farmers who fol-
low these practices sometimes find that the first tankful of pesticide
has been applied at an excessive rate, and belatedly adjust the rate of
application for the next tank.
Second, the rate of application depends primarily on the nozzle
size, nozzle spacing, discharge pressure (for sprays), and forward speed
of travel. Once the nozzles are in place and the pressure has been set,
the application rate depends upon the forward speed. If the speed of cal-
ibration is faster than the application speed, overapplicatioh will result
during crop treatment.
Third, many spray calibrations are made with water (which is often
recommended by the manufacturer). This practice can cause difficulties
because the viscosity or density of the pesticide formulation often var-
ies from that of water; the application rate of the pesticide could be
higher than that of the water. In these cases, the equipment should be
rechecked or recalibrated with the pesticide at the beginning of crop
treatment.
The same argument holds true for granular pesticides. Calibration
must be performed for each granular formulation since the rate of appli-
cation varies widely for granules of different sizes, shapes, and densi-
ties. Problems develop when the same application rate is desired for a
different formulation than the one previously applied, and rather than
recalibrate the equipment, the same setting is used. This generally re-
sults in an erroneous application rate.
27
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Fourth, once the calibration has taken place, the nozzles, nozzle
arrangements, pressures (for sprays), and formulations should not be
changed without recalibration. If any of these factors change (i.e., a
higher pressure is desired for good coverage), a risk of overapplication
results if recalibration is not done. The tendency is not to recalibrate
after application has begun, especially in cases where the farmer is
operating on a tight schedule.
Finally, mathematical miscalculations can occur at the time of cali-
bration, and the actual application rate be different from the calculated
(intended) one. This results from human error, and is, to an indeterminate
degree, inherent in the process.
Forward Speed of the Unit - During treatment the rate of pesticide appli-
cation varies inversely (though not always proportionally) with the for-
ward speed of the unit. To apply the chemical to the crop at a constant
rate requires maintaining a constant speed. This, however, is difficult
to do under certain conditions.
Overapplication occurs when the vehicle is operated slower than is
required. This commonly occurs when operating on uphill slopes, turning
around, or encountering obstacles. Many units can be shut off by the
operator when encountering obstacles or turning around, and this practice
is common, though not universal. However, on uphill slopes the crop must
be treated, and unless a constant speed is maintained, overapplication
will occur when the applicator slows down. Conversely, an excessive speed
may cause underapplication and poor pest control, a result which may lead
the farmer to overcompensate (by using higher application rates) the next
year.
Height of the Spray Boom - Ground spray-application booms that hold the
nozzles and dispense the pesticide must be operated at the proper height.
Since nozzles are normally designed to dispense the pesticide at a high
rate directly beneath, and at a lower rate at the periphery of the spray
pattern, a 50% overlap between nozzle spray patterns is frequently used
to provide uniform coverage. Once the nozzle spacings are fixed on the
boom then, the height of the boom determines the distribution pattern.
Whenever using fan-spray, solid-cone, or hollow-cone nozzles, the
distribution pattern of the spray is affected less by having the boom
too high than by having it too low. High boom settings cause excessive
overlap, while low boom settings cause insufficient overlap. Excessive
overlap does not distort the spray application pattern as much as in-
sufficient overlap.^.' Therefore, when the proper boom height is in doubt,
it is better to have it too high than too low. Unfortunately, in consid-
ering drift, the reverse is true. In either case, however, the improper
boom height will cause nonuniform distribution.
28
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Improper Pesticide Formulation - Miscalculations on the part of the
farmer, misinterpretations of the label recommendations, or improper mea-
surements can cause the concentration of the mixed formulation to be in
error. When the concentration is higher than that intended, overapplica-
tion will result. Occasionally this will occur as humans are subject to
error. However, economics plays an important part in farm operations, and
the cost-consciousness of farmers is a good deterrent to the use of im-
proper formulations, and from this point of view, keeps overapplication
at a minimum.
Aircraft Spray Distribution - Fixed-wing aircraft flying at low levels
have wide variations in the spray deposit pattern on the ground beneath
them Figures 3 through 5.12/ show some examples of how the spray distri-
bution from aircraft is nonuniformly distributed across the swath. In
Figure 3 the nozzles are evenly spaced, while in Figure 4 the nozzles
are both unevenly spaced and absent from the center of the boom. Figure
5 compares a coarse spray pattern and a medium spray pattern. Notice that
in all cases the distribution is nonuniform.
Attempts have been made to overcome this problem and improve the uni-
formity of the spray distribution across the swath. Both irregular and
asymmetrical spacings of nozzles, and combinations of nozzles across the
boom producing coarse and fine sprays, have been tried with some success
but the problem still exists. The spray pattern from a boom may be uni-
form in the laboratory, but when the boom is mounted on an airplane and
subjected to crosswinds in the field, the pattern becomes distorted.
To add to the problem, the deposit pattern along the line of flight
of the aircraft is irregular, also. Studies conducted on this subject
have shown that the amount of spray deposited in high dosage areas is
commonly four to five times greater than the amount deposited in low dos-
age areas.il/ Clearly, this represents a nonuniform distribution of pes-
ticide sprays of large magnitude, considering the amount of aerial spray
applications performed on crops each year. The problem, however, appears
to be insolvable, since no nozzle arrangement or spacing can accommodate
the many atmospheric disturbances that exist in actual field operations.
Quantification of Overapplication and Nonuniform Distribution
It should be apparent that the mechanisms which cause overapplica-
tion and nonuniform distribution discussed in this section defy quanti-
fication in the strict sense. The nonuniformity of distribution caused
by metering devices, nozzles, and poor tank agitation have been studied
and quantified in some cases, as previously discussed; however, to at-
tempt to quantify factors such as the type of metering devices used, the
29
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A .:,,., ./., .^., ^-, ,^
25 20 /S 10 5
FEET LEFT OF CENTER
S 10 15 20 25
FEET RIGHT OF CENTER
Figure 3. Spray distribution at a 2-ft flight level from evenly
spaced nozzles on a high-wing monoplane.
25 20 15 10 5
FEET LEFT OF CENTER
5 10 IS 20 25
FEET RIGHT OF CENTER
Figure 4. Spray distribution from unevenly arranged nozzles
(none in the center boom section) on a high-wing
monoplane at a 1- to 2-ft flight level.
Source: Chamberlin, J. C. et al., "Studies of Airplane Spray-
Deposit Patterns at Low Flight Levels," USDA Technical
Bulletin No. 1110, May 1955.
30
-------
SO 45 40 35 30 25 20 15 10 5 C 5 10 15 20 25 3O 35 40 45 SO
Wl.
VO .5
MPit
50 45 40 35 30 25 20 15 10 5 C 5 10 IS 20 25 30 35 4O 45 SO
FEET LEFT OF CENTER FEET RIGHT OF CENTER
Figure 5. Spray-distribution curves for applications at a 2-ft flight
level from 30 evenly spaced nozzles on a Stearman biplane:
A, coarse spray; B, medium spray.
Source: Chamberlin, J. C. et al., "Studies of Airplane Spray-Deposit
Patterns at Low Flight Levels," USDA Technical Bulletin
No. 1110, May 1955.
31
-------
number of nozzles that clog or wear out during application, and the num-
ber of tanks that are improperly agitated would require time and data far
beyond that presently available. Quantification of operational factors
is even more difficult.
The problems of overapplication and nonuniform distribution, then,
must remain in the form of qualitative, semiquantitative descriptions.
The importance of these two problems should not, however, be considered
negligible or of no concern to inefficient pesticide use in agriculture.
It is a current and future problem with which those involved must deal.
Unfortunately, the degree to which the problem exists defies more pre-
cise definition at present.
PESTICIDE DRIFT
Pesticides are lost into the environment at the time of application
when they drift away from the crop being treated. Under certain circum-
stances, the losses are substantial, and pose both an immediate and long-
term hazard to the surrounding environment. The extent of drift cannot
be considered either accidental or uncontrollable. Losses of pesticide
because of drift at the time of application are wasteful.
Drift is a rather complex mechanism which is determined by a variety
of interrelated factors. In this section the general parameters and fac-
tors which affect drift are examined as well as more specific details on
the parameters that affect drift and the potential of its occurrence.
Following this discussion the likelihood of pesticide drift in various
agricultural operations is examined in detail, and estimates of the per-
centage of pesticide lost in each operation is given. Finally, the quanti-
ties of pesticides lost during pesticide application to the three study
crops—corn, sorghum, and apples—are estimated for the year 1971.
The sections which follow are:
1. General Drift Parameters;
2. Specific Drift Parameters;
3. Likelihood of Pesticide Drift in Agriculture; and
4. Estimated Pesticide Losses Due to Drift From the U.S. Corn,
Sorghum, and Apple Crops (1971).
32
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General Drift Parameters
Once a particle is released into the air during pesticide applica-
tion, its movement is subject to both gravitational and aerodynamic drag
forces in accordance with Newton's second law of motion: force = mass x
acceleration. Drift, as defined for this discussion, originates when
forces acting on the particle move it in the wrong direction, and the
particle ends up in a location 1,000 ft or more from the target area.
The basic parameters which influence the occurrence and extent of par-
ticle (or droplet) drift are the properties of the particle and the
meteorological conditions to which it is subjected. Each of these param-
eters is discussed below.
Particle Properties - The most important property affecting the suscep-
tibility of a particle in air to aerial transport is its size. Two other
variables, density and shape, have a much lesser effect, but nonetheless
must be taken into consideration once the particle size is given. These
two lesser variables are discussed first.
Particle density - Particle density is determined by the density of
the formulation. Solid formulations (dusts and granules) have a specific
gravity greater than that of water, ranging from 1.3 to 3.0, with a typi-
cal value of 2.5. Liquid formulations have specific gravities ranging
from 0.8 for oil carriers to 1.2 for some materials, with the typical
value of 1.0 (since most applications use water as the carrier).H' Spe-
cific gravities of less than 0.7 and greater than 1.3 are rarely encount-
ered in liquid formulations..!!'
Density affects the rate at which particles fall in air due to grav-
itational forces. All other variables being equal, a particle with a
higher density is less susceptible to drift than a lighter one. On the
basis of density alone solid formulations are less susceptible to drift
than are liquid ones. To minimize drift, then, a high density is desir-
able.
Particle shape - Particle shape affects the fall of the particle
since aerodynamic drag forces acting against fall counteract the grav-
itational forces. As the particle accelerates toward the earth, the aero-
dynamic forces will eventually counterbalance the gravitational forces,
and a constant (terminal) velocity will be reached. Drift susceptibility
is reduced as the terminal velocity of a particle increases, since the
time it remains airborne for a given distance of fall is reduced.
33
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Particles of an irregular shape have lower terminal velocities than
spheres, although these effects are variable. (For example, a bullet-
shaped particle would be better than a sphere.) If solid pesticides are
formed in smooth spherical shapes rather than irregular ones, the drift
is generally reduced. Liquids, on the other hand, assume different forms
when dispersed into the air. Water droplets have similar terminal veloci-
ties to those of rigid spheres, and other liquids are deformed from aero-
dynamic forces and internal circulation.il/ In the case of liquids, high
density, high surface tension, and low viscosity minimize drop deforma-
tion and, thus, increase the terminal velocity.ii.'
Particle size - Although density and shape have an affect on the
drift potential of particles, by far the most important particle prop-
erty is its size. Agricultural pesticides are dispersed into the environ-
ment during crop treatment in sizes ranging from as little as 1 p, to over
2,000 p,. When the lesser effects of density and shape are equal for dif-
ferent particles, the drift potential increases greatly as particle size
decreases.
Particle size is related to the type of formulation used. The formu-
lations most commonly used in agriculture are dusts, granules, and sprays.
Each of these formulations is examined separately.
Dusts - Particle size for dusts, as previously mentioned, is
determined primarily by the manufacturer. Dust concentrates are normally
screened to a range of 1 to 25 p,, with a stated average of 80 to 90% of
the formulation below 25 p..!/ The number median diameter, NMD (the median
diameter that divides the formulation into two equal portions on the basis
of the number of particles), ranges from 1 to 10 p for most commercial
dusts.8,7 Field-strength dusts are prepared with particle sizes ranging
from 30 to 50 p,.!/
Granules - Granules are produced by impregnating, dry mixing,
or adhesive binding a carrier with pesticide, and then carefully screen-
ing the particles to size. The size range is commonly 16/30 to 30/60 mesh
(U.S. standard sieves*), making the granule size range from 1,190 to
250 p,..§/ Particles in this range, particularly the dense solid granular
particles, are not subject to drift to any extent.
* Note: The sieve opening sizes for 16-, 30-, and 60-mesh U.S. stan-
dard sieves are 1,190, 595, and 250 p,, respectively. A 30/60
size range means the screened material will pass through a
30-mesh screen but not through a 60-mesh screen.
34
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Sprays - The sizing of spray droplets is not determined at the
time of formulation, as with dusts and granules, but at the time of ap-
plication. For this reason, spray droplet sizes vary widely from aerosols
to globules. Many factors determine the size of droplets at the time they
are dispensed into the environment. These factors not only determine the
size of the particles, but their drift potential as well.
Before beginning the discussion on droplet size, the term
volume median diameter (VMD) needs to be introduced. Since a spray is
actually a spectrum of different size droplets, VMD is used to designate
the average droplet size of the spray spectrum in terms of a median di-
ameter. The VMD divides the droplet spectrum into two portions such that
the total volume of all droplets smaller than the VMD is equal to the
total volume of all droplets larger than the VMD.
The most important variables affecting the size of spray par-
ticles are: (a) nozzles--types, sizes, and orientation; (b) discharge
pressure; (c) liquid properties--viscosity, vapor pressure, density, and
surface tension; and (d) additives and formulations. The following dis-
cussion shows the relative importance and effect of each variable on par-
ticle size.
Nozzles - A wide variety of nozzles is available for spray ap-
plicators. The types of nozzles most commonly used on agricultural ground
or aircraft equipment are fan, cone, jet, and flooding. The fan nozzles
are most commonly used on ground equipment, but to a limited extent are
also used on aircraft. Cone is the most common nozzle type mounted on air-
craft. The flooding and jet nozzles are used on ground and aircraft equip-
ment, respectively, to produce coarse spray droplets. Droplet size depends
upon the discharge pressure, orifice size, nozzle orientation, and nozzle
type. For common use the drop sizes produced by each type of nozzle are:
fan and cone, 125 to 500 g, VMD; and jet and flooding, 600 to 1,000 M-
VMD. W
Orifice size on the commonly used commercially available aerial
spray nozzles ranges from 0.041 to 0.25 in._' For a given pressure, the
droplet VMD increases as orifice size increases, though not proportionally.
Doubling the area may increase the VMD by 10 to 30%.£/
Orientation of the nozzle is important in aircraft spraying.
On fixed wing aircraft, a nozzle pointed downward (vertical) produces a
finer spray droplet size than when pointed back (with the airstream) for
normal water diluted sprays. On helicopters, the reverse is true; that
is, a nozzle pointed down (vertical) produces a coarser spray than one
35
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oriented at an angle to the vertical. To demonstrate this effect, Yates
et al. (1964).16_/ performed tests with an SSD6-46 (cone) nozzle oriented
vertically and oriented back on agricultural dispersement equipment
mounted on a modified Stearman aircraft. With the nozzle directed back, •
the droplet size produced was 420 jj, VMD compared to 290 p, VMD with the
nozzle directed down.
Discharge pressure - Nozzle discharge pressures can vary widely
in agricultural pesticide applications. Aircraft, both fixed and rotary
wing, can use liquid discharge pressures between 10 and 60 psi; ground
rigs spraying the soil, or plants, can operate between 10 and 120 psi;
and orchard sprayers use pressures up to 800 psi (for high volume spray-
ing of 400 to 600 gal/acre). The effect of discharge pressure on spray
droplet size is to increase the VMD as pressure decreases for a given
hydraulic nozzle—though this relation varies from nozzle to nozzle, and
data from various sources are inconsistent. Generally, a reduction in
pressure of 50% in the range of 25 to 100 psi on a hollow cone or fan
spray nozzle increases the VMD by about 10 to 30%. Other investigations
have shown that with disc-type hollow cone nozzles at pressures above
100 psi, the VMD varies as the inverse square root of pressure.^./
Liquid properties - The most important properties affecting the
size of a droplet are: (a) density; (b) surface tension; (c) viscosity;
and (d) vapor pressure. At the time the droplets are formed in agricul-
tural spray systems, the first three properties affect the particle size,
while vapor pressure has no appreciable effect. After the droplet is
formed the vapor pressure predominates since it affects the rate of evap-
oration and, therefore, the change in the particle size with time.
Density has little effect on the droplet size produced in agri-
cultural spraying since spray formulations have a small range of specific
gravity (0.8 for oil carriers to 1.2 for other materials). The effect of
density on droplet size formation in aircraft is to decrease the drop
size as the liquid density increases. This relationship is caused pri-
marily by the slipstream air effects.jL/
Surface tension is the force of a liquid that resists the form-
ation of a new surface. When a droplet is first formed, the newly formed
surface has a dynamic surface tension that changes with time. The droplet
eventually reaches equilibrium and at this point the static surface ten-
sion is established, which is normally referred to as the "surface ten-
sion." It is the dynamic surface tension, i.e., that which evolves at the
197
time of atomization, that should be used to predict drop size.—' An in-
crease in dynamic surface tension has been shown to increase the amounts
of spray deposit, while at the same time increases the size of the drop
in aircraft spray.i/
36
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Viscosity has an important and significant effect on the drop-
let size spectrum. A high viscosity reduces the proportion of small drops
initially present in the spray emitted from any given nozzle,i±.' thereby
increasing the spray drop VMD. Also, once droplets are formed by aircraft,
they are subject to secondary breakup which will increase the droplet spec-
trum, reducing the drop VMD. The higher the viscosity of the fluid, the
less likely secondary breakup will occur since a higher viscosity delays
drop disintegration, thereby increasing VMD.
At the time liquids are released by aircraft into the airstream,
they are subjected to a high shear force. The viscosities of simple New-
tonian fluids such as water, are unaffected by the shear rate, while the
viscosities of complex, or non-Newtonian fluids are a function of shear
rate. Many of the drift control agents developed recently to increase the
viscosity of the liquid formulation are non-Newtonian fluids, and the
shear rate has an important effect on their performance. The high shear
rate at the time of release makes the apparent viscosity of liquids con-
taining these control agents low (apparent viscosity decreases as shear
rate increases) in the range of simple fluids that are normally used in
spray formulations. Once the droplets are formed, there is very little
secondary breakup since the apparent viscosity increases dramatically as
the shear rate falls. However, the advantage of larger drop formation by
the increased viscosity of the fluid containing the control agents is re-
duced if the nozzles produce a high shear rate on the film formed by the
nozzle. Therefore, the type of nozzle critically affects the drop size
distribution of high viscosity non-Newtonian fluids.j^./
Vapor pressure of the liquid has no apparent effect on the in-
itial drop size spectrum of the common agricultural sprays.ii/ However,
once the droplets are formed and are dispersed into the air, vapor pres-
sure has the most important effect on the size of a drop during its flight
to the target, since the vapor pressure affects the rate of evaporation
of the particle—the lower the vapor pressure, the lower the rate of evap-
oration.
The importance evaporation has on particle size, and, therefore,
drift cannot be overemphasized. Since drop size is one of the most impor-
tant parameters affecting drift, and evaporation directly affects the drop
size with respect to time, the subject of evaporation will receive further
consideration in the section on specific drift parameters.
Additives and formulations - Numerous additives and formula-
tions have been developed to control the size of drops formed when spray-
ing. The additives and formulations are employed to increase viscosity,
increase surface tension, or lower the vapor pressure of the liquid form-
ulations commonly used.
37
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Additives are used to reduce evaporation and increase surface
tension in water formulations. Tests show that a 30% (by weight) suspen-
sion of solids in water in an atmosphere of 104°F and 20% relative hu-
midity results in drops of 150 ^ becoming dusts while falling 20 ft. Under
similar conditions, amine stearates added to the solution greatly reduce
evaporation and 80 p, drops show no detectable evaporative loss during
fall..i/ Long-chain fatty acids and salts of volatile bases incorporated
into the spray liquid have also been shown to reduce the evaporation of
falling drops.il/
Spray viscosities can be modified (increased) by the use of
thixotropic gel, hydroxyethyl cellulose, particulate sprays, and emul-
sions, both normal and invert. Emulsions of oil-in-water (normal) and
water-in-oil (invert) are both used in agriculture today, while the other
control agents have limited use. Liquid ratios in normal emulsions are
usually 1:9, oil-in-water (0/W), while invert emulsions are at least 8:1,
water-in-oil (W/0), and often higher.1!13/ Both types of emulsions in-
crease the viscosity and reduce the evaporation of the formulation when
compared to a simple, water-only formulation. Invert emulsions, however,
reduce the evaporation substantially since water is the dispersed phase
(surrounded by oil). Inverts have become more popular since the develop-
ment of a Bi-Fluid Spray System, which permits satisfactory application
of W/0 emulsions in any desired phase ratio.—'
Meteorological Conditions - Pesticide particles released into the air
during application are subject to drift from the target area as a direct
result of aerial transport by atmospheric movement. Those meteorological
conditions which most affect drift are: (a) wind direction and velocity;
(b) turbulence; (c) relative humidity and air temperature; and (d) atmo-
spheric stability. Each of these factors is examined below.
Wind direction and velocity - The direction the wind is blowing de-
termines the direction of drift. Determining wind direction in the pres-
ence of adjacent crops or vegetation susceptible to damage by the pesti-
cide in use is important in insuring that drift into the neighboring
areas can be avoided.
Wind speed varies with different atmospheric stability conditions
and imparts the lateral movement to particles in air. The average wind
speed as well as the wind velocity gradient, are important in determin-
ing drift. The velocity gradient is the decrease in wind speed with
This is no longer true in the United States. The initial enthusiasm
over invert emulsions has died out, since there are too many tech-
nical difficulties involved in their use and in their adaptability
to normal spray techniques.
38
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height from the overhead boundary layer down to some point above the
ground where the wind speed reaches zero. This profile varies with atmo-
spheric stability and surface roughness and is important in trying to
determine the effect of wind transport of particles near the ground sur-
face. The potential for drift increases as wind speed increases. -i^.'
Turbulence - Turbulence is a series of horizontal and vertical gusts
and lulls, and random eddy movements of the air. It is dependent upon
ground roughness, mean wind speed, and thermal stability of the air. Tur-
bulence is one of the most important factors affecting drift since the
combined forces of gravity, wind speed, and turbulence transport airborne
particles.
Turbulence in a vertical direction is minimum under very stable
atmospheric conditions (inversions), and consists mostly of horizontal
eddy movements. Under unstable conditions vertical turbulence is maxi-
mized, and the upward projection of particles from vertical wind gusts
makes the drift potential high. Therefore, common practice is to char-
acterize the degree of turbulence and, therefore, the potential for
drift, by referring to the stability ratio (S.R. ), which is mathemati-
cally defined as
„ n
S.R. = 105
o .
where T, and To are the temperatures, in C, measured at 8 and 32 ft
above the ground, respectively; and u is the mean horizontal wind ve-
locity, in centimeters per second. The atmospheric conditions are classir
fied into the following categories: very stable, S.R. greater than 1.2;
stable, S.R. 0.1 to 1.2; nearly neutral, S.R. -0.1 to 0.1; and unstable,
-0.1 or less. Therefore, when a high S.R. exists, drift potential is de-
creased under the stable conditions, whereas with a negative S.R., the
drift potential is high under the unstable conditions.
Relative humidity and air temperatures - Relative humidity and air
temperature can affect the rate of evaporation, and thus, the particle
size of the liquid droplets. Both have an effect on water base drops,
while only temperature affects nonaqueous liquid evaporation rates. A
higher temperature increases evaporation rate, as does a lower humidity.
The effect of temperature and relative humidity on water droplets is
shown in Table 3,12.' which gives the lifetimes and approximate height
through which three different sized drops would fall before complete
extinction.
39
-------
Table 3. LIFETIME AND FALL OF WATER DROPS THROUGH AIR
Initial diameter
of drop (u)
200
100
50
20 °C
200
50
12.
, 80%
sec
sec
5 sec
Ambient
RH (AT = 2.2°C)
268 ft
22 ft
5 in.
air conditions
30 °C, 50%
56 sec
14 sec
3.3 sec
RH (AT = 7.7°C)
69 ft
6 ft
1-1/4 in
Source: Amsden, R. C., "Reducing the Evaporation of Sprays," International Agricultural
Aviation Center, The Hague, Agricultural Aviation, 4:88.
-------
Atmospheric stability - The stability ratio was previously defined
and its magnitude indicates the degree of atmospheric stability. The very
stable condition is known as an inversion, which occurs when the overhead
layer of air is warmer than the air at ground level. This condition is
characterized by low wind velocities, a small velocity gradient, and lit-
tle or no vertical turbulence. On the other end of the spectrum is the
unstable (lapse) condition which has a higher ground layer temperature
than the overhead layer. This condition is characterized by high wind ve-
locity, a large velocity gradient, and considerable vertical and hori-
zontal air turbulence mixing. The intermediate (neutral) condition shows
no change in temperature with height, milder winds, and milder tutbulent
conditions than does the unstable condition.
The conditions which predominate occur at different times of day.
Neutral and lapse conditions prevail during the daytime when the sun is
bright, while inversions occur during early morning hours, evening hours,
and nighttime. On days when the sky is overcast, the temperature gradient
will vary from an inversion to a neutral condition.—'
Therefore, high turbulence is primarily a daytime phenomenon since
turbulence is inversely related to the stability ratio. The drift poten-
tial of pesticides during application is lower under the stable condi-
tions normally occurring in the morning or late evening hours, and,
generally, these times are best for crop treatment with a minimum of
drift.
Specific Drift Parameters
Briefly summarizing the previous section, we find that the most im-
portant factors determining the incidence of drift are: (a) particle
size; and (b) wind speed and turbulence. This section deals with specific
parameters affecting the quantity of drift involved at the time pesti-
cides are released into the environment. The factors considered in this
section, then, deal not only with the parameters just discussed, but
with other important aspects of drift as well.
To quantify the amount of drift expected under various circumstances,
a number of factors must be considered. They are:
1. Sedimentation and impaction;
2. Sedimentation and drift;
3. Impaction and drift;
41
-------
4. Spray particle size spectrum;
5. Spray particle evaporation; and
6. Drift potential quantified.
This section concludes with estimates on the quantities of drift
potential based upon the information presented here and in the previous
section. These estimates are used extensively in the section "The Like-
lihood of Pesticide Drift in Agriculture."
Sedimentation and Impaction - The objective of applying any agricultural
chemical is to place the chemical in the right place and in the right
form. Pesticides applied to crops have one of two basic targets—the
crop soil or the crop plants. When the pesticides are released, there
are several ways by which the particles or droplets are collected on the
intended target. They are:
1. Sedimentation upon horizontal surfaces;
2. Impaction upon vertical surfaces;
3. Interception; and
4. Attractive electric forces.
Sedimentation and impact ion are by far the most important mecha-
nisms of particle deposit, and are the only mechanisms considered here.
Interception (in which the trajectory of a particle is such that the
center misses the obstacle, but, because of its finite size, the parti-
cle nonetheless comes into contact with the obstacle, and is collected)
becomes appreciable when the target and particle are of comparable size,
such as when contact insecticides are used on insects.lx' Since the con-
cern here is with pesticides applied to soils or plants, the effect is
negligible. Attractive forces are small also unless an electrostatic
charge is put on the particles (as is sometimes done in dust applica-
tions).
Sedimentation is simply the settling of a particle in the air onto
a horizontal surface, usually the soil. Pesticides released into the air,
whether from a height of 6 in. or 20 ft, are attracted by gravitational
forces and settle toward the earth. They accelerate until they reach a
constant velocity known as the terminal velocity. Particle resistance to
drift is directly related to this terminal velocity since the time the
particle remains in the air is dependent upon this velocity. As terminal
velocity increases, the drift potential decreases.
42
-------
Impaction is the collection of a particle carried in an airstream
upon the vertical surface of an object. Pesticides released into the air
are subject to diversion from their vertical path towards the earth by
horizontal movement, whether caused by wind or by intentionally project-
ing the particles in a certain direction (as when spraying). The parti-
cles tend to follow a divergent flow around the target and not to impact.
The degree to which impaction occurs is referred to as the irapaction ef-
ficiency, expressed as a percent of the particles collected to those that
would have collected on the object had they not been deflected from their
original course.
Sedimentation and impaction are now considered with relation to par-
ticle size to determine the effect this size has on these two mechanismss
and ultimately, the effect on the drift potential.
Sedimentation and Drift - Sedimentation is important since many pesti-
cides are released above the target obstacle and will not be deposited
on the intended surface unless sedimentation takes place. The dominant
factor determining the fall of particles in air is their size. Table 4.I2/
shows the effect of particle size on the terminal velocities of rigid
spheres (sp. gr. = 1.0), heavier rigid spheres (sp. gr. = 2.5), and water
droplets (sp. gr. = 1.0).
This table shows that the terminal velocity of particles increases
with size and density, and phat water droplets behave similar to solid
particles. Solid agricultural pesticides have a typical specific gravity
of 2.5 and agricultural sprays (mostly water diluted) have a typical spe-
cific gravity of 1.0. The terminal velocities shown in the table then,
apply to the pesticides used in agriculture.
The particle size most critical for sedimentation to take place
without drifting is dependent upon the height of release above the tar-
get surface, the particle density, and the wind speed and turbulence.
Release height can vary from 20 ft to 6 in., depending upon the appli-
cation method. The wind speed varies in a wide range, but will normally
be below 10 mph during pesticide application, and is assumed to have an
average value of 3 to 5 mph. Turbulence varies with the stability ratio
and is quite unpredictable. However, we will assume relatively low tur-
bulence accompanies the typical wind speeds used.
The effect terminal velocity has on falling particles and their
drift potential is shown more clearly by Tables 5 and 6. Each table shows
the amount of time it takes particles of various sizes with a given spe-
cific gravity to fall a certain distance. The longer a particle takes to
fall, the more susceptible it is to drift from varying wind speeds and
turbulence. These tables assume no turbulence.
43
-------
Table 4. TERMINAL VELOCITIES OF PARTICLES IN AIR
Rigid sphere . Water droplet
(sp. gr. = 1.0) (sp. gr. = 2.5) (sp. gr. = 1.0)
Diameter (yt) (ft/sec) (ft/sec) (ft/sec)
1 0.00011 0.00028 0.0001
10 0.01 0.025 0.01
50 0.25 0.63 0.25
100 0.85 1.8 0.89
200 2.4 4.6 2.4
300 3.9 7.5 3.8
400 5.3 10.0 5.3
500 6.8 .12.5 6.8
1,000 13.3 23.0 13.2
Source: Yates, W. E., and Akesson, N. B., "Reducing Pesticide Chemi-
cal Drift," Pesticide Formulations, Marcel Dekker, Inc.,
New York, p. 282 (1973).
44
-------
Table 5. TIME REQUIRED FOR A SOLID PARTICLE TO FALL A GIVEN DISTANCED
(sp. gr. = 2.5)
Particle
Release height (ft)
diameter (u)
1
10
50
100
0
30
20
0.8
0.3
.5
min
sec
sec
sec
1.5
90
1
2.4
1
min
min
sec
sec
3
180
2
4.8
2
10
min 600
min
sec
sec
6.7
16
5.6
min
min
sec
sec
20
1,200
13.4
32
11.1
min
min
sec
sec
a/ Assumes no turbulence.
Table 6. TIME REQUIRED FOR A PARTICLE TO FALL A GIVEN DISTANCED
(sp. gr. = 1.0)
Particle
Release height (ft)
diameter (u) 0.5 1.5 3 10 20
1
10
50
100
75 min 226 min 450 min 1,515 min 3,030 min
50 sec 2-1/2 rain 5 min 16.7 min 33.3 min
2 sec 6 sec 1 12 sec 40 sec 1.3 min
0.6 sec 1.7 sec 3.5 sec 11.6 sec 23 sec
a/ Assumes no turbulence.
-------
Considering that 10 sec in the air allows particles enough time to
become subject to the vagaries of wind turbulence and speed, the lines
show those small particles which remain above the target approximately
10 sec or more after release. Therefore, the particle size below which
the drift potential is very high is 50 p, for aircraft (typical release
height 5 to 20 ft) and 10 to 20 p, for ground equipment. Larger sized par-
ticles also have drift potential, but this potential decreases rapidly
with size. At 100 p, the drift potential for ground applications is vir-
tually nil, and for aerial applications it is also very small.
Further evidence is presented to show that the particle sizes above
are reasonable values:
1. Hartley (1959)JL§/ reported that particles under 50 p, diameter
"just make it" (to the ground) in upward winds (turbulence) of 1/6 mph.
2. Yates and Akesson (1973)JLfL/ reported that the distance required
for a water drop to reach its terminal velocity when falling in air is
less than 1 in. for particles less than 100 p,, 2 ft for 500 p. particles,
and 15 ft for 2,000 p, particles.
3. Table 7 shows the lateral distance particles will drift when re-
leased from both a 20 ft and a 10 ft height in wind speeds of 5 and 3 mph,
respectively, and no turbulence.
In summary, the evidence presented here shows that a particle whose
size is less than 50 p, has a very high drift potential in aerial applica-
tions, while a particle whose size is 20 p, or less has a very high drift
potential when released at a height of 3 ft or lower by ground equipment.
Impaction and Drift - Impaction depends not only upon the particle size
but the speed at which it approaches an object and the size of the ob-
ject as well. Figure 6 shows in graphical form a study by R. T. Jarman
(1957).—' This figure shows that: (a) as wind speed decreases, impaction
efficiency decreases; (b) as object size increases, impaction efficiency
decreases; and (c) as particle size decreases, impaction efficiency de-
creases.
This fact was further demonstrated by F. A. Brooks (1947)8/ and is
illustrated in Figure 7. This figure shows percent impaction efficiency
(called percent catch here) for droplets 100 p, and less at wind speeds
up to 100 mph. Forty micron droplets do not reach 100% efficiency at
speeds less than 100 mph.
46
-------
Table 7. THEORETICAL DISTANCE SOLID PARTICLE WOULD DRIFT IN 5 AND 3 MPH
WINDS FROM A HEIGHT OF 20 AND 10 FT, RESPECTIVELY-/
Drop diameter (u) (20 ft. 5 mph)-/ (10 ft, 3 mph)-/
1,000 11.0 ft (Not given)
500 21.6 ft (Not given)
400 (Not given) 8.5 ft
100 172.0 ft 48.0 ft
50 587.0 ft 178.0 ft
10 253.0 miles .84 miles
£/ Assumes no turbulence.
b/ Source: Ref. 12.
c/ Source: Ref. 1.
47
-------
40
30
20
10
I mm OIAHCHR
-T4RCCT I Cm DIAMETER-
WIND SPEED I m/i
10 20
30 40 SO 60 70
DROP SIZE MICRONS
BO
Figure 6. Efficiency of impaction of small droplets upon
cylinders at speeds of 1 and 4 m/sec.
Source: Courshee, R. J., "Some Aspects of the Application
of Pesticides," American Review of Entomology,
5:339 (1960).
48
-------
-m. diam cylinder
H-in. diam cylinder
2 3 456 8 10 15 20 30 40 50 60 80 100
Air-stream velocity, mph
Figure 7. Effect of droplet size and velocity of approach upon
the dynamic catch of two sizes of cylinders.
Source: Principles of Farm Machinery, Second Edition, The AVI
Publishing Company, Inc., p. 273 (1972).
49
-------
Since we have already assumed that typical wind speeds of 3 to 5
mph are experienced in agricultural pesticide applications, a table show-
ing the impaction efficiencies and drift potential of particles is con-
structed in Table 8. This table assumes an object size of 1/2 in. diameter
(such as a twig), and combines the data on the two graphs (which conflict
somewhat). The table demonstrates that particles 40 p. and below have very
high drift potential, while those 100 p, and above are much less suscept-
ible to drift.
Further evidence of the low impaction efficiency is found in the
literature and is presented here:
1. Splinter (1955)JL/ reported that failure to impact occurs with
particle sizes of less than 30 p,.
2. F. A. Brooks (1955)£/ reported that tests conducted with dusts
showed drift away from the treated area may be as high as 70% of the
total applied. (Note: dusts are particles whose diameter is less than
50 g,.)
In summary, the evidence presented here establishes the fact that
particles below 50 p, have a low impaction efficiency and are highly sub-
ject to drift. Combining this evidence with that on sedimentation gives
the following statements:
. All solid particles having a particle size of less than 50 p, have
a greater than 80% chance of drifting 1,000 ft or more in 3 to
5 mph winds when applied by aircraft flying at 10 to 20 ft over
the target.
All solid particles having a particle size less than 20 p, have
a greater than 80% chance of drifting 1,000 ft or more in 3 to 5
mph winds when applied by ground equipment from a height of 1.5
to 3.0 ft above the ground.
Up to this point only the size of an individual particle is consid-
ered. This applies to solids and liquids as well, but two other very im-
portant factors affect the particle size of liquids. The first is the
fact that all spray patterns have a range of particle sizes, or a spray
particle size spectrum. Once this spectrum of particles is released into
the air, the particles are subject to a decrease in size through the me-
chanism of evaporation. Each of these important subjects is considered
next.
50
-------
Table 8. IMPACTION EFFICIENCIES AND DRIFT POTENTIAL OF PARTICLES
IN 3 TO 5 MPH WINDS ON A 1/2-IN. CYLINDER
Particle
diameter (u)
10
20
40
100
Impaction efficiency (%) Drift potential
< 10% > 90%
< 10% > 90%
10-40% 60-90%
80% 20%
Note: Drift potential is the opposite of impaction efficiency. The
particles which do not impact are those that drift.
51
-------
Spray Particle Size Spectrum - The range of droplet sizes from a nozzle
under a given set of conditions is known as the droplet spectrum. The
spectrum is more important than the VMD size, since the drift potential
of a certain spray VMD is dependent upon the volume of small particles
produced. Although this subject has been studied intensively, no current
technology exists which will produce a single drop size from any nozzle,
and most nozzles, in fact, have a very wide range of droplet sizes.
Table 9_' shows the drop size distribution by volume of selected
drop size VMD's. These distributions are for aerially applied water-base
sprays commonly used in agriculture. Sprays using different liquids can
vary from the percentages shown there. An oil base spray will normally
have a smaller percent of small droplets than water, since the viscosity
is higher. Table 1012/ shows the size distribution of an oil sprayed from
a fern-type nozzle at 45 psi.
Notice that the VMD for the oil in Table 10 is in the 161 to 220 p,
range (approximately 190 p,), and that the percentage by volume of drop-
lets less than 100 p, is 7.34%, whereas, Table 9 shows that water base
sprays with a VMD of 130 and 278 p. have 15.8 and 6.0% of the volume in
droplets below 100 p,, respectively. The two types of sprays, then, have
comparable values, and Table 9 is referred to in most cases when discuss-
ing the drop size spectrum of a given VMD.
Water-in-oil (invert) emulsions and oil-in-water (normal) emulsions
display similar spectrums to those of water-base sprays. A studyi£/ of
the spectrums provided by a typical emulsion produced the information
given in Table 11. This table shows that emulsions having VMD's of about
900 p, have droplets less than 200 p, in the range of 1.0 to 2.5% by volume.
Table 9 shows that water sprays with a 900 p, VMD have a typical drop dis-
tribution of 5.0% by volume less than 220 to 240 p,. Emulsions, then, pro-
duce slightly fewer small drops than water-base sprays, but not appreci-
ably so. (Note: The distribution values of the water base sprays in
Table 11 are in good agreement with those in Table 9.)
In order to later quantify the likelihood of drift in agricultural
operations, it is useful to introduce the nozzles and their spray distri-
bution patterns provided by a large nozzle manufacturer, Spraying Systems
Company. Literaturel5»20/ provided by this company shows the nozzles
commercially available, rates of application, the droplet sizes each
nozzle produces at various pressures, and the spray distribution pattern
of each nozzle under laboratory conditions. This information is summari-
zed in Table 12, showing typical nozzles and application rates used in
agriculture. The associated drop VMD's, and percent of small particles
produced under laboratory conditions are shown with each type of opera-
tion at the given pressure.
52
-------
Table 9. DROP SIZE DISTRIBUTION (CUMULATIVE PERCENT BY VOLUME BELOW SIZES SHOWN)
< 50 um
Drop size Fine
urn microns aerosols
1 to 5 5
5 to 10 45
11 urn vmd 507.
10 to 15 77
15 to 20 97
20 to 40 100
40 to 60
60 to 80
86 um vmd
80 to 100
100 to 120
120 to 140
130 um vmd
140 to 180
180 to 200
200 to 220
220 to 240
240 to 260
260 to 280
280 to 300
278 urn vmd
300 to 350
350 to 400
400 to 450
460 um vmd
450 to 500
500 to 600
600 to 700
700 to 800
900 |im vmd
800 to 1,000
vmd 11 l»ra
Nozzle Cold
Type Fogger
5 Ib/in
Air
50 to 100 um 100 to 250 um 250 to 400 urn
Coarse Fine Medium
aerosols sprays sprays
0.1
0.4 0.1
2.0
2.
12.0 0.1
35.0 5. 2.
50%_
59.0 15.8 6.0
50%
100.
81.0 17.0
100.0 46.0
507.
92.0
100.0
86 pm 130 urn 278 urn
2-fluid Spinner 65015 Fan
30 Ib/in2 90 to 100 Down
Air mph Air 40 Ib/in2
90 to 100
No air- mph Air
stream
400 to 500 urn
Coarse
sprays
0.01
0.1
0.4
3.0
7.0
14.0
24.0
36.0
46.0
507.
55.0
74.0
88.0
96.0
100.0
460 urn
D6-46 Cone
Back
50 Ib/in2
90 to 100
mph Air
> 500 um
Very coarse
sprays
0.001
0.1
5.0
15.0
25.0
50%
100.00
900 Mm
D6-Jet Back
40 Ib/in2
90 to 100 mph
Air
The vmd or volume median diameter is that size of drop which divides the total volume of drops
found exactly in half. That is 507. of the volume is in drops above that size and 50% are below
the vmd size. The size is measured in micrometers abbreviated to pm and frequently called microns.
25,400 urn equals 1 in.
Source: Akesson, N. B., and Yates, W. E., "Physical Parameters Relating to Pesticide
Application," Personal Communication.
53
-------
Table 10. DROPLET SIZE DISTRIBUTION OF OIL DROPLETS SPRAYED
FROM A FERN-TYPE NOZZLE
Droplet
diameter (yQ Droplets by volume (%)
10 to 40 0.14
41 to 100 7.2
101 to 160 27.2
161 to 220 35.9
221 to 280 10.7
281 to 340 18.5
Source: Edwards, C. J., and Ripper, W. E., "Droplet Size, Rates of
Application and the Avoidance of Spray Drift, Proceedings
of the British Weed Control Conference, p. 350 (1953).
54
-------
Table 11. VARIATION OF DROPLET SIZE WITH NOZZLE TYPE AND PHASE RATIO OF 0/W AND W/0 EMULSIONS
Nozzle type
Ceramic V-jet
(Allman 12)
Ceramic V-jet
(Allman 6)
i
i
V-jet
(Spraying systems 5010)
Hollow cone
(Watson WG 4008)
Emission rate
(gal/min)
0.6
0.6
0.5
0.6
0.5
0.5
0.5
0.5
0.5
0.6
0.6
0.5
0.3
0.3
0.4
0.3
Emulsion
w/o
w/o
w/o
o/w
w/o
w/o
w/o
o/w
o/w
VI 1 0
w/o
water
w/o
w/o
water
water
Phase-ratio
water/ oil
13:1
9:1
6:1
8:1
10:1
8.5:1
6:1
10:1
5.5:1
12:1
7:1
-
9:1
4:1
-
-
Droplet
VMD (u)
1,620
1,480
1,300
630
840
950
700
490
360
1,280
925
515
1,200
870
420
370
Volume of
droplets (%)
< 200 u
0.2
0.5
1.0
3.0
0.6
1.6
1.6
5.2
12.0
0.2
2.5
5.8
0.5
1.0
10.0
8.6
Source: Coulthurst, J. P., et al., "Water-in-Oil Emulsions and the Control of Spray Drift,"
Symposium on the Formulation of Pesticides. S.C.I. Monograph No- 21, Society of
Chemical Industry (1966).
-------
Table 12.
VARIOUS NOZZLES, DROPLET SIZE VMD'S, AND SPRAY DISTRIBUTION
PATTERNS FORMED UNDER LABORATORY CONDITIONS AT STATED PRESSURES
Nozzle
D2-23
D5-23
D5-25
D10-45
D2-23
D5-45
D 10-45
9502E
9510E
9202E
9504E
8003
8003
8006
Dl-13
D2-13
D3-45
D10-25
Disc -type
Disc-type
Disc -type
Disc- type
Disc-type
Disc -type
Disc-type
95° Flat
95° Flat
95° Flat
95° Flat
80° Flat
80° Flat
80° Flat
Disc- type
Disc-type
Disc-type
Disc- type
Type
hollow cone
hollow cone
hollow cone
hollow cone
hollow cone
hollow cone
hollow cone
fan
fan
fan
fan
fan
fan
fan
hollow cone
hollow cone
hollow cone
hollow cone
Use*/
Helicoptor
Helicoptor
Helicoptor
Helicoptor
Airplane
Airplane
Airplane
Ground, band
Ground , band
Ground, broadcast
Ground, broadcast
Ground, broadcast
Ground, broadcast
Ground, broadcast
Ground , plants
Ground, plants
Ground , plants
Ground, plants
Gallons per
acreb/
0
1
2
6
0
1
2
7
37
21
42
16
22
31
2
3
9
40
.59
.1
.1
.6
.25
.0
.8
.4
.0
.0
.0
.0
.0
.0
.0
.5
.0
.0
Pressure
(psi)
50
50
50
50
50
50
50
40
40
40
40
20
40
20
50
50
50
50
Drop
VHP (>i)
200
255
300
470
200
270
390
375
575
375
420
430
390
550
150
170
260
410
Volume '
7, less
than the
specified size (u)
7
3
2
1
7
1
0
15
9
2
0
.57.
.07.
.57.
.07.
.57.
.57.
.57.
07.
07.
07.
07.
07.
07.
07.
.07.
.07,
.07.
.57.
<•
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
120
120
120
120
120
120
120
100
100
100
100
100
100
100
100
100
100
100
a/ Ground refers to applications made by ground equipment; band and broadcast are soil applications; and plants are foliar applications.
b/ Helicoptor with 45 mph speed, 45 ft swath, 22 nozzles; ground band with 4 mph speed, 14 in. band, height 7 in., 40 In. nozzle spacing;
ground broadcast at 4 mph, any nozzle spacing; ground plant, 4 mph, one nozzle/row, 40 in. row spacing; airplane at 90 mph, 60 ft
swath width, 24 nozzles.
-------
All of the information given in Table 12 is pertinent to the discus-.
sion on agricultural drift. The information in this table is used to show
the droplet VMD produced with typical agricultural ground equipment. The
statistics in Table 12 do not take into account the effects of wind speed
and shear in aircraft operations so that the values of the droplet spec-
trum distribution percentages given are slightly low. The droplet VMD
values are approximately correct (slightly low, also) and are used hence-
forth. Where the percentage drop-size spectrum below 120 p, in Table 12
disagrees with that given in Table 9 for a given droplet VMD, the value
in Table 9 is used. (Table 9 shows the percentage drop size distribution
by volume for aircraft operations.)
Tables 9 and 12 are now used to construct Table 13, which shows the
droplet size VMD's and droplet size spectrums produced in typical agri-
cultural operations. The importance of this table is apparent in a subse-
quent section when drift and VMD sizes are correlated.
The percentage of small droplets in a given drop VMD must be corre-
lated with evaporation to determine the drift potential for sprays.
Spray Particle Evaporation - The drop spectrum produced at the nozzle is
not the same as that arriving (or not arriving) at the target due to evapo-
ration. The effect of evaporation in relation to particle size is a very
steep variation in the life of a drop of volatile liquid with its initial
size. Under standard conditions the decrease of a droplet's surface area
by evaporation is approximately constant so that the reduction in volume
is inversely proportional to the square of the diameter. This means that
a 100 p, drop will evaporate to dryness in one-fourth the time a 200 p,
drop evaporates.JJ-L/
Evaporation effects on the lifetime and distance of fall before ex-
tinction of a water droplet are shown in Table 3 (p. 40). This table shows
that when the relative humidity is 50%, or lower, and the temperature is
60°F or higher, a 100 p, particle released from an airplane (over 7 ft
above the ground) will evaporate to dryness before sedimentation takes
place. This effect is illustrated graphically in Figure 8.—/ This graph
illustrates that 120 p, particles released from a height of 7 ft or more
will completely evaporate and that 150 p, articles will evaporate to dry-
ness at a height of 15 ft or more.
These two illustrations show the importance of evaporation on par-
ticle size. Using the data presented here, and in Table 6 (p. 45), which
shows the time required for a given size particle to fall a given dis-
tance, Table 14 is constructed to show the size of a particle at the time
of emission which will evaporate to less than 50 p, for aerial applications
and to less than 20 p, for ground applications. As previously stated, par-
ticles below these sizes are highly subject to drift.
57
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co
Table 13. WATER DROPLET SIZE VMD'S AND DROPLET SPECTRUMS PRODUCED IN CERTAIN AGRICULTURAL OPERATIONS
AS A FUNCTION OF NOZZLE TYPE, PRESSURE, AND APPLICATION RATE
Application
equipment
Helicopter
Airplane
Ground boom (band)
Ground boom (broadcast)
Ground boom (plants)
Nozzle
type
Cone
Cone
Cone
Cone
95° Flat fan
Flat fan
Flat fan
Cone
Cone
Gallons
per acre
0.6-1.0
1-5
0.2-1.0
1-5
10-40
< 10
10-40
3.5
10-40
Volume8./
ULV
LV
ULV
.LV
LV
ULV
LV
ULV
LV
Pressure
50
50
50
50
40
30
40
50
50
Drop
VHP (u)
200-250
250-500
200-250
250-500
350-600
300-40<£/
350-600
150-200
250-400
Drop spectrum
volume 7. less than the
specified size (u)
107. < 120
57. < 120
107. < 120
57. < 120
07. < 100
07. < 100
07. < 100
5-157. < 100
0.5-2.07. < 100
Note: Pressures of 50 psl are a little high for airplanes and ground booms (30-40 psi normal), but were the only pressures at which
the information was available.
a/ LV = low volume, ULV = ultra-low volume.
b/ Estimated.
-------
lottral movwn.nl in on. WPH wind. IM*
10 13 70
15 10
Figure 8. Evaporation rate of water droplets,
Source: Bowers, Wendell, "Reducing Drift of
Spray Droplets," OSU Extension
Facts, No. 1203.
59
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Table 14. SPRAY PARTICLES SIZES AT EMISSION THAT DRIFT
DUE TO EVAPORATION3./
Emission
diameter (n.) 0.5
10 X
50 X
80
100
120
150
Release height (ft)
1.5 3.0 10 20
X X X X
X X X X
X X X X
X X
X X
X
£/ Relative humidity, 50% or less; temperature 60 F, or above; wind
speed, 3 to 5 mph; low turbulence.
60
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Since the most common types of formulations used in agricultural
sprays are wettable powders, liquid concentrates, and emulsifiable con-
centrates, evaporation must be taken into account. Wettable powders are
solid dusts that are suspended in water. Liquid concentrates are soluble,
or emulsifiable to the point of being a solution in water, also. Emulsi-
fiable concentrates, which are liquid organic solutions containing the
pesticide, are emulsified into water. All of these formulations use water
as the carrier, and when the water evaporates, all that remains is the
pesticide dust or concentrate itself. (If the concentrate is volatile,
it will undergo evaporation, also.)
Clearly, then, the process of evaporation that takes place after a
droplet is emitted reduces its size and, consequently, increases the like-
lihood of drift for that drop. To summarize Table 14, the following state-
ments apply to the particle size and drift of sprays:
• All pesticide droplets in water carriers having an initial drop-
let size less than 120 p, have a greater than 50% chance of drift-
ing 1,000 ft or more in 3 to 5 mph winds when applied by aircraft
flying 10 ft or more above the ground.
All pesticide droplets in water carriers having an initial drop-
let size less than 80 ji have a greater than 50% chance of drift-
ing 1,000 ft or more in 3 to 5 mph winds when sprayed from ground
equipment from a height of 3.0 ft above the ground.
• All pesticide droplets in water carriers having an initial drop-
let size less than 50 ^ have a greater than 50% chance of drift-
ing 1,000 ft or more in 3 to 5 mph winds when sprayed from ground
equipment from a height of 6 in. above the ground.
What remains now is to combine the information presented to this
point into a table showing the relationship of particle size, release
height, and drift potential. This is done in the next section.
Drift Potential Quantified - To this point both solid formulations and
liquid formulations have been discussed. In quantifying the drift poten-
tial for liquids it is necessary to take into account evaporation and the
spray drop spectrum, while for solids it is unnecessary. For convenience
and clarity solid formulations and liquid formulations are discussed
separately below.
61
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Solid formulations - Agricultural pesticides are formulated both as
dusts and granules. The drift potential encountered when treating crops
with these solids is now summarized to show drift potential as a function
of particle size and height of release, since both formulations may be
applied with ground equipment or aircraft.
Using the information presented in Tables 4, 5, 7, and 8 on the pre-
ceding pages, Table 15 is constructed to show the drift potential of solids
as a function of particle size and height of release at wind speeds of
3 to 5 mph, and neutral atmospheric stability. Table 15 will be used in
all future estimates on drift quantities experienced during crop treatment
with dusts or granules.
Spray formulations - In order to quantify the drift potential of in-
dividual spray droplets on the basis of initial size at the time of emis-
sion, evaporation is considered since this decreases the particle size
as the droplet falls. In the case of small droplets (< 50 p,) the effect
is appreciable since they both evaporate faster and have lower terminal
velocities causing them to remain in the air longer.
The process of quantifying drift is done in two steps. First, the
individual particle sizes are examined for drift potential with respect
to initial particle size, height of release, and evaporation effects. The
information in Tables 3, 6, 7, 14, and 15 on the preceding pages, and
Figure 8 (p. 59) is used to construct Table 16. This table takes evapo-
ration into account, and the first three drop size VMD's are similar to
solids, since in this range they evaporate quickly. The 60-, 100-, and
120-p, sizes evaporate to dryness before sedimentation at the 10- and 20-
ft heights. The 60-p, size evaporates to dryness at the 3-ft height before
sedimentation. All other sizes at the associated release heights undergo
some evaporation, but very little in the low release heights and large
drop sizes. In the first 3 ft of fall, very little evaporation takes
place at 100 p, and above. This is why the drift potential falls rapidly
in the 0.5 to 3.0 ft range as size increases beyond 60 p,. The same rea-
soning holds for the large decrease in drift potential from 120 to 200 p,
at 10 and 20 ft. Evaporation effects are almost negligible for the 200 p,
droplet size at these heights.
Second, Table 17 is constructed from Tables 16, 13, and 9 on the pre-
ceding pages. The drift potential for each VMD range is approximated based
upon the percentage of particles found in the particle size ranges indi-
cated. The drift potential associated with aircraft producing sprays in
each size range is given.
62
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Table 15. DRIFT POTENTIAL AS A FUNCTION OF SOLID PARTICLE SIZE AND
HEIGHT OF RELEASE AT GIVEN METEOROLOGICAL CONDITIONS!/
Drift potential (7,)-'
Particle size
(u)
1
10
50
100
200
Height of release (ft)
0.5
95+
80
10
0
0
1.5 3.0 10
95+ 95+ 95+
85 95+ 95+
20 40 80
0 0 10
0 0 0
20
95+
95+
90
20
0
af Wind speed at 3 to 5 mph, and neutral atmospheric stability.
b_/ Drift -refers to a distance of 1,000 ft or more from the target area.
Table 16. DRIFT POTENTIAL AS A FUNCTION OF INITIAL DROP SIZE, HEIGHT
OF RELEASE, AND EVAPORATION-/
Drift potential
Initial drop
size at emission (u) 0.5
10
20
40
60
100
120
200
0.5
80
80
80
40
0
0
0
1.5
85
85
85
60
10
0
0
Height of
3
95+
95+
95+
70
20
10
0
release (ft)
12
95+
95+
95+
95
60
50
15
20
95+
95+
95+
95+
85
80
30
a/ Wind speed 3 to 5 mph, and neutral atmospheric stability.
b/ Drift refers to a distance of 1,000 ft or more from the target area.
63
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Table 17. ESTIMATED DRIFT POTENTIAL OF AIRCRAFT SPRAY AS A FUNCTION OF
SPRAY DROP VMD AT EMISSION AND HEIGHT OF RELEASED/
Spray drop
range VMD (p)
50
50-100
100-200
200-250
250-400
400-500
Over 500
Average volume^'
% below 100 u
100
60
20
10
3
0.1
0
Average volume^.'
% below
100 and 200 u
0
40
50
30
5
3
1
% Drift potential^/
Total volume
% below 200 u
100
100
70
40
8
3
1
Height of
10 ft
80
65
35
20
10
2
1
release
20 ft
90
75
50
30
15
5
2
a/ Wind speed of 3 to 5 mph; aircraft speed 90 to 100 mph; neutral stability.
b_/ Cone-type nozzles for spraying.
£/ Drift to 1,000 ft or more from target area.
-------
In the next section the type of equipment and method of pesticide
application on agricultural crops—with specific consideration given to
corn, sorghum, and apples--is examined, and the likelihood of drift is
quantified. Tables 9, 13, and 16 on the preceding pages are used to as-
sist in estimating the percentages of pesticide lost due to drift, and
are referred to frequently.
Likelihood of Pesticide Drift in Agriculture
The information examined and developed to this point is now applied
to the actual field conditions and operations experienced in agriculture.
The objective of this section is to develop the estimates of drift losses
that occur when pesticides are applied to crops, taking into consideration
the method of application, the application equipment, and the pesticide
formulations available.
A number of field tests have been conducted in the past by various
researchers to determine the amount of drift involved under various cir-
cumstances. Some of these studies are presented in Appendix A, and are
used as a source of information to assist in estimating the likelihood
of drift in agricultural pesticide applications. The information developed
previously and the field studies presented in Appendix A form the basis
for the estimates given later, which show a detailed picture of drift in
agricultural pesticide applications. In order to arrive at these estimates,
the following sections are discussed:
1. Agricultural applications of pesticides and drift; and
2. Drift from agricultural pesticide application—quantities.
Agricultural Applications of Pesticides and Drift - The crops grown in
the United States are diverse. Pesticides used to treat the crops are
available to agriculture in a wide variety of chemical compounds, formu-
lations, and mixtures. Application equipment available for dispensing the
pesticides onto the crops ranges from large, expensive aircraft to inex-
pensive backpack units. No study of agricultural pesticide applications
can cover the many methods used to treat the crops in the U.S.
The objective of this section is to discuss the most common methods
of pesticide application in agriculture presented earlier while giving
particular attention to the problem of drift associated with each tech-
nique. Attention is focused on field crops and orchards since the three
study crops are corn, sorghum, and apples. An estimation is made of the
65
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amount of drift accompanying each application procedure. These estimates
arc then summarized to show the likelihood of pesticide drift in agricul-
ture when applying pesticides in a certain manner.
The discussion of drift in agricultural pesticide applications is
examined below and is divided into three sections for convenient presen-
tation. These sections are:
1. Dust applications;
2. Granular applications; and
3. Spray applications.
The most common methods of applying the above formulations are pre-
sented in each section.
Dust applications - Dust, usually formulations of fungicides, are
primarily used on orchards with small amounts used on vegetables, orna-
mentals, etc. The use of dusts on field crops is negligible. The discus-
sion here is concerned only with the drift problems of treating trees with
pesticidal dusts.
The likelihood of drift from dust applications is very high. The
fine particle sizes have a low sedimentation rate and a low impaction ef-
ficiency which subjects them to the vagaries of shifting wind speeds and
turbulence for an extended period of time. The problem is magnified by
the fact that aircraft fly higher to dust than to spray liquids since a
heavy dose of dust ends up in the middle of the swath with the methods
commonly used.
Table 15 (p. 63) shows that particles with a size less than 50 p,
have a greater than 90% chance of drifting when released at a height of
20 ft, and an 80% chance of drifting when released at a height of 10 ft.
Even at a height of only 3 ft the chance of drift exceeds 40%. A height
of 20 ft or more is common in aircraft dusting of orchards, while an aver-
age height of 10 ft is common for dusts blown onto trees from ground rigs.
Investigations of dust drift by various researchers seem to confirm
that drift of dusts is very high. Fisher^/ reported that impaction effici-
encies of less than 8% are found with particles below 50 a. in orchards.
Splinter^./ reported that only 10 to 20% of the dust emitted in treating
crops is normally found on the crop itself. Tests conducted by Witt in
Arizona!!/ showed that at all points downwind from the target area, the
amount of dust deposited was four to 10 times higher than the amounts of
66
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spray deposited when simultaneous aircraft applications of toxaphene dust
(4 Ib/acre) and toxaphene emulsion (5 gal/acre) were conducted at wind
speeds of 3 to 4 mph, inverse conditions, and a 60°F air temperature. Table
A-2 (Appendix A) shows that dust drift amounted to 86% in a test conducted
with aircraft.
In actual practice attempts have been made to reduce dust drift by
wetting the dust as it discharges or by electrostatically charging the
dust.Jl/ These efforts have produced some positive results and did reduce
drift somewhat. Splinter£/ reported that electrostatic charging of dusts
doubled the amount of dust deposited on the crop (20 to 40%). However,
these techniques add expense to the dusting operation and are not widely
used.
The discussion on impaction efficiencies in an earlier section of
this report indicated that impaction efficiency increases with particle
speed. Airblasters use high volumes of air (as much as 100,000 cfm in
some cases) and high discharge velocities (over 100 mph in some cases).
This technique, however, does not improve impaction efficiency of parti-
cles that miss the initial target or fail to impinge shortly after dis-
charge. Wilson^./ tested an airblast sprayer that delivered 26,000 cfm at
90 mph, and found that air velocities at distances of 6, 18, 30, 42, and
54 ft were 21, 17, 14, 6, and 5 mph, respectively. Therefore, any parti-
cles that do not impact upon the target shortly after discharge slow down
rapidly and are highly subject to drift as a result.
One other point needs consideration before estimating the likelihood
of dust drift. Dusts tend to agglomerate due to their small size and elec-
trostatic forces. No matter how finely they are dispersed, some agglomera-
tion takes place, and when it does, the effective particle size of the
agglomerated dust particle is increased. This phenomenon helps to reduce
dust drift below theoretical estimates made based on particle size alone.
Two types of application methods and the associated drift are now
considered. The first method is aerial application of dusts to orchard
trees. Aircraft fly just over the trees at a height of 20 ft or more. The
dust particles can contact the trees by sedimentation from the vertical
direction or by impaction in a horizontal direction. Table 15 (p.63)
shows that dust particles, which are 50 |j, or less in size, have a 907o or
greater potential to drift over 1,000 ft from the target before sedimen-
tation occurs. Table 8 (p.51) shows that the impaction efficiency of
particles, whose size is 40 p, or less, is 40% or less (drift potential,
therefore, is 60% or greater). In addition, the turbulence caused by the
wake of the aircraft, and the wing-tip vortices, tend to lift many of the
particles up higher than the height at which they are released. These
facts and the studies previously mentioned indicate that dust drift can
67
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be as high as 90% from aircraft. On the other hand, particle agglomera-
tion and filtration of the airborne dust particles by many trees through-
out the orchard (even with the low impaction efficiency) can reduce this
amount somewhat. The studies previously mentioned indicated that between
70 and 90% losses were observed. Taking all of this into consideration,
the estimated drift loss from aerial application of dusts in orchards is
between 70 and 90%.
The other method considered is airblasting the dust onto the trees
from a ground rig. Both hand-guns and nozzles mounted on the airblast
unit are used. Two advantages this method has over aircraft application
is that many particles do not get to the height at which aircraft fly and
more control over the placement of the particles is obtained (aircraft
blanket an orchard while ground rigs can treat individual trees). How-
ever, to maintain complete coverage ground airblasters have to aim at
the tops of the trees and blow particles upward. Many of the particles
become airborne in this manner. As was mentioned previously, particles
which do not impact immediately lose their initial velocity and the im-
paction efficiency of these particles rapidly falls. Considering all of
these facts, the amount of drift associated with orchard airblasters is
less than that of aircraft, but not a great deal. The estimated drift
loss from ground rig airblasters, then, is 60 to 80%.
Granular applications - The likelihood of drift from granular ap-
plications appears to present no drift problems since the granules most
commonly used are sized to be 250 p, or greater. The screening operation,
however, does not entirely eliminate the small particles (10% may be
larger or smaller than the designated size when the NACA Granular Pesti-
cide Committee guidelines are followed). Once the granules are packaged
in bags they are subject to breakage and crushing during handling and
transportation. Finally, the granules are subject to further size reduc-
tion when passing through the mechanical dispersal process of the pesti-
cide applicator.
A study by Meyers and Lovely (1957)i£' conducted on an attapulgite
RVM 30/60 granular determined that 5.5% of the material passed through
a 60 mesh screen prior to being subjected to passage through an appli-
cator. The weight of particles below 60 mesh (250 p,) after the granules
were passed through a variety of metering devices found on applicators
ranged from 6.0 to 9.1%. Thus, the weight of particles below the stated
minimum size is presumably 5 to 97o of the total weight of granules ap-
plied.
No statistics were available on the particle size distribution of
the particles below 250 p, that were measured in the above study. On a
weight basis the percentage below 50 |j, (dust) is quite insignificant,
and is assumed to be about 107o of the subsized particles. The 50 to
68
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100 ^ range is assumed to be about 20% of the total weight, leaving the
remaining 70% in the 100 to 250 p, range. Only the particles below 100 p,
have a significant drift potential, as shown in Table 15 (p.63).
Using the above assumptions gives the result that about 1% (10% times
5 to 9%) of the total weight of the granules is in the sub-50 JJL range,
and about 1.5% (20% times 5 to 9%) of the total weight of the granules
is in the 50 to 100 |j, particle range. Since most of the herbicides and
insecticides applied above the soil are either 25/50 or 30/60 mesh, then
all aerial applications, boom-type applications, and centrifugal applica-
tions are subject to some drift.
Table 15 (p.63) shows the potential for drift at various release
heights in 3 to 5 mph winds. Combining the values in Table 15 and the
above information gives the following estimates for drift from granular
applications (Table 18):
Table 18. ESTIMATED DRIFT POTENTIAL OF GRANULAR
PESTICIDE APPLICATIONS
Average drift potential
Application and Release for a particle whose
method of height size is; Likelihood of drift
application (ft) < 50 u 50 to 100 u, beyond 1.000 ft
Aircraft,
broadcast 10 90% 30% 1.5%
Boom,
broadcast 3 70% 10% 1%
Boom, band 1/2 30% 0% < 0.5%
Centrifugal,
broadcast 3 70% 10% 1%
Planter, band 1/2 30% 0% < 0.5%
Note: The drift potential for each size range is multiplied by the weight
of particles in that range (1 and 1.5%, respectively) to deter-
mine the percent drift.
69
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Spray applications - Spray applications vary widely in formulations,
methods of application, and application equipment used. For a discussion
of drift it is most convenient to separate the spray operations into ground
and aerial equipment applications. These two sectors can then be subdivided
as required to cover the many facets of operation involved in each sector.
The following discussion addresses ground equipment and aerial equipment
separately.
Ground equipment - In addition to the information given earlier on
formulations, methods of application, nozzles, volume of spray per acre,
and application heights used in ground equipment pesticide application
operations, it is also necessary to know the droplet size VMD's and the
droplet size spectrums involved in spray applications to determine the
drift potential of various spray operations. This subject and the like-
lihood of drift is discussed below for both field crop and orchard spray-
ing by ground equipment.
Field crops - The likelihood of drift from ground spraying opera-
tions in field crops can be determined from Table 16 (p.63) and the drop-
let size VMD and droplet size spectrum for water emulsions and wettable
powder formulations given in Tables 12 and 13 on the preceding pages. The
typical operating parameters used in field crops and the associated drop-
let size VMD and droplet spectrum are given in Table 19 on the following
page. Table 16 shows that particles greater than 100 |j, released from a
height of from 6 in. to 1.5.ft have a negligible chance of becoming drift.
Those released at a 3 ft height have a very small chance of drifting in
the 100 to 120 y, range. These statistics show that the chance of drift
to 1,000 ft or more from the operations listed in Table 19 is negligible
with the exception of booms applying sprays to the plants.
Foliar application operations using cone nozzles operate anywhere
from 3 to 7 ft above the ground, and produce finer sprays than the soil
application equipment. The table above shows that with ULV spraying the
droplets produced below 100 \i can vary from 2 to 15% by volume, and LV
spraying produces droplets below 100 u, at the rate of about 1% by volume.
At a height of 3 to 7 ft, most of the water in these droplets will evapo-
rate to dryness before reaching the ground if they do not impinge upon
the plant. Therefore, the opportunity for drift exists under these cir-
cumstances and cannot be considered negligible.
The degree to which drift occurs depends upon the number of droplets
that do not contact the plant and, are, therefore, airborne between the
nozzle and the ground. This is difficult to determine, and no information
was available on the subject under actual field conditions. Since small
particles have a low impaction efficiency, it is assumed that most of the
70
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Table 19.
TYPICAL OPERATING PARAMETERS, DROPLET SIZE VMD'S, AND DROPLET SIZE SPECTRUMS
ENCOUNTERED IN FIELD CROP SPRAY APPLICATIONS
Application method
Boom, broadcast
Boom, broadcast
Boom, broadcast
Boom, band
Boom, band
Boom, foliar
Boom, foliar
Boomless, broadcast
Nozzle
type
Fan spray
Fan spray
Flooding
Fan spray
Fan spray
Cone spray
Cone spray
Flat spray
Pressure
(psi)
20-40
20-40
10-40
20-40
20-40
40-80
40-80
10-40
Volume
ULV
LV
LV
ULV
LV
ULV
LV
LV
Drop VMD
300-400
350-600
»/
300-400
350-600
150-250
250-400
y
Drop spectrum
Volume 7» less than
specified size
0 < 100 u
0 < 100 u
0 < 100 u
0 < 100 11
0 < 100 u
2 to 15 < 100 u
1 < 100 u
0 < 100 vi
aj No information available on flooding nozzles but they are used to produce coarse droplet VMD's,
500 u or greater, and have negligible volume of droplets less than 100 u.
b/ No information available, but are similar to fan spray nozzles except that the output per nozzle
is much higher (about 10 times higher) at the same operating pressures. This means that drop-
let size VMD is higher than for fan spray broadcast, and is not a drift problem.
-------
particles below 100 p, do not contact the plant and become airborne. Table
16 (p.63) shows that these small particles have about a 70% chance of
drifting over 1,000 ft. This is particularly true of wettable powder form-
ulations, which have small particle sizes (most < 20 jj,), since complete
evaporation takes place before sedimentation of the droplet on the ground,
and only the wettable powder particle remains after evaporation takes
place.
Assuming an average value of about 10% by volume for droplets less
than 100 p, in ULV operations, this means that about 7% (70% times 10%)
of the spray volume drifts to a distance of over 1,000 ft. For LV opera-
tions only about 1% by volume is subjected to drift and the 1% figure is
taken as the volume that drifts over 1,000 ft.
To further substantiate the findings above, Table 20l-t' gives the
calculated deposit rates of various drop size VMD's to a distance of 1,000
ft when sprays are applied by ground equipment from a 3-ft height above
the ground.
Table 20 shows that a 100 p, drop VMD will have only 20% drift beyond
1,000 ft, and all of the operations discussed in this section have drop
VMD's above 300 y, with the exception of the foliar application. If the
percentage of droplets under 100 \i have a VMD of, say 50 p,, then the cal-
culations above show that 627o of these particles drift. The assumption
of 70% drift for the small particles does not seem unreasonable, consid-
ering the fact that a small fraction of the particles above 100 \i will
drift also.
The likelihood of drift of the operations in this section are given
in Table 21.
72
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Table 20. CALCULATED DEPOSIT RATES (%) OF VARIOUS DROP SIZE RANGES
APPLIED BY GROUND EQUIPMENT UNDER CONDITIONS OF NEUTRAL OR
SMALL TEMPERATURE GRADIENT IN 3 TO 5 MPH WINDS
Drop size
range Percentage deposit (cumulative) downwind**/
(VMD. urn) 49 ft 98 ft 327 ft 457 ft 984 ft
10 0 1 3 3.3 3.5
25 1.0 1.5 5 10 13
50 10 25 30 35 38
100 25 50 70 75 80
£/ Dispersal of pesticide made at 3 ft above the ground.
Source: Akesson, N. B., and Yates, W. E., "Physical Parameters Relating
to Pesticide Application," personal communication.
Table 21. THE LIKELIHOOD OF DRIFT IN GROUND
EQUIPMENT SPRAY APPLICATIONS
Operation Likelihood of drift
Boom, broadcast < 1%
Boom, band < 1%
Boomless, broadcast < 17o
Boom, foliar, ULV 7%
Boom, foliar, LV 1%
73
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Orchards - The likelihood of drift varies substantially with the
type of applicator used. Drift from herbicide applications to the soil
is negligible since flooding nozzles and flat fan nozzles are commonly
used in conjunction with dilute sprays and keep drift at a very minimum.
If this practice is not followed, severe damage to the trees results
from contact with the herbicides commonly used. Drift from high volume
spraying of the trees with spray guns, and low volume and ultra low
volume spraying with air blasters is not negligible.
High-volume, high-pressure spraying is normally done at pressures
of about 600 psi.—' The spray is directed up, over, and at the tree to
insure complete spray runoff. No information was found on the droplet
VMD's normally used in this operation, but they are assumed to be about
300 to 500 u. VMD at the pressure and spray volumes used. The spectrum of
droplets, however, is much wider than at lower pressures.
Since information on this operation was not obtained, an estimate
must be made. Table 12 (p-56) shows that a D10-25 hollow cone nozzle
operating at 50 psi produces a drop VMD of 410, and 0.5% of the volume
of droplets formed are less than 100 p,. A D10-45 hollow cone nozzle
operating at 50 psi produces a drop VMD of 470 p,, and 1.0% of the
volume of droplets formed are less than 120 u,. Since spray guns use
nozzles similar to hollow cones and operate at very high pressures,
the assumption is made that about 5% of the drops formed are less than
100 u. in size.
Table 16 (p.63) shows that at a release height of 10 ft, about
80% of the drops below 100 u. drift. The height of 10 ft is used as an
average height since the spray is directed up to treat the tree. Table
16 also shows that 200 u, particles have a 15% drift potential. Taking
into account the filtration of drifting particles by trees throughout
the orchard, and assuming that the filtration effect reduces the drift
by an amount equal to the drift experienced by particles above 100 u.,
we have an estimated drift of 80% of the sub-100 |j, particles (5% of the
total volume), or a total estimated drift of 4% of the amount applied.
Orchard airblasters are commonly used for spray applications to trees
today. They are also the largest source of drift in sprays applied from
ground equipment. A search of the literature has shown that airblast spray-
ers are comparable to aircraft in quantities of drift emitted.22t23/
74
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The use of airblast sprayers has increased since they can spray con-
centrations of pesticides that are 6X or higher and achieve good coverage.
At a 6X concentration, about 50 gal. of solution per acre is required,
which is considered low volume..iz/ Most conventional units are capable
of applying spray mixtures up to 6X concentration, and some newer machines
with special metering pumps can deliver mixtures as great as 33X concen-
tration. The recommended application procedure is to apply two-thirds of
the spray to the top one-third of the tree, and the remaining one-third
to the lower two-thirds of the tree. Extensive research has shown this
procedure is required to get uniform coverage of the entire tree.£/
Airblasters use stationary nozzles mounted on the unit, normally in
a semicircular arrangement directed up towards the foliage to dispense
the spray. When applying concentrate solutions (such as 33X) the spray
is applied at the rate of about 10 gal/acre or less, which is considered
ultra low volume. The droplet VMD is in the aerosol range of about 50 to
100 n for this operation (sometimes called mist blowing). When spraying
the more conventional concentration of 6X, the droplet VMD is about 150
to 250 p, and is considered low volume (about 50 gal/acre). The fact that
airblasters use high volumes of air (60,000 to over 100,000 cfm) and proj-
ect the droplets at high speeds of 80 mph or greater makes the drift hazard
great.
The drift hazard in orchards is high since the tree tops can be 20
to 30 ft from the sprayer when the tree spacings are 30 to 40 ft. Even
with an airflow of 50,000 cfm, the time required for impingement of the
small droplets on the tree from the time of discharge can be 1 to 5 sec.
This allows time for the droplets to both slow down and undergo evapora-
tion.—' Since two-thirds of the spray is directed towards the treetop,
most of the droplets will reach a height of 20 ft or greater.
As previously mentioned in the discussion on dusts, the velocity of
the droplets slows down considerably as the distance of travel from the
airblaster increases. By the time the droplets reach the tree they are
traveling at a speed of about 20 mph or less when the distance is 30 to
40 ft. Table 8 (p.51) shows that the impaction efficiency of particles
whose size is 40 p or less is under 40% at 3 to 5 mph, and that 100 (j,
particles have impaction efficiencies of about 80%. If the particles do
not impinge on the target tree, they undergo further speed reductions
down to the wind speed of the atmospheric air, and have very low impaction
efficiencies at this point.
75
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To further add to the problem of drift is the fact that when low volume
sprays (and volatile ultra low volume concentrates) are applied, evapora-
tion reduces the particle size formed at emission to a smaller size yet.
Figure 8 (p.51) shows that in a distance of 15 ft, all water droplets of
150 (j, or less evaporate to dryness. This means that by the time the pesticide
particle reaches the tree it is a dust (in the case of wettable powders)
or the liquid pesticide concentrate itself, since all the dilution water
has evaporated. This fact combined with the others mentioned above indi-
cates that the drift potential for airblast spray applications is indeed
high.
A study given in Appendix A conducted by Ware et al., compared the
drift from a mist-blower to that of an airplane application. They found
that the mist-blower spray, with a droplet VMD of 100 p, in the target
area, produced greater amounts of drift at all distances up to 1/2 mile
than did the airplane spray. The conclusions were that the high initial
velocity (90 mph) and smaller droplet size (100 versus 140 p,) of the mist-
blower contributed to this fact.
To estimate the drift potential of airblasters is difficult since
the amount of initial impingement of sprayed drops on the target tree is
unknown. Table 9 (p.53) shows that the droplet VMD size range of 50 to
100 p, (coarse aerosols), typical for ULV airblast applications, produces
60% of the drops by volume in sizes less than 100 p,. In the 100 to 250 p,
VMD range, typical for LV airblast operations, only 167<> of the drops by
volume have sizes less than 100 p,. Assuming that flash evaporation occurs
with LV particles and that by the time they reach the tree they are under
40 p, in size, the impaction efficiency of these drops is about 20%. Table
16 (p.63) shows that at heights of 3 ft or more, 40 p, particles have
greater than a 95% chance of drifting over 1,000 ft.
Combining all of these statistics gives Table 22.
Table 22. LIKELIHOOD OF DRIFT FROM AIRBLASTERS
Impaction
% Particles efficiency Percent particles Likelihood of
Operation below 40 q. (%) airborne drift (%)
Airblast,
ULV 60 20 48 45
Airblast,
LV 16 20 13 12
76
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These figures take into account only the particles emitted from the
airblaster that are 100 p, or less at the time of emission. The ULV opera-
tion emits all of the particles at a size below 180 p, (Table 9, p.53),
and many of the 100 to 180 p, particles will drift also. If the impaction
efficiency of 20% is used with all of the ULV droplets (100%), then the
drift potential increases to 75% (95% times 80%). In the same manner about
50% of the LV droplets by volume are 150 p, or less (Table 9). If the im-
paction efficiency of 20% is used with all these droplets (which will
evaporate in the 15 ft distance), then the drift potential increases to
45% (95% times 50%).
Considering all of the statistics presented above, and the filtration
effect of all the trees in the orchard (at collection efficiencies below
10%), the estimates for the likelihood of drift beyond 1S000 ft in orchards
when spraying with airblasters is: (a) ULV airblasting, 40 to 70%; and
(b) LV airblasting, 10 to 40%.
Aerial equipment - In addition to the information given earlier on
formulations, methods of applications nozzles, volume of spray per acre,
and application heights used in aerial equipment pesticide application
operations, it is also helpful to know the droplet size VMD's and droplet
size spectrums commonly used in agriculture. The droplet size VMD and the
droplet size spectrum for water emulsions and wettable powder formulations
are given in Tables 12 and 13 on the preceding pages. The pressure of 50
psi in those tables is high (40 psi normal), but was the only information
available,, These tables show that ULV applications have droplet VMD's be-
tween 200 and 250 p,, and the percentage of drops below 120 p, is 10% by
volume. The LV applications have droplet size VMD's of 250 to 500 p,, and
the percentage of drops below 120 p, are 570 by volume. However, the deter-
mination of drift from aerial equipment applications must be made with
a different approach than that used with ground equipment since aerial
applications differ markedly from the other types of equipment previously
discussedo The basic concepts and parameters discussed previously do not
completely predict the drift from aircraft for two reasons; (a) the ef-
fect of the speed of the airplane; and (b) the turbulence created by the
aircraft itself. To better understand how drift from aircraft occurs, a
look at what is involved is helpful,,
First, the drift from airplanes and helicopters is not a great deal
different, since helicopters flying at 15 mph or greater have similar
turbulent conditions to airplanes.^:' Only when they fly below this speed,
or hover, does the effect of the downdraft become significant. Since most
helicopters fly at speeds of 40 to 60 mph when applying pesticides, the
two types of aircraft have similar circulation patterns. (Helicopters
77
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normally do not spray pesticides when hovering due to the high risk of
contaminating the helicopter itself.) Figures 9 and 10.12.' show the vortex
and circulation patterns of both a fixed wing monoplane and a helicopter.
Notice that the patterns are similar when the speed of the airplane is
80 mph and the helicopter speed is 15 mph. Therefore, helicopters and
fixed-wing aircraft are considered to have similar drift potentials and
are both hereafter designated as aircraft.
The effect turbulence created by the aircraft has on droplet dis-
persal is complex. The air currents that aircraft create cause an upward
motion of the air at the wing tips and a downwash under the aircraft.
(Fixed-wing aircraft also have a propeller wake with a rotational compo-
nent.) As a result of these air currents small particles can be projected
up 15 to 20 ft in the air after being released from a boom less than 10
ft off the ground. Tests with helicopters showed that the wing tip vor-
tices are reduced at higher forward speeds. A comprehensive study by Reed
showed that drops as large as 210 |j, were given a looping trajectory by
the wing tip vortices.—'
The complexity of the above factors shows that no simple estimate
can be made on drift without field test data. The nine field studies pre-
sented in Appendix A are given to support and document the estimates made
here on drift from aerial spray operations. A brief examination of these
studies is given here, and then the estimates are made based on the data
presented.
ULV applications;
1. Study (1), Table A-l, shows that pesticide applications in the
100 to 300 to, VMD range are subject to drift to 1,000 ft in 3 to 5 mph winds
when released by aircraft. The amount of drift varies from 20 to 60% of
the volume applied.
2. Study (3), Table A-4, shows that ULV spray applications (1/2 pt
to 1/2 gal/acre) by aircraft are deposited on-target in the range of 5
to_5p%^ depending on release height and air wind speeds. At low wind
speeds of 2 mph, only 50% of the spray drifted out of the target area,
whereas in 10 mph winds, the drift ranged from 70 to 90%. By comparison,
diluted sprays (1 to 1-1/2 gal/acre) drifted more than ULV sprays.
3, Study (4), Table A-5, points out the fact that ULV aerial appli-
cations, applied at a height of 5 ft and at an aircraft speed of 80 mph,
drifted 1,000 ft or more downwind from the target. The amounts of drift
to this distance were 48 to 60% of the amount applied.
78
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FAIRCHILD - MODEL 24
BOOM LOW
80 MPH - LOW FLIGHT
Figure 9. Vortex patterns in the wake of
a passing high-wing monoplane.
BELL HELICOPTER
15 MPH - HIGH FLIGHT
Figure 10. Vortex patterns in the wake of a helicopter.
79
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4. Study (5), Table A-6, shows that applications of undiluted pesti-
cide (about 1 pt to 1/2 gal/acre) averaged 62% drift beyond a 3/8 mile
distance downwind in four tests. At an application height of 8 ft, 82%
of the azinphosraethyl (1 pt/acre) drifted beyond 1/2 mile, while at a 30-
ft application height, only 38% drifted downwind. The malathion (1/2 gal/
acre) drifted about the same at both 8 and 30 ft heights of application.
The percent drift beyond 3/8 mile for each height was 69 and 61%, respec-
tively.
These studies indicate that the range of drift for ULV applications
is quite wide. A summary of these studies shows that:
Study Drift beyond 1,000 ft (%) Wind speed (mph)
(1) . 20-60 3-5
(3) 50, 70-90 2, 10
(4) 48-60 Not given
(5) 38-82 Not given
Study (1) includes VMD's up to 300 p, which are too high for most ULV spray-
ing, so the low percentage is too low. Study (3) shows drift to only 100
ft, not 1,000 ft, so these figures are high for drift to 1,000 ft. The
average value for drift in Study (5) was 62%.
Taking all these facts into account places the estimated range of
drift for ULV applications at moderate (3 to 5 mph) wind speeds between
40 and 60%.
LV applications;
1. Study (1), Table A-l, indicates that aerial applications of sprays
with a droplet VMD of 300 to 400 |j, are subject to drift beyond 1,000 ft
in 3 to 5 mph winds. The amount of drift varies from 10 to 30%.
2. Study (l)a, Table A-2, also shows that for a large number of tests
the average percent drift out of the target area was about 4770 for LV ap-
plications.
3. Study (4), Table A-5, shows that 55% of a 2 gal/acre spray formula
drifted over 1,000 ft from the target. Only one test was performed.
80
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4. Study (5), Table A-6, indicated that drift from a diluted spray
formulation ranged from 4 to 54% drift beyond a distance of 3/8 mile down-
wind. The average drift was 29% for the four tests conducted.
5. Study (7) showed that the drift from a LV aerial application was
about five times greater than for a high clearance ground sprayer. (Note:
This study previously determined that the drift range for the ground rig
is about 7%, making drift from the aerial application about 357o») These
studies indicate that the range of drift for LV applications is quite wide.
A summary of these studies shows that:
Drift beyond 1,000 ft (%) Wind speed (mph)
10-30 3-5
47 Various speeds
55 Not given
4-54 Not given
35 1-2
Study (l)a gives drift from the target area only and is too high for drift
to 1,000 ft. The average drift for Study (5) was 29%.
Taking all the above facts into account places the estimated range
at 10 to 40% drift, primarily since Study (1) was developed over a long
period of time and the other studies do not disagree to any extent.
The next section summarizes the findings of this section and puts
them all into one table.
Drift From Agricultural Pesticide Applications - Quantities - This sec-
tion has one purpose, and that is to bring all of the estimates on drift
that were made in the previous section into one place, Table 23. This table
lists all of the types of equipment considered in the previous section;
the method of pesticide application used by each equipment typej the tar-
get; and the volume of spray application. With each type of operation shown
in Table 23, the estimated percent drift to 1,000 ft from the target is
given. The meteorological conditions assumed with these estimates are 3
to 5 mph wind speeds, neutral atmospheric stability, warm temperatures,
and a relative humidity of 50% or less.
81
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Table 23. LIKELIHOOD OF PESTICIDE DRIFT DURING CROP TREATMENT IN AGRICULTURE
BY METHOD OF APPLICATION
00
NS
Formulation Equipment type
Dust Aircraft, venturi
Airblaster
Spray Tractor, boom
sprayer
Tractor, boomless
sprayer
Spray gun
Orchard airblaster
Aircraft, boom
sprayer
Granular Aircraft, venturi
Spreader, centri-
fugal
Spreader, boom
Planter
Pesticide
application method^'
Air, foliar
Ground, foliar
Ground, foliar
Ground, foliar
Ground, broadcast
Ground, broadcast
Ground, band
Ground, band
Ground, broadcast
Ground, broadcast
Ground, foliar
Ground, foliar
Ground, foliar
Air, foliar
Air, foliar
Air, foliar
Air, foliar
Air, broadcast
Air, broadcast
Ground, broadcast
Ground, broadcast
Ground, band
Ground, band
Estimated percent
Spray drift over 1,000 ft
Target application volume^' from targe t£'
Trees
Trees
Plants
Plants
Soil
Soil
Soil
Soil
Soil
Soil
Trees
Trees
Trees
Trees
Trees
Plants
Plants
Soil
Soil
Soil
Soil
Soil
Soil
-
ULV
LV
LV
HV
ULV
LV
LV
HV
HV
ULV
LV
ULV
LV
ULV
LV
LV
_
-
-
-
—
70-90
60-80
5-10
1
Negligible
Negligible
Negligible
Negligible
Negligible
Negligible
3-5
40-70
10-40
40-60
10-40
40-60
10-40
10-40
1-2
1
1
Negligible
Negligible
a/ Air refers to pesticide application by aircraft, ground refers to pesticide application by ground rigs.
W HV = High Volume; LV = Low Volume; ULV = Ultra-Low Volume.
£/ Assumes a 3 to 5 mph wind; neutral atmospheric stability (S.R. = 0), air temperatures above 60°F; and
a relative humidity of 50% or less.
-------
The estimates for sprays given in Table 23 will change if the meteoro-
logical conditions change. The meteorological conditions given do not af-
fect solid particles with the exception of wind speed. However, the esti-
mates given in the table are generally good for winds below 10 mph, and
pesticide applications made in winds greater than 10 mph are not recom-
mended at all. To show how the relative magnitude of the estimates on
spray drift change with different meteorological conditions, the following
facts are given:
1. If wind speeds increase, drift increases.
2. If temperature increases, drift increases.
3. If relative humidity increases, drift decreases.
4. If the stability ratio increases (becomes positive), the drift
decreases.
Table 23, then, represents the estimates for the amount of pesticide
lost due to drift when treating crops in the manner indicated in the table.
To estimate the actual losses of pesticides in agriculture due to drift
during application requires the knowledge of: (a) the quantities of pesti-
cides applied; (b) the manner in which they are applied; (c) the formulations
used; and (d) the size of the crop being treated. With this information and
Table 23, estimates can then be made as to the amount of pesticide that
drifts away from the crop during application.
The next section makes estimates on the pesticide drift losses from
the U.S. corn, sorghum, and apple crops for the year 1971 after the neces-
sary information is given.
Estimated Pesticide Losses Due to Drift From the U.S. Corn, Sorghum,
and Apple Crops (1971)
This section estimates the pesticide drift losses experienced in 1971
during treatment of the U.S. corn, sorghum, and apple crops. In order to
do this, three basic parameters that directly affect pesticide loss due
to drift are quantified for each crop and for each category of pesticide
examined. The three parameters are:
1. Quantity of pesticide applied;
2. Pesticide formulations used; and
3. Method of application.
83
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Once these parameters are quantified, the amount of pesticide drift
that occurs during crop treatment is estimated by using the values given
in Table 23 for the likelihood of drift which accompanies each method of
application.
Notice that the fourth parameter (size of the crop being treated)
mentioned in the previous section is not included. This parameter is
important since Table 23 only estimates the percentage of drift to 1,000
ft. However, the inclusion of this parameter involves a great deal of
calculating and estimating since each individual farm (or groups of farms
the same size) within the three study crops would have to be considered
separately. (In other words, percentage drift from a small farm is greater
than from a large farm since 1,000 ft from the target on a large farm is
more often within the borders of the farm.) This parameter, therefore,
is not considered in these estimates.
In practice, for one reason: the size of the farm does not make a
great deal of difference. The amount of pesticide which drifts to 1,000
ft is dispersed in small particles, most of which are capable of drifting
for miles. Only small amounts of the drift cloud will settle to the soil
with incremental distances. This means that the difference between the
amount of drift from a 100-acre farm and a 1,000-acre farm is about 10%
of the total drift at 1,000 ft, and is not considered significant in the
estimations in this section. (See Table 20, p.73, for the effect of
distance on decreasing percentages of drift settlement to the ground.)
Another parameter held constant in the estimations in this section
is the meteorological conditions. The percentages of drift in Table 23
are based upon the meteorological conditions given at the bottom of the
table. Since these conditions are typical of actual field conditions,
the assumption is made that the average or typical climatic conditions
under which pesticide applications were made in 1971 are those given in
Table 23.
Each crop is discussed in a separate section below. The pesticides
lost due to drift from each crop are divided into four separate categories
which are: (a) herbicides; (b). insecticides; (c) fungicides; and (d) other
pesticides.
Estimated Pesticide Drift Losses from the U.S. Corn Crop (1971) - The pes-
ticide losses due to drift during application from the 1971 corn crop are
estimated in three separate parts: (a) herbicides and insecticides; (b)
fungicides; and (c) other pesticides.
84
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Herbicides and insecticides - The quantities of herbicides and in-
secticides applied to the corn crop (1971) are given in Appendix C,
Table C-l. Herbicides accounted for 101,060,000 Ib of pesticides used
on corn, and insecticides accounted for 25,531,000 Ib of pesticides used
on corn.
The formulations for herbicides were primarily wettable powders and
emulsions, with a small usage of granules and no dusts. Since no informa-
tion is available on the exact amounts of spray formulations and granules
used that year, the following assumptions are made, based on the method
of application:
Ground application equipment - 107o granules, 90% spray.
Aerial application equipment - 30% granules, 70% spray.
The formulations for insecticides were primarily granules, with a
small usage of spray and no dusts. Since no information was available on
the exact amounts of spray formulations and granules used that year, the
following assumptions are made, based on method of application:
Ground application equipment - 90% granular, 10% spray.
Aerial application equipment - 50% granular, 50% spray.
The method of application of insecticides and herbicides was docu-
mented in 1971. Corn farmers in the United States apply most of the pes-
ticides to the crops rather than contracting the work to commercial
applicators. The five state survey conducted in the Lake States Region=_t'
provides detailed information on this subject. Table 24 shows the amount
of corn acreage treated by the farmers themselves and by custom appli-
cators in the states of Michigan, Wisconsin, Minnesota, and Illinois,
and these statistics are summarized below:
Time of Acres treated Acres (OOP) treated by:
Pesticide application 1971 (OOP) Self _%_ Custom %
Herbicides Preemergence 14,553 11,985 82.4 2,568 17.6
Postemergence 9,219 7,058 76.6 2,161 23.4
Subtotal 23,772 19,043 80.1 4,729 19.9
Insecticides Preemergence 8,257 7,941 96.2 316 3.8
Postemergence 437 320 73.2 117 26.8
Subtotal 8,694 8,261 95.0 433 5.0
Total 32,466 27,304 84.1 5S162 15.9
85
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Table 24. PESTICIDE APPLICATION TO CORN, BY APPLICATOR, 1971-/
Percent of acres treated by:
State
Michigan
Wisconsin
Minnesota
Illinois
Pesticide
Herbicides:
Preemergence
Postemergence
Insecticides:
Preemergence
Postemergence
Herbicides:
Preemergence
Postemergence
Insecticides:
Preemergence
Postemergence
Herbicides:
Preemergence
Postemergence
Insecticides:
Preemergence
Postemergence
Herbicides:
Preemergence
Postemergence
Insecticides:
Preemergence
Postemergence
Self
86
89
98
22
72
67
93
59
90
72
98
45
81
81
96
96
Custom operator
14
11
2
78
28
33
7
41
10
28
2
55
19
19
4
4
Acres (000)
treated 1971
1,252
975
271
3
1,815
1,065
835
75
3,308
3,764
1,663
136
8,178
3,415
5,488
223
Acres treated by (000):
Self
1,077
868
266
1
1,307
714
777
44
2,977
2,710
1,630
61
6,624
2,766
5,268
214
Custom
175
107
5
2
508
351
58
31
331
1,054
33
75
1,554
649
220
9
Total
32,466
27,304
a/ Statistics from the following sources:
General Farm Use of Pesticides, 1971, Wisconsin Department of Agriculture.
General Farm Use of Pesticides, 1969-1971, Michigan Department of Agriculture.
General Farm Use of Pesticides, 1972, Minnesota Department of Agriculture.
Illinois Pesticide Use by Illinois Farmers, 1972, Illinois Department of Agriculture.
5,162
86
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These four states harvested 22,161,000 acres of corn in 1971, or
30.470 of the total U.S. corn crop* From the above summary it is evident
that about 80% of all herbicides were self-applied, and 95% of all in-
secticides were self-applied.
These figures are taken to be typical of the entire U.S. corn crop.
Two other sources of information also confirm this assumption. Indiana
reportedzi' that in 1970 all herbicides applied to field crops (corn,
soybeans, oats, wheat, barley, rye and hay) were self-applied on 86% of
the acres treated and insecticides were self-applied on 95% of the acres
treated. South Dakota reported in 1973 that 90% of the herbicides ap-
plied to corn and sorghum were self-applied, while 85% of insecticides
were selfapplied. These two states harvested 9,350,000 acres of corn
in 1971, or 12.8% of the total U.S. corn crop. All six states given here
harvested 43% of the entire corn crop in 1971.
Since the above statistics represent the self-application versus
custom application techniques used on almost half of the entire U.S. corn
crop, they are treated as typical for the entire crop. Statistics sum-
marizing the pesticide usage by applicator for the U.S. corn crop in 1971
are:
Time of Acres treated Acres (OOP) treated by;
Pesticide application 1971 (OOP) Self % Custom %
Herbicides Preemergence 46,900 38,500 82 8,400 18
Postemergence 29,800 22,900 J77 6,900 23
Subtotal 76,700 61,400 80 15,300 20
Insecticides Preemergence 26,600 25,500 96 1,100 4
Postemergence 1,400 1,000 73 400 27^
Subtotal 28,000 26,500 95 1,500 5
Total 104,700 87,900 84 16,800 16
87
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The method of application of the pesticides to the crops is also given
in detail in the five-state survey. Farmers reported whether the pesticide
applied, either self or custom, was a broadcast or band application. The
broadcast application was further characterized as surface applied or in-
corporated into the soil. The results of the 1971 survey are given in Table
25.
The percentages in the table are based on the percentages of reports
collected during the survey, not the acreage involved. This makes the sta-
tistics somewhat unreliable, but some general conclusions may be drawn.
These interpretations are summarized below as being typical overall values
for the entire U.S. corn crop:
% Acres treated
Broadcast
Incorporated
Pesticide Time of application Surface applied in soil Band
Herbicide
Insecticide
Preemergence
Postemergence
Preemergence
Postemergence
50-80
60-90
5-10
50-80
5-15
2-10
10-20
5-15
10-30
5-30
70-90
20-40
Though these statistics are crude, they do show that most herbicides
are broadcast, while most of them are surface applied rather than incor-
porated into the soil. Most preemergent insecticides are band applied while
postemergent insecticides are broadcast. The percentages can vary widely
with formulation, type of pesticide used, and geographical location so
that no exact figures can be readily obtained.
The quantity of herbicide drift is estimated from the above assump-
tions, the statistics provided by the five state survey, and the values
for percent drift given in Table 23 (p.82). In order to do this, the
quantities of herbicides applied to the crop must be determined by for-
mulation, by method of application, and by type of application equipment.
The assumption is made, therefore, that the herbicides were distributed
equally on the acres treated, since the statistics developed under the
methods of application apply to acres treated, not pounds applied.
88
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Table 25. PESTICIDE APPLICATION TO CORN, BY METHOD, 197Li/
Method of application, broadcast^.'
State
Michigan
Wisconsin
Minnesota
Illinois
Pesticide
Herbicides:
Preemergence
Postemergence
Insecticides:
Preemergence
Postemergence
Herbicides:
Preemergence
Postemergence
Insecticides :
Preemergence
Postemergence
Herbicides :
Preemergence
Postemergence
Insecticides :
Preemergence
Postemergence
Herbicides:
Preemergence
Postemergence
Insecticides:
Preemergence
Postemergence
Surface applied
82
92
10
100
89
94
21
61
32
84
7
73
49.5
6
14
Incorp. in soil
5
1
16
0
6
1
11
10
4
0
6
7
16.0
24
16
Band
13
7
74
0
5
5
68
29
64
16
87
20
34.5
70
70
aj Statistics from the following sources:
General Farm Use of Pesticides, 1971, Wisconsin Department of Agri-
culture.
General Farm Use of Pesticides, 1969-1971, Michigan Department of
Agriculture.
General Farm Use of Pesticides, 1972, Minnesota Department of Agri-
culture.
Illinois Pesticide Use by Illinois Farmers, 1972, Illinois Depart-
ment of Agriculture.
b_/ Percent of reports.
89
-------
The amount of herbicides applied to the 1971 corn crop was 101,060,000
Ib. Preeraergent applications were 61% of the total, or 61,600,000 Ib, and
postemergent applications were 39% of the total, or 39,400,000 Ib. Pre-
emergent applications are divided into three methods: (a) soil surface
broadcast, 70%; (b) soil incorporated broadcast, 10%; and (c) band, 20%.
Postemergent applications were also divided into three methods of
application: (a) soil surface broadcast, 75%; (b) soil incorporated
broadcast, 5%; and (c) band, 20%.
The applicators for the preemergent herbicides were: (a) self, 82%;
and (b) custom, 18%; and for the postemergent herbicides were: (a) self,
77%; and (b) custom, 23%.
These statistics give the following information:
Broadcast Surface
applications incorporated Band applications
Time of application (OOP Ib) (OOP Ib) (OOP Ib)
Preemergent 43,100 6,200 12,300
Postemergent 29,500 2,000 7,900
All applications made by the farmer himslf are assumed to be ground
equipment applications. This leaves 18% of the preemergent herbicides avail-
able for aerial application by custom applicators and about half (or 10%
of the total preemergent applications) of custom applications are assumed
to have been made aerially. Likewise, only 23% of the postemergent herbi-
cides were applied by custom applicators, and about half (or 10% of the
total postemergent applications) of these applications are assumed to have
been made aerially. All aerial applications are surface broadcast applica-
tions since banding or soil incorporating herbicides with aircraft is
impossible.
Table 26 is constructed with the previous assumptions made on formula-
tions used and the values given in Table 23 (p.82) for percent drift ac-
companying a particular type of application. This table shows that from
about 800,000 to 3,000,000 Ib of herbicides were lost during application
due to drift from the 1971 U.S. corn crop. This represents a loss of 0.8
to 3.0% of the total herbicides applied that year.
90
-------
Table 26. ESTIMATED HERBICIDE DRIFT LOSSES FROM THE U.S. CORN CROP (1971)
Time of
application
Preemergent
Subtotal
Post emergent
Subtotal
rr\f\m A T
Method of Type of
application equipment
Broadcast, surface Ground
Air
Broadcast, incorporated Ground
Band Ground
Broadcast, surface Ground
Air
Broadcast, incorporated Ground
Band Ground
Formulation
Spray
Granular
Spray
Granular
Spray
Granular
Spray
Granular
Spray
Granular
Spray
Granular
Spray
Granular
Spray
Granular
Estimated percent
drift over 1,000 ft
from target (%)
Negligible
1
10 to 40
1 to 2
Negligible
Negligible
Negligible
Negligible
Negligible
1
10 to 40
1 to 2
Negligible
Negligible
Negligible
Negligible
Pound s
applied
(000)
33,000
3,700
4,300
1,800
5,600
600
11,100
1.200
61,600
23,000
2,500
2,800
1,200
1,800
200
7 , 100
800
39,400
Pounds lost
(000)
Low
_
39
430
18
-
-
-
-
487
-
25
280
12
-
-
-
-
317
High
_
39
1,720
36
-
-
-
-
1,795
-
25
1,120
24
-
-
-
-
1,169
101,000 804 2,964
-------
The quantity of insecticide drift is estimated from the above assump-
tions, the statistics provided by the five state survey, and the values
for percent drift given in Table 23. In order to do this, the quantities
of insecticides applied to the crop must be determined by formulation,
by method of application, and by type of application equipment. The as-
sumption is made, therefore, that the insecticides were distributed equally
on the acres treated, since the statistics developed under the methods of
application apply to acres treated, not pounds applied.
The amount of insecticides applied to the 1971 corn crop was 25,531,000
Ib. Preemergent applications were 95% of the total, or 24,200,000 Ib, and
postemergent applications were 5% of the total, or 1,300,000 Ib. Preemergent
applications were divided into three methods of application: (a) soil sur-
face broadcast, 5%; (b) soil incorporated broadcast, 15%; and (c) band, 80%.
Postemergent applications were also divided into three methods of ap-
plication: (a) soil surface broadcast, 65%; (b) soil incorporated broad-
cast, 10%; and (c) band, 25%.
The applicators for the preemergent insecticides were: (a) self,
95%; and (b) custom, 5%; and for the postemergent insecticides were:
(a) self, 73%; and (b) custom, 27%.
These statistics give the following information:
Broadcast Surface
applications incorporated Band applications
Time of application (OOP Ib) (OOP Ib) (OOP Ib)
Preemergent 1,200 3,600 19,400
Postemergent 900 100 300
All applications made by the farmer himself are assumed to be ground
equipment applications. This leaves 5% of the preemergent insecticides
available for aerial application by custom applicators and about half (or
3% of the total preemergent applications) of custom applications are as-
sumed to have been made aerially. Likewise, only 27% of the postemergent
92
-------
insecticides were applied by custom applicators, and about half (or 15%
or the total postemergent applications) of these applications arc assumed
to have been made aerially. All aerial applications are surface broadcast
applications since banding and soil incorporating insecticides with air-
craft is impossible.
Table 27 is constructed with the previous assumptions made on formu-
lations used and the values given in Table 23 (p.82) for percent drift
accompanying a particular type of application. This table shows that from
50,000 to 180,000 Ib of insecticides were lost during application due to
drift from the 1971 U.S« corn crop. This represents a loss of 0.2 to 0.7%
of the total insecticides applied that year,
Fungicides - Fungicides used in 1971 on corn were not specified by
the U.S. Department of Agriculture report.—' This report showed that
a total of 1,732,000 Ib of fungicides (excluding sulfur) were used on the
category of crops which includes corn, wheat, sorghum, rice, tobacco, soy-
beans, alfalfa, and sugarbeets, as well as other grains and field crops.
Obviously, the use of fungicides on corn (compared to herbicide and in-
secticide usages) was very small, and any losses of fungicides at the
time of application due to drift from corn crops are negligible.
Other pesticides - Corn was treated with 443,000 Ib of miscellaneous
pesticides (Appendix C, Table C-l). Fumigants accounted for 386,000 Ib
and miticides accounted for the remaining 57,000 Ib. Again, these quantities
are small compared to insecticides and herbicides used on corn, and drift
losses of these pesticides are negligible.
Estimated Pesticide Drift Losses From the U.S. Sorghum Crop (1971) - The
pesticide losses during application due to drift from the 1971 sorghum
crop are estimated in four separate parts: (a) herbicides; (b) insecti-
cides; (c) fungicides; and (d) other pesticides.
Herbicides - The quantity of herbicides applied to the sorghum crop
(1971) are given in Appendix C, Table C-5» Herbicides accounted for
11,538,000 Ib of pesticides used on sorghum.
The formulations of herbicides were primarily wettable powders and
emulsions, with a small usage of granules and no dust usage. Since no in-
formation is available on the exact amount of spray formulations and granules
used that year, sprays are assumed to have accounted for 90% of all formula-
tions, and granules are assumed to have accounted for the remaining 10%
of the formulations.
93
-------
Table 27. ESTIMATED INSECTICIDE DRIFT LOSSES FROM THE U.S. CORN CROP (1971)
Time of Method of Type of
application application equipment
Preemergent Broadcast, surface Ground
Air
Broadcast, incorporated Ground
Band Ground
Subtotal
"^ Postemergent Broadcast, surface Ground
Air
Broadcast, incorporated Ground
Band Ground
Subtotal
Formulation
Spray
Granular
Spray
Granular
Spray
Granular
Spray
Granular
Spray
Granular
Spray
Granular
Spray
Granular
Spray
Granular
Estimated percent
drift over 1,000 ft
from target (%)
Negligible
1
10 to 40
1 to 2
Negligible
Negligible
Negligible
Negligible
Negligible
1
10 to 40
1 to 2
Negligible
Negligible
Negligible
Negligible
Pounds
applied
(000)
100
500
300
300
400
3,200
1,900
17.500
24,200
100
600
100
100
-
100
30
270
1,300
Pounds lost
(000)
Low
_
5
30
3
-
-
-
-
38
-
6
10
1
-
-
-
-
17
High
—
5
120
6
-
-
-
-
131
-
6
40
2
-
-
-
-
48
TOTAL
25,500
55
179
-------
The method of application of herbicides is not known for 1971. The
assumption is made that 10% of the herbicides were applied by aircraft,
and 90% by ground equipment. All aerial applications are broadcast, and
ground applications are assumed to have been divided into three methods
of application as follows: (a) soil surface broadcast, 70%; (b) soil in-
corporated broadcast, 10%; and (c) band, 20%.
These assumptions and the values for percent drift given in Table
23 (p.82) are used to construct Table 28. This table shows that from
120,000 to 450,000 Ib of herbicides were lost during application due to
drift from the 1971 U.S. sorghum crop. This represents a loss of 1.0 to
3.9% of the total herbicides applied that year.
Insecticides - The quantities of insecticides applied to the sorg-
ghum crop (1971) are given in Appendix C, Table C-5. This table shows
that a total of 5,729,000 Ib of insecticides were used on sorghum in
1971.
The formulations and methods of application of insecticides used in
1971 were obtained from interviews with entomologists in the states of
Texas, Oklahoma, Kansas, and Iowa, the leading sorghum producing states.
The information obtained from these interviews indicates that 90% of all
insecticides used on sorghum are aerially applied and only 10% of all
insecticides are applied from ground equipment. Of the 90% aerial appli-
cations, two-thirds are liquid formulations applied to both the soil and
plants, while one-third are granular formulations applied to the soil. Of
the 10% ground equipment applications, 80% (8% of the total insecticides
applied) are liquids applied to the plants, and 20% (2% of the total in-
secticides applied) are granules applied to the soil.
The above information and Table 23 (p.82) are used to construct
Table 29, which shows the estimates for insecticide drift losses from the
1971 sorghum crop. This table shows that from 360,000 to 1,400,000 Ib of
insecticides were lost during application due to drift from the 1971 U.S.
sorghum crop. This represents a loss of 6 to 25% of the total insecti-
cides applied that year.
Fungicides - Fungicides used in 1971 on sorghum were not specified
by the U.S. Department of Agriculture report,.?_§/ which listed sorghum
with corn, as previously mentioned in the fungicide discussion on the
corn crop. The use of fungicides on sorghum is assumed to be small, as
in the case of corn, and any losses of fungicides at the time of appli-
cation due to drift from sorghum crops are negligible.
95
-------
Table 28. ESTIMATED HERBICIDE DRIFT LOSSES FROM THE U.S. SORGHUM CROP (1971)
Method Type of
application equipment
Broadcast, surface Ground
Air
Broadcast, Incorporated Ground
Band Ground
Formulation
Spray
Granular
Spray
Granular
Spray
Granular
Spray
Granular
Estimated percent
drift over 1,000 ft
from target (%)
Negligible
1
10 to 40
1 to 2
Negligible
Negligible
Negligible
Negligible
Pounds
applied
(000)
6,100
700
1,100
100
1,100
100
2,100
200
Pounds lost
(000)
Low High
.
7 7
110 440
1 2
-
-
-
_ _
TOTAL 11,500 118 449
-------
Table 29. ESTIMATED INSECTICIDE DRIFT LOSSES FROM THE U.S. SORGHUM CROP (1971)
VD
Target
Foliar
Foliar and/or soil
Soil
TOTAL
Type of
equipment
Ground
Air
Ground
Air
Formulation
Spray
Spray
Granular
Granular
Estimated percent
drift over 1,000 ft
from target (%)
1
10 to 40
1
1 to 2
Pounds
applied
(000)
500
3,400
100
1.700
5,700
Pounds lost
(000)
Low High
5 5
340 1,360
1 1
17 34
363 1,400
-------
Other pesticides - Sorghum was included in a broad category of
crops—the same one mentioned previously under fungicides used on corn—
that were treated with 3,334,000 Ib of miscellaneous pesticides. Fumi-
gants accounted for 3,124,000 Ib, or over 90% of the total applied. Again,
the use of miscellaneous pesticides on sorghum is considered negligible,
and the losses of these pesticides are negligible also.
Estimated Pesticide Drift Losses From the U.S. Apple Crop (1971) - The
pesticide losses during application due to drift from the 1971 apple crop
are estimated in four separate parts: (a) herbicides; (b) insecticides;
(c) fungicides; and (d) other pesticides.
Herbicides - The quantity of herbicides applied to apple orchards
in 1971 is given in Appendix C, Table C-7. Herbicides accounted for only
197,000 Ib of pesticides used in apple orchards. Their use presents a
special problem in orchards since herbicides commonly used will severely
damage the trees if contact between the trees and herbicides is allowed.
Therefore, special precautions are taken to prevent herbicide drift to
the susceptible trees.
Any drift of herbicides is negligible due to the small quantities
used and the special measures taken to prevent damaging drift in or-
chards.
Insecticides - The quantity of insecticides applied to apple or-
chards (1971) is given in Appendix C, Table C-7. Insecticides accounted
for 4,831,000 Ib of pesticides used in apple orchards.
The formulations of insecticides were primarily wettable powders
and emulsions, with a lesser amount of dust usage and no granular form-
ulation usage. Since no information is available on the exact amounts of
spray formulations and dust formulations used that year, sprays are as-
sumed to have accounted for 80% of all formulations, and dusts are as-
sumed to have accounted for the remaining 20% of the formulations.
The method of application of insecticides to apples in 1971 was pri-
marily that of aerial spraying, airblast spraying, and high volume spray-
ing. Since the relative amounts of each method are not known, the assump-
tion is made that half the dusts were applied aerially to the trees, and
that the other half of the dusts were applied to the trees with an orchard
airblaster. The liquid sprays are assumed to have been applied both as
an LV application with an airblaster—75% of the total spray applications—
and as an HV application with a high pressure spray gun—25% of the spray
applications. (Some aerial liquid spray application was undoubtedly per-
formed, but the drift loss from aerial spray applications and LV airblaster
applications are the same.)
98
-------
The quantity of insecticide drift is determined from the above as-
sumptions and the information given in Table 23 (p. ). These data are
used to construct Table 30, which shows the estimated insecticide drift
losses from the 1971 apple crop. (All insecticide applications are fo-
liar in apple orchards.) This table shows that from about 1,000,000 to
2,000,000 Ib of insecticides were loss during application due to drift
from the 1971 apple crop. This represents a loss of 21 to 42% of the
total insecticides applied that year.
Fungicides - The quantity of fungicides applied to apple trees (1971)
is given in Appendix C, Table C-7. Fungicides accounted for 7,207,000 Ib
of pesticides used in apple orchards.
The method of application and formulations used are assumed to have
been the same as those for insecticides. Therefore, the percentage loss
of fungicides was about the same as that for insecticides (between 21
and 42%) and the quantities of fungicides lost due to drift were between
1,500,000 and 3,000,000 Ib in 1971.
Other pesticides - Miscellaneous pesticides applied to apple orchards
(1971) consisted of 367,000 Ib of miticides; 174,000 Ib of plant growth
regulators; and 7,000 Ib of rodenticides. These pesticides brought the
total miscellaneous pesticide use on apple orchards to 548,000 Ib. This
quantity is small relative to the usage of insecticides and fungicides on
apples in 1971, and the drift loss of the miscellaneous pesticides listed
above is negligible.
99
-------
Table 30. ESTIMATED INSECTICIDE DRIFT LOSSES FROM THE U.S. APPLE CROP (1971)
o
o
Type of
equipment
Airblaster
Spray gun
Aircraft
TOTAL
Formulation
Dust
Spray
Spray
Dust
Estimated percent
drift over 1,000 ft
from target (%)
60 to 80
10 to 40
3 to 5
70 to 90
Pounds
applied
(000)
500
2,800
1,000
500
4,800
Pounds lost
(000)
Low
300
280
30
350
960
High
400
1,120
50
450
2,020
-------
REFERENCES TO SECTION III
1. Akesson, N. B., and W. E. Yates, "Problems Relating to Application
of Agricultural Chemicals and Resulting Drift Residues," Annual
Review of Entomology. 9^:285-318 (1964).
2. Polon, J. A., "Formulation of Pesticidal Dusts, Wettable Powders,
and Granules," Pesticide Formulations, Marcel Dekker, Inc., New
York (1973).
3. Perry, J. H., Chemical Engineers Handbook, Third Edition, McGraw-
Hill Book Company, Inc., New York (1950).
4. Myram, C., and J. D. Forrest, "The Application of Pesticide Gran-
ules from the Air," Chemistry and Industry, pp. 1851-1852,
27 December 1969.
5. Ware, G. W., B. J. Estesen, W. P. Cahill, P. D. Gerhardt, and K. R.
Frost, "Pesticide Drift I: High Clearance vs. Aerial Application
of Sprays," J. Econ. Entomol.. 62(4):840-843 (1969).
6. Courshee, R. J., "Some Aspects of the Application of Insecticides,"
Annual Review of Entomology, 5:327-352 (1960).
7. Telephone contact with Mr. Ferrel Higby, Executive Secretary, Na-
tional Agricultural Aviation Association, Washington, D.C.
8. Principles of Farm Machinery, Second Edition, The AVI Publishing
Company, Inc. (1972).
9. Beasley, E. M., and J. W. Glover, "Orchard Spray Equipment," North
Carolina Agricultural Extension Service, Circular 501, January
1969.
10. Chamberlin, J. C., C. W. Getzendaner, H. W. Hessig, and V. D. Young,
"Studies of Airplane-Spray Deposit Patterns at Low Flight Levels,"
USDA Technical Bulletin No. 1110, May 1955.
11. Yeo, D., "The Problem of Distribution, The Physics of Falling Drop-
lets and Particles. The Drift Hazard," First International Agri-
cultural Aviation Conference, 15-18 September, Cranfield, England,
International Agricultural Aviation Centre, The Hague, pp. 112-130
(1959).
101
-------
12. Yates, W. E., and N. B. Akesson, "Reducing Pesticide Chemical Drift,"
Pesticide Formulations, Marcel Dekker, Inc., New York (1973).
13. Colthurst, J. P., R. E. Ford, C. G. L. Furmidge, and A. J. A. Pearson,
"Water-in-Oil Emulsions and the Control of Spray Drift," Symposium
on The Formulation of Pesticides, S.C.I. Monograph No. 21, Society
of Chemical Industry (1966).
14. Akesson, N. B., and W. E. Yates, "Physical Parameters Relating to
Pesticide Application," Personal Communication.
15. "Agricultural Spray Nozzles and Accessories," Spray Systems Company,
Catalogue 35.
16. Yates, W. E., and N. B. Akesson, "Characteristics of Drift Deposits
Resulting from Pesticide Applications with Agricultural Aircraft,"
Third International Agricultural Aviation Congress, Proceedings,
The Hague, Netherlands (1966).
17. Amsden, R. C., "Reducing the Evaporation of Sprays," International
Agricultural Aviation Center, The Hague, Agricultural Aviation,
4_:88-93 (1962).
18. Hartley, G. S., "The Physics of Spray Drift," First International
Agricultural Aviation Conference, 15-18 September, Cranfield,
England, International Agricultural Aviation Centre, The Hague
(1959).
19. Edwards, C. J., and W. E. Ripper, "Droplet Size, Rates of Applica-
tion, and the Avoidance of Spray Drift," British Weed Control Con-
ference, Proceedings, pp. 347-368 (1953).
20. Aerial Spraying Manual, Spray Systems Company.
21. Bowers, W., "Reducing Drift of Spray Droplets," OSU Extension Facts,
No. 1203.
22. Akesson, N. B., W. E. Yates, and S. E. Wilce, "Needed: Better Drift
Control, Pesticide Drift Control Results Summarized for 1972,"
Agrichemical Age, pp. 9-12, December 1972.
23. Akesson, N. B., S. E. Wilce, and W. E. Yates, "Confining Aerial Ap-
plications to Treated Fields--A Realistic Goal," Agrichemical Age,
pp. 11-14, December 1971.
102
-------
24. Wisconsin Statistical Reporting Service, "General Farm Use of Pes-
ticides (1971)--Wisconsin, Illinois, Michigan, and Minnesota,"
Wisconsin Department of Agriculture, Division of Administration,
255-72.
25. U.S. Department of Agriculture, "1970 Pesticide Usage on Farms--
Indiana and Five Lake States," Purdue University, Agricultural
Experiment Station, Department of Agricultural Statistics, West
Lafayette, Indiana.
26. U.S. Department of Agriculture, "Farmers' Use of Pesticides in
1971 . . . Quantities," Agricultural Economic Report No. 252,
Economic Research Service, Washington, D.C. (19745).
103
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SECTION IV
PESTICIDE LOSSES AFTER APPLICATION AND BY MISCELLANEOUS DISCHARGES
INTRODUCTION
There are several potential sources of pesticide waste which occur
both after pesticide application to the crop and due to miscellaneous
pesticide discharges. These losses reduce the efficiency of pesticide
usage in agriculture. The pesticide losses which occur after application
are due primarily to the unwanted migration of effectively applied pes-
ticides from the treated crop by the natural forces of runoff and soil
erosion. Miscellaneous pesticide discharges into the environment result
from pesticide spills and from disposal of unused pesticides and incom-
pletely emptied containers.
This section examines both the transport of pesticides from crops
by the mechanism of runoff and soil erosion and the miscellaneous dis-
charges of pesticide spills and pesticide disposal. Each subject is
given both a qualitative and a quantitative treatment as it is discussed.
In the case of runoff and soil erosion, the amount of pesticides lost
from the U.S. corn, sorghum, and apple crops (1971) is determined. Pes-
ticide losses from spills and disposal are not determined quantitatively,
since the nature of these subjects does not permit an accurate determina-
tion to be made.
Each of the above subjects are examined separately in the following
discussion.
PESTICIDE LOSS DUE TO RUNOFF AND SOIL EROSION
The principal mechanisms of pesticide transport away from field
crops after application are: (a) surface runoff including both sediment
and water; (b) volatilization; (c) leaching to ground water; and (d) deg-
radation by chemical, photochemical, or microbial processes. The magnitude
of the losses vary with each pesticide and environmental condition. Gen-
erally, surface runoff, volatilization, and degradation are the dominant
104
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mechanisms for pesticide loss from cropland. Volatilization and degrada-
tion, however, are processes which are beyond the control of the farmer
once the pesticide has been properly applied. Since this study deals with
the inefficient use of pesticides, only surface runoff and erosion are
considered.
Before discussing the mechanisms of runoff and erosion and their ef-
fect on pesticide losses from the study crops, it is important to realize
that some of the losses occurring by these two mechanisms are, in reality,
beyond man's control. Surface runoff and soil erosion occur even under the
best soil conservation practiced today. The approach to this subject, then,
must be one that examines not only the incidence of pesticide losses, but
methods by which these losses can be reduced through man's efforts.
This section is divided into the following subsections:
1. Field Crop Runoff and Soil Erosion.
2. Management Practices in Field Crops.
3. Pesticide Losses in Runoff and Soil Erosion.
4. Estimated Runoff from the U.S. Corn and Sorghum Crops - Quanti-
ties.
5. Estimated Pesticide Losses from the U.S. Corn, Sorghum, and
Apple Crops in 1971 - Quantities.
Field Crop Runoff and Soil Erosion
Pesticides applied to the soil of corn and sorghum crops are subject
to removal from the crop by transport in runoff water and eroded soil.
Runoff occurs in two different manners—overland and subsurface runoff.
Overland runoff represents surplus water which leaves the crop above the
soil surface, whereas subsurface runoff represents residual water not ac-
commodated by the soil. Likewise, soil erosion occurs when wind trans-
ports soil at rest. Since most investigations of pesticide losses from
crops due to runoff and soil erosion have studied surface runoff and the
accompanying sediment losses, and since wind erosion and subsurface run-
off are subject to less control than the other two mechanisms, only sur-
face runoff and surface soil erosion by water are considered here.
Runoff and soil erosion occur from both natural and man-made events.
Nature provides rain and man irrigates. Irrigation can cause erosion if
water is applied at rates which exceed the rate of infiltration into the
105
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soil, and, consequently, water runs off the crop. By employing proper
techniques to insure that irrigation to the point of runoff and soil
transport away from the crop is avoided, the farmer also avoids pesti-
cide loss during crop irrigation. Since irrigation is controllable, and
the best interests of the farmer are served if excessive water (which is
expensive and sometimes scarce) is not used, then pesticide losses from
crops due to irrigation practices are most likely negligible. Therefore,
this study examines rainfall events only.
The damage caused by raindrops hitting the soil at a high velocity
is the first step in the runoff and erosion process. Raindrops shatter
the soil granules and clods, reducing them to smaller particles and thereby
reducing the infiltration capacity of the soil. The small soil particles
are then detached by additional rainfall, and the force of the raindrops
starts the movement of splashed soil downslope. When the rate of rainfall
exceeds the rate of infiltration, depressions in the soil surface fill and
overflow, causing runoff. The runoff water picks up the detached soil par-
ticles, and breaks the now suspended particles into smaller sizes. The
flow of the runoff water transports the suspended soil particles, and to-
gether both the water and sediment move off the crop. This basic mechanism
of soil erosion was defined by Meyer and Wischmeieci/ as falling into four
categories: (a) soil detachment by raindrops; (b) transport by rainfall;
(c) detachment by runoff; and (d) transport by runoff.
When rainfall occurs, the risk that pesticides in the soil will be
transported from the field in the runoff water and/or sediment is great
and is directly related to those factors which effect surface erosion.
Factors which have been considered the most significant in affecting ero-
sion of topsoil are:
1. Soil properties;
2. Slope characteristics;
3. Land cover conditions;
4. Rainfall characteristics; and
5. Conservation treatment.
Soil Properties - Soil properties affect both the detachment and trans-
port processes. Detachment is related to soil stability (basically the
size, shape, composition), and strength of soil aggregates and clods.
Transport is influenced by permeability of soil to water which deter-
mines infiltration capabilities and drainage characteristics; by porosity,
which affects storage and movement of water; and by soil surface rough-
ness, which creates a potential for temporary detention of water.
106
-------
Slope Characteristics - Slope characteristics are represented by the
slope factor which defines the transport portion of the erosion process.
It is exemplified by slope gradient and slope length, both of which in-
fluence the flow and velocity of runoff.
Land Cover Conditions - Land cover conditions affect detachment and trans-
portation of soil. Land cover by plants and their residues provides pro-
tection from the impact of raindrops. Vegetation protects the ground from
excessive evaporation, keeps the soil moist, and thus, makes the soil ag-
gregates less susceptible to detachment. In addition, residues and stems
of plants furnish resistance to overland flow, slowing down runoff ve-
locity and reducing erosion.
Rainfall Characteristics - Rainfall characteristics define the ability
of the rain to splash and erode soil. Rainfall energy is determined by
drop size, velocity, and intensity characteristics of rainfall.
Conservation Treatment - Conservation treatment concerns modification of
the soil factor or the slope factor, or both, as they affect the erosion
sequence. Practices for erosion control are designed to do one or more of
the following: (a) dissipate raindrop impact forces; (b) reduce quantity
of runoff; (c) reduce runoff velocity; and (d) manipulate soils to en-
hance the resistance to erosion.2./
The factors discussed above indicate that the amount of soil loss
and runoff are within the control of the farmer to the extent that he
uses good conservation practices. By minimizing runoff and erosion, the
risk of pesticide loss is substantially reduced. The next section ex-
amines the effect of management practices on soil conservation.
Management Practice in Field Crops
Management practices that directly affect the loss of pesticides
from corn and sorghum crops are those that reduce runoff and erosion.
Recognition of the need for good conservation practices as a means to
reduce runoff and erosion has existed a long time. The Universal Soil
Loss Equation (USLE), developed by Wischmeier and Smith,.!/ is a good ex-
ample of the importance that cropping practices and erosion control prac-
tices have on soil erosion. The equation is used to compute the annual
average soil loss (sheet and rill erosion) per unit area (tons/acre/year).
The equation is:
E = R'K'L'S-C'P
107
-------
where R is the rainfall factor; K is the soil erodibility factor;
L is the slope-length factor; S is the slope gradient factor; C is
the cropping management factor; and P is the erosion-control practice
factor.
For our purposes, the main consideration here are the C and P fac-
tors. These factors were built into the equation since it was recognized
that management practices used by farmers had a definite, and often sig-
nificant, effect on soil erosion from their crops. The C factor—cropping
management factor—is the ratio of soil loss from a field with specified
cropping and management to that from the fallow condition on which the K
factor is evaluated. This factor reflects the influence of type of vege-
tal cover, seeding method, soil tillage, disposition of residues, and
general management level. The P factor—erosion-control practice factor—
is the ratio of soil loss with contouring, stripcropping, or terracing
to that with straight-row farming, up and down slope. This factor repre-
sents the effects contouring, contour stripcropping, terracing, and di-
version have on soil loss.
To show the relative magnitude of the effects farm management can
have on soil loss, Table 3lA/ gives the practice values for contouring,
contour strippcropping and terracing. Thus, it is evident that if other
factors remain the same for a given crop, contour stripcropping, for ex-
ample, on a slope of 2 to 77», would reduce soil loss by 75%.
As a further illustration, the Agricultural Research Serviceft' pub-
lished some examples of the use of USLE in watershed planning to show the
effect conservation practices can have on soil management. In one of the
examples, soil loss from a 280 acre crop of corn is compared under pres-
ent conditions and future conditions. The present conditions are: (a)
continuous corn with residue removed—average yield 70 bu/acre; and (b)
cultivated up and down slope. The future conditions are: (a) rotation
of wheat, meadow, corn, corn with residue left; and (b) contour strip-
cropping. All other conditions of soil (Fayette silt loam), slope (87»),
and slope length (200 ft) remain constant.
Under the present conditions, the C factor is 0.43 and the P factor
is 1.00, while under the future conditions the C factor (reflecting crop
rotation) is 0.119 and the P factor (reflecting contour stripcropping)
is 0.30. The calculations show that soil loss under present conditions
is 41.5 tons/acre/year compared to 3.4 tons/acre/year under future con-
ditions. The effects of good management shown by this example are self-
evident.
108
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Table 31. "P" VALUES FOR CONTOURING, CONTOUR
STRIPCROPPING, AND TERRACING
P values contour Terracing
Land slope (%)
2.0 to 7
8.0 to 12
13.0 to 18
19.0 to 24
Contouring
0.50
0.60
0.80
0.90
stripcropping — '
0.25 0.50
0.30 0.60
0.40 0.80
0.45 0.90
±1
0.10
0.12
0.16
0.18
a/ For erosion-control planning on farmland.
b/ For prediction of contribution to off-field sediment load.
Source: "Procedure for Computing Sheet and Rill Erosion on Project Areas,"
Technical Release No. 51, Soil Conservation Service, U.S. Depart-
ment of Agriculture (1972).
109
-------
An additional example will help illustrate the importance of crop-
ping practice. Soil losses are the greatest when a field is fallow or
bare of cover and are reduced as crops are introduced, and as good crop-
ping practices are used. Table 322.' illustrates that a cropping practice
of continuous corn gave a soil loss of 19.72 tons/acre/year, and rotation
of corn, wheat, and clover gave a loss of 2.78 tons/acre/year. There was
a corresponding reduction of runoff as a percentage of rainfall.
Obviously, good management in farm operations is important to the
reduction of runoff and erosion. However, there is evidence that good
management practices are not used throughout agriculture, and that a large
potential for further erosion and runoff control of pesticides in crop
soils exists today.
In support of the statement that good management practices are want-
ing, the following data were obtained from a report written by Shrudar
"The total land area in Illinois is about 35.7 million
acres; 24.4 million acres are used for tilled crops. In 1967,
about 727o of the tilled soil was devoted to corn and soybeans.
An inventory of conservation needs indicates that 66% of this
crop land acreage is not adequately treated. The most needed
conservation practices, with the percent of crop land involved
are:
Contour farming 10.5%
Terraces or diversion 10.57o
Cover crops 20.0%
Crop rotation 9.0%
Drainage 13.0%
A review of the acreage of crop land on a county basis
showed that 11 of the 102 counties in Illinois required ad-
ditional treatment on 60% or more of the total crop land
within their boundaries."
The method farmers use (or do not use) to rotate crops, till the
soil, practice erosion control and apply good crop management techniques
in general to their crops has a profound effect on the runoff and erosion
experienced in agriculture. Since pesticides (as will be shown in subse-
quent sections) are transported from crops in both runoff water and sedi-
ment losses, it is necessary that good management is used to reduce these
chemical losses into the environment. Though some of the nation's farms
do minimize chemical losses through conservation, others do not. Those
110
-------
Table 32. EFFECTS OF DIFFERENT CROPPING SYSTEMS ON RUNOFF AND EROSION
Soil loss Runoff
Cropping practice (tons/year) (% of rainfall)
Continuous bluegrass 0.34 12.0
Rotation of corn, vheat, clover 2.78 13.8
Continuous wheat 10.09 23.3
Continuous corn 19.72 29.4
Fallow 41.65 30.7
Source: "Agricultural Pollution of the Great Lakes Basin," Report by
Canada and the United States, U.S. Environmental Protection
Agency, Water Quality Office (1971).
Ill
-------
that do not must be considered inefficient in the use of pesticides in
this respect.
Pesticide Losses in Runoff and Soil Erosion
Pesticides applied to crops are subject to transport away from the
crop in runoff water and sediment. A number of studies have been con-
ducted to substantiate that losses do occur, and several of these studies
are presented in Appendix B. Other studies are in progress to determine
the magnitude of these losses, and better statistics should be available
in the future to quantify these losses. After presentation of the studies
the quantities of pesticides in runoff and soil erosion are estimated.
In order to ultimately determine the quantities of pesticides trans-
ported from the soil of crops, two approaches are possible. The first is
to determine the concentration of pesticides in both the runoff and sedi-
ment, determine the volume of runoff and weight of sediment transported
from each crop, and then multiply the concentrations times the volume or
weight to arrive at the total pesticide loss. The second method is to de-
termine the pesticide loss from the crops as a percent of the quantity
applied, determine the amount of pesticides applied to the crops, and
then multiply the percentage loss times the amount applied to arrive at
the total pesticide loss.
This study examines both methods. There are, however, difficulties
involved in either approach, and these problems can be summarizes as fol-
lows :
1. There is no current method of accurately determining the amount
of runoff or the amount of sediment lost from crops. Use of the USLE is
the best method to predict soil erosion, but the six variables in the
equation vary widely throughout the United States. Annual runoff statis-
tics are available from the U.S. Geological Survey,Z' but these statistics
cover all land areas, not just crops.
2. The concentrations of pesticides in sediment and runoff vary
with pesticide characteristics, such as solubility, volatility, polarity,
and degree of association; and with soil characteristics such as mois-
ture, soil acidity, porosity, and bacterial population, just to name a
few parameters.
3. The investigations conducted on pesticide concentrations in run-
off and sediment that were found in this study are finite. They each apply
to circumstances in which many of the variables involved are fixed (such
112
-------
as soil slope, soil type, rainfall, etc.). Obviously, the results of such
studies cannot be applied to a general case for all croplands without
some degree of error.
The three difficulties cited above are the major ones and they are
insurmountable with regard to quantifying the crop pesticide losses with
accuracy. However, the objective of this study is to quantify the losses
and an attempt to do so is made. Even if reasonable estimates are later
deemed impossible to make, the reason can be determined from the diffi-
culties encountered along the way.
Only runoff is considered in the first method cited above since there
are two methods (discussed later) that can be used to make a gross esti-
mate of the amount of runoff from the study crops. On the other hand, any
estimate of total soil loss from the study crops would be so gross that
it would be useless. Until a method for calculating the amount of soil
loss from croplands is found, the use of the first method for determin-
ing pesticide losses in soil erosion (that is, concentration of pesticide
in soil times weight of soil lost) is not feasible.
Appendix B gives the field studies on pesticide runoff after appli-
cation obtained from the literature. It is divided into two sections, al-
though some of the field investigations cited appear in both sections.
The first section presents concentrations of pesticides found in runoff
waters from croplands. The second section presents total quantities of
pesticides lost from crops as a percent of the quantity applied, for both
runoff and sediment transport considered as a whole.
The above studies do not investigate all of the pesticides that are
of major importance to the three study crops. The major herbicides are:
(a) atrazine; (b) propazine; (c) propachlor; (d) alachlor; (e) 2,4-D;
and (f) butylate. The major insecticides are: (a) aldrin; (b) buxj (c)
carbofuran; (d) phorate; (e) diazinon; (f) carbaryl; (g) parathion; and
(h) methyl parathion. Since not all these pesticides have been studied,
it is necessary to estimate the concentrations each would have in runoff.
Before doing this, however, we must introduce an important point.
A major aspect of the problem of quantifying the losses is the timeli-
ness of the runoff experience. Figure 1L§' shows the persistence of se-
lected pesticides in soils. These data show the time required for a 75
to 100% reduction in the initial amount of pesticide applied under normal
soil conditions using normal application rates. Therefore, this fact is
considered when quantifying the pesticide losses, and the assumption is
made that when the time period that a pesticide remains in the soil after
application exceeds the value given in Figure 11, the pesticide losses
are negligible.
113
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Organochlorine Insecticides
Heptachlor, Aldrin, Metabolites
_i i \ i i i
234
Years
Phosphate Insecticides
Malathion, Parathion
468
Weeks
10 12
Urea, Triazine, and Picloram Herbicides
Benzoic Acid and Amide Herbicides
Propazine, Picloram
••H
Simazine
mamm
Atrazine, Monuron
mmm
Diuron
^H
Linuron, Fenuron
Mi
Prometryne
i i i i
0 2 4 6 8 10 12 14 16 18
Months
Diphenamide
••I
Amiben
•u
CDAA, Dicamba
6 8 10 12
Months
Phenoxy, Toluidine, and Nitrite Herbicides Carbamate and Aliphatic Acid Herbicides
234
Months
12
Source:
Figure 11. Persistence of individual pesticides in soils.
Kearney, P. C., and Helling, C.S., "Reactions of Pesticides in
Soils," Residue Reviews. Vol. 25 (1969).
114
-------
Not all of the important pesticides are given in Figure 11. However,
with the use of other references, Table 33 is constructed to show the max-
imum length of time during which runoff and erosion losses occur for each
pesticide.
Alachlor and butylate were not investigated in the field studies
presented in Appendix B. Alachlor and propachlor are both acetanilides
made by the same company and are assumed to be present in runoff in sim-
ilar concentrations and to have the same soil persistence. Butylate is
a thiocarbamate and is chemically dissimilar from the other herbicides
studied. Therefore, butylate is excluded from further consideration.
The insecticides aldrin, bux, carbaryl, phorate, parathion, and
methyl parathion were not investigated in the studies presented in Ap-
pendix B. Aldrin is a highly chlorinated cyclic hydrocarbon with a very
low solubility (0.027 ppm).2/ and is chemically similar to both dieldrin
and endrin, whose solubilities are 0.86 ppm and insoluble,—' respectively.
(Solubilities are compared since these chemicals are the only ones studied
whose solubities seem to make a difference. All the other chemicals had
solubilities well above the concentrations found in the runoff.) Aldrin
will be assumed to have concentration values similar to endrin and diel-
drin. Parathion and methyl parathion are organophosphorus compounds sim-
ilar to diazinon and will assume the same values. Bux, carbaryl, and
phorate are dissimilar to the other insecticides studied, and will not
be considered, since any estimation would be a mere guess.
Table 34 is constructed from the information presented in Table 33
and in the field studies cited in Appendix B. It presents the estimated
concentration of pesticide that can be expected in runoff water for a
runoff event occurring within a specified time interval after the pesti-
cide is applied.
The amount of loss from ground runoff and soil erosion depends upon
rate of application, type of soil surface, and depth of application. These
factors are taken into account, and Table 35 gives the loss of the pesti-
cides studied in Appendix B as a percent of the total applied. Unfortun-
ately, this table is not entirely representative of possible losses since
important factors such as soil type, soil slope, amount of rainfall, and
occurrence of rain immediately after application are important factors,
also. However, this table should give a good approximation to the losses
to be expected when using these pesticides.
The next step is to construct a table similar to Table 34, showing
the expected range of values for the percentage loss with respect to the
time the pesticide has remained in the soil. Since the studies in Appendix
B were limited to only six of the important pesticides, some assumptions
must be made.
115
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Table 33. PERIOD OF TIME AFTER APPLICATION IN WHICH PESTICIDES
ARE SUBJECT TO RUNOFF LOSSES
Herbicide Time (weeks) Insecticide Time (weeks)
Alachlor Unavailable Aldrin 156
Atrazine 48 Carbofuran 10-
2,4-D 4 Diazinon 12
Propachlor 6^' Methyl parathion 2~
Propazine 78 Parathion 1
a/ Source: "The Effects of Agricultural Pesticides in the Aquatic
Environment, Irrigated Croplands," San Joaquin Valley,
Office of Water Programs, Environment, American
Chemical Society, Washington, D.C.
b/ Source: Pesticide Manual, Second Edition, British Crop Protection
Council (1971).
116
-------
.Table 34. ESTIMATED CONCENTRATION OF PESTICIDES IN RUNOFF^'
Pesticide
Herbicides
Alachlor
Atrazine
2,4-D
Propachlor
Propazine
Insecticides
Aldrin
Carbofuran
Diazinon
Methyl pa rath ion .
Pa rath ion
Time in
soil (weeks)
. 1 (First storm)
1-6
1 (First storm)
1-48
1 (First storm)
1-4
1 (First storm)
1-6
1 (First storm)
1-78
156
1 (First storm)
10
12
2
1
Concentration in runoff
Low
100
10
1,000
10
1,000
10
100
10
1,000
10
1
1,000
10
5
5
5
Typical
500
50
1,500
50
1,800
50
500
50
1,500
50
2
2,000
50
10
10
10
(ppb)
High
800
100
2,500
200
2,500
100
800
100
2,500
100
10
3,000
100
20
20
20
£/ This table reflects the fact that the largest concentrations in runoff occur with the first rainstorm.
If a storm should occur within the first week after application, the concentration of pesticide in the
runoff from that storm is so indicated. The second set of values given for each pesticide with a first
storm value indicate the estimated concentrations in each runoff event occuring after the first week.
Aldrin, diazinon, methyl parathion, and parathion have small concentrations even during the first week
after application.
-------
Table 35. SUMMARY OF PESTICIDE LOSSES DETERMINED FROM FIELD STUDIES IN APPENDIX B
oo
Pesticide
Carbo f uran
Dieldrin
Picloram
Diazinon
Propachlor
Atrazine
2,4-D Butyl
ester
2,4-D Amine
ester
a/ No soil
V Due to s
Type of
soil surface
Plowed, planted
Furrowed, planted
Furrowed, planted
Plowed, planted
Cultipacked, planted
Plowed
Ridged, planted
Contoured, planted
Contoured, planted
Ridged, planted
Contoured, planted
Ridged, planted
Contoured, planted
Ridged, planted
Contoured, planted
Ridged, planted"
Smooth
Smooth
Unknown
Unknown
erosion involved, just runoff water.
oil erosion.
Depth of
application
(in.)
3
2
2
3
3
Unknown
1-2
1-2
Surface
Surface
Surface
Surface
Surface
Surface
Surface
Surface
Surface
Surface
Unknown
Unknown
Rateof
application
(Ib/acre)
4.83
3.71
2.77
5.0
5.0
5.0
1.0
1.0
4.0
4.0
6.0
6.0
2.0
2.0
3.0
3.0
3.0
3.0
2.2
1.2
Loss as 7. of
total applied
0.9
0.5
1.9
0.007£/
2.2>>/
0.0&£/
Insignificant!/
O.l!/
Insignificant!/
Insignificant!/
3.1
Insignificant!/
8.2
3.9
16. OS./
2.7S.I
2.0 to 7.3
2.5
13
4
£/ Water runoff only.
d_/ No heavy
rains during year of application.
e/ Heavy rain just 7 days after application removed ~ 907. of total loss.
-------
Alachlor, butylate, and propazine were not investigated. Propazine
and atrazine are both triazines and have similar properties, so the
losses of atrazine are assumed to be representative of those for propa-
zine as well. Alachlor and propachlor are both acetanilides, and alachlor
is assumed to be.similar to propachlor in soil and runoff losses. Buty-
late is unrelated to any of the pesticides previously discussed and is
excluded from further consideration.
Aldrin, methyl parathion, and parathion were not studied. Aldrin is
a highly chlorinated cyclic hydrocarbon similar to dieldrin, and values
of losses for aldrin are assumed to be the same as for dieldrin. Methyl
parathion and parathion are organophosphorus compounds similar to di-
azinon, and are given the same values obtained for diazinon.
Making the above assumptions and with the information presented in
the field studies, Table 36 is constructed to show the expected percent-
age loss of each pesticide from the soil to which it is applied. This
table is used later to quantify the pesticide losses from the study crops.
Any estimates on the amount of pesticide lost due to runoff and ero-
sion must take into account the importance of the time element involved.
When storms do not occur within a week or two of application, the amount
of pesticide loss is substantially reduced.
Estimated Runoff from the U.S. Corn and Sorghum Crops - Quantities
The quantification of runoff is done by two methods in order to see
how the predictions compare. The first method uses the average annual run-
off map constructed by the U.S. Geological Survey!' in combination with
the average seasonal runoff map.!?-' for the spring months of April, May
and June. These maps are used to estimate the total crop runoff from both
corn and sorghum crops during those months. The second method uses maps—i'
showing the mean total precipitation (inches) by state climatic divisions,
for each of the months of April, May and June. The rainfall statistics
given on the maps are used to calculate the amount of runoff by assuming
a certain percentage of the rainfall runs off the crops. Each method is
described in detail below.
Method 1 - Average Seasonal Runoff - Average annual runoff is a variable
phenomenon and is determined on the basis of continuing measurements of
stage and discharge at 8,400 gauging stations throughout the U.S. They
collect data that are analyzed and plotted by the U.S. Geological Survey
to produce the annual average runoff map. This map is shown as Figure 12.
119
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Table 36. PERCENT PESTICIDE LOSS FROM CROPS AS A PERCENT OF THE TOTAL AMOUNT APPLIED^'
a/
N3
O
Pesticide
Herbicides
Alachlor
Atrazine
2,4-D
Propachlor
Propazine
Insecticides
Aid r in
Carbofuran
Diazinon
Methyl parathion
Parathion
Time in
soil (weeks)
1 (First storm)
1-4
1 (First storm)
1-48
1 (First storm)
1-4
1 (First storm)
1-4
1 (First storm)
1-78
1-156
1 (First storm)
1-10
.1 (First storm)
1-12
2
1
Loss due
Low
0.5
0.0
0.5
0.5
1.0
0.05
0.5
0.0
0.5
0.5
0.5
0.5
0.0
0.01
Negl.
0.01
0.01
to runoff and erosion (%)
Typical
1.0
0.5
2.0
1.0
3.0
0.1
1.0
0.5
2.0
1.0
1.0
1.0
0.1
0.05
Negl.
0.05
0.05
High
3.0
1.0
5.0
2.0
5.0
0.3
3.0
1.0
5.0
2.0
2.0
2.0
0.2
0.1
Negl.
0.1
0.1
a/ This table reflects the fact that the heaviest losses occur with the first rainstorm. If a storm
should occur within the first week after application, the amount of pesticide lost in that storm
is so indicated. The second set of values given for each pesticide with a first storm value indi-
cate the percent loss expected for the time period indicated. If a storm does not occur within
the first week, these values are used. If a storm does occur in the first week, the total loss
for the entire time period is the sum of the two values. Timing of the storm has no appreciable
affect on aldrin, methyl parathion, or parathion.
-------
Over 102 cm
2.5-10 Inches
10-20 Inches
20-40 Inches
Over 40 Inches
Source: U.S. Geological Survey, National Atlas
of the United States of America,
Washington, D.C. (1970).
Figure 12. Average annual runoff.
-------
to
IS3
30
40
50
40
30
20
Source:
U.S. Department of
Agriculture, Water: The
Yearbook of Agriculture, 1955,
pp. 58-59, Washington, D.C. (1955).
Figure 13. Average seasonal runoff, percent of total annual runoff,
spring months—April, May, and June.
-------
The period April through June is the most critical in this study.
The vast majority of herbicides and insecticides applied to corn and sor-
ghum are applied at the beginning of this period, and since the greatest
pesticide losses occur soon after application, the amount of runoff in
this period is critical in determining the amounts of pesticide lost from
this mechanism.
To calculate the amount of runoff in April, May and June, the map
showing the average seasonal runoff, percent of total annual runoff,
spring months—April, May and June is used. This map is shown as Figure
13. Multiplying the percentages given on this map times the annual run-
off statistics provided by Figure 12 gives the runoff for the 3-month
period.
Unfortunately, these maps provide runoff for the entire U.S. land
area, not just the agricultural. Some areas, such as pastures, forests,
and grassland, have very low runoff values, while others, such as fallow
or bare ground, have high runoff values. Since the topography and land
use vary widely across the country, a range of values is given for the
runoff predictions from the two crops.
Tables 37 and 38 show the runoff predictions for corn and sorghum,
respectively. The acreages are obtained from Appendix C, Figures C-2 and
C-3; the annual runoff values (inches) are estimated from Figure 12; and
the percentage runoff experienced for the months of April, May and June
are taken from Figure 13.
Method 2 - Rainfall Statistics - The rainfall statistics maps provided by
the U.S. Department of Commerce are shown in Figures 14, 15, and 16.— '
These statistics are more accurate for our purposes than the runoff sta-
tistics. However, the error in this method develops when the amount of
rainfall is correlated with the amount of runoff resulting from that rain-
fall. Runoff, as in the case of erosion, varies widely within the total
crop and depends upon many of the same factors that affect erosion.
To predict the amount of runoff, it is necessary to calculate the
percent of rainfall that runs off the two crops. Again we are faced with
a gross estimate since cropping practices, soil types, soil slopes, etc.,
vary widely over the crops. Table 32 (p. Ill),shows that the percentage
of rainfall that runs off a crop varies with the cropping practice used,
and this table provides some gross estimates of the percentages involved.
The amount of runoff as a percentage of rainfall is 30.770 for fallow
ground; 29.4% for continuous corn; and 12.0% for continuous bluegrass.
123
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Table 37. ESTIMATED CORN CROP RUNOFF IN APRIL, MAY, AND JUNE (METHOD ONE)
ISJ
Annual runoff (in.)
Region
Northeast
Lake States
Corn Belt
Northern Plains
Appalachian
Southeast
Delta States
Southern Plains
Mountain
Pacific
Acres (000)
3,600
12,000
35,400
12,000
4,700
3,400
400
800
1,100
500
Low
7
4
7
1
10
10
4
1
1
1
High
15
10
15
2
25
20
8
2
2
2
Spring
Spring acre-inches
runoff (%)
35
45
35
45
30
30
35
50
50
35
Low
8
22
87
5
14
10
0.6
0.4
0.6
0.2
runoff Spring runoff
(millions) (10*° Ib)
High
19
54
186
11
35
20
1
0.8
1
0.4
Low
180
500
1,970
110
320
230
15
10
15
5
High
430
1,220
4,210
250
790
450
25
20
25
10
Total
73,900
147.8 328.2
3,355 7,430
-------
Table 38. ESTIMATED SORGHUM CROP RUNOFF IN APRIL, MAY, AND JUNE (METHOD ONE)
N3
Ol
Annual runoff (in.)
Region
Northeast
Lake States
Corn Belt
Northern Plains
Appalachian
Southeast
Delta States
Southern Plains
Mountain
Pacific
Total
Acres (000)
.
-
1,100
8,000
400
300
600
8,800
1,200
300
20,700
Low
-
55
1
10
10
10
1
1
1
High
.
-
15
3
25
20
20
2
2
2
Spring
Spring acre-inches
runoff (%)
.
-
35
40
30
30
35
50
40
40
Low
-
1.9
3.2
1.2
0.9
2.1
4.4
0.5
0.1
14.3
runo f f ,
(millions)
High
-
5.8
9.6
3.0
1.8
4.2
8.8
1.0
0.2
34.4
Spring
(101
Low
-
43
72
27
20
48
100
11
2
323
runoff
0 Ib)
High
131
217
68
40
95
200
23
4
778
-------
MEAN TOTAL PRECIPITATION (Inches), APRIL
By State Climatic Divisions
Figure 14. Mean total precipitation (inches), April, by state climatic divisions.
Source: U.S. Department of Commerce, Climatic Atlas of the United States, p. 45 (1968),
-------
MEAN TOTAL PRECIPITATION (Inches), MAY
State Climatic Divisions
Figure 15. Mean total precipitation (inches), May, by state climatic divisions.
Source: U.S. Department of Commerce, Climatic Atlas of the United States, p. 46 (1968).
-------
MEAN TOTAL PRECIPITATION (Inches), JUNE
State Climatic Divisions
00
Figure 16. Mean total precipitation (inches), June, by state climatic divisions.
Source: U.S. Department of Commerce, Climatic Atlas of the United States, p. 46 (1968).
-------
For our estimation, the high value of the percent runoff on the
crops is assumed to be 30%. The low value is assumed to be below that of
continuous bluegrass, and is placed at 10%. These values place the limits
in a wide enough range to reduce the error of the estimation to a mini-
mum.
Tables 39 and 40 are constructed to show the estimated runoff from
the corn and sorghum crops using rainfall statistics and estimates of the
amount of runoff that accompanies the rainfall. Average rainfall over each
region is taken from Figures 14, 15, and 16.
Both Methods 1 and 2 use rather crude methods to estimate the run-
off quantities from the crops, but no other methods are available to make
more reasonable estimates that do not involve a massive research effort
which is outside the scope of this study. The values of the runoff esti-
mates just presented are compared in the next section.
Methods 1 and 2 Compared - The information developed by the two methods
for predicting the amount of runoff from corn and sorghum crops is now
compared. Table 41 compares the estimates developed by each method and
shows that the runoff values predicted by Method 2 are less than those
predicted by Method 1 for the corn crop, while the opposite is true for
the sorghum crop. This arises from the fact that in all regions except
the Southern and Northern plains, the amount of runoff is higher in
Method 1 than Method 2. These two regions show the opposite effect. Since
the acreage in these regions is insignificant in the corn crop, the total
values of runoff predicted by Method 1 are higher. However, in the sorghum
crop these two regions are dominant in sorghum production and make the
total runoff values higher for Method 2 than for Method 1.
The Northern and Southern plains deviate from the pattern since the
runoff in these two regions shown on the annual runoff map is very low
compared to the rest of the nation, while the spring rainfall is only
slightly lower in these two regions than in the others around the re-
mainder of the U.S. (particularly in May and June). Whether the runoff,
as a percentage of rainfall, is lower for the sorghum crop in these two
regions than in the other regions is indeterminate. Without further in-
formation, this conflict defies evaluation.
The two methods agree reasonably well considering the gross values
used in each method. The approach taken here to estimate runoff is diffi-
cult to improve upon unless a mountain of statistics is available to the
researcher who attempts to make such an estimate. Even then, variables
such as cropping practices and rainfall patterns constantly change, and
make calculations of runoff an estimation in the final analysis. This is
the reason a range of values has accompanied each estimation made to this
point.
129
-------
Table 39. ESTIMATED CORN CROP RUNOFF IN APRIL, MAY, AND JUNE (METHOD TOO)
I-1
U)
o
Rain, acre-inches
(millions)
Region
Northeast
Lake States
Corn Belt
Northern Plains
Appalachian
Southeast
Delta States
Southern Plains
Mountain
Pacific
Acres (000)
3,600
12,000
35,400
12,000
4,700
3,400
400
800
1,100
500
April
12
28
118
25
17
14
1
2
2
1
May
15
39
139
37
19
12
1
3
2
1
June
14
50
164
44
21
15
1
4
2
1
Pounds rain
(1010) .
April
270
630
2,670
570
380
320
20
50
50
20
May
340
880
3,140
840
430
270
20
70
50
20
June
320
1,130
3,710
1,000
480
340
20
90
50
20
Runoff (1010 Ib)
% Runoff
Low
10
10
10
10
10
10
10
10
10
10
High
30
30
30
30
30
30
30
30
30
30
April
Low
27
63
267
57
38
32
2
5
5
2
High
81
189
801
171
114
96
6
15
15
6
May
Low
34
88
314
64
43
27
2
7
5
2
High
102
264
942
252
129
81
6
21
15
6
June
Low
32
113
371
100
48
34
2
9
5
2
High
96
339
1,113
300
144
102
6
27
15
6
Total
73,900
220
268
316 4,980 6,060 7,160
498 1,494 606 1,818 716 2,148
-------
Table 40. ESTIMATED SORGHUM CROP RUNOFF IN APRIL, MAY, AND JUNE (METHOD TWO)
Rain,
acre-inches
Pounds rain
(millions) (1010)
Region
Northeast
Lake States
Corn Belt
Northern Plains
Appalachian
Southeast
Delta States
Southern Plains
Mountain
Pacific
Acres (000)
—
-
1,100
8,000
400
300
600
8,800
1,200
300
April
_
-
4
19
1.5
1.3
3.0
22
1.3
0.5
May
_
-
5
29
1.5
1.1
3.5
34
1.5
0.1
June
—
-
5
32
1.5
1.2
2.7
25
1.4
0.1
April
tm
-
90
430
30
30
70
500
30
10
May
—
-
110
660
30
30
80
770
30
2
June
_
-
110
720
40
30
60
570
30
2
% Runoff
Low
_
-
10
10
10
10
10
10
10
10
High
„
-
30
30
30
30
30
30
30
30
Runoff (1010 Ib)
April
Low
_
-
9
43
3
3
7
50
3
1
High
_
-
27
129
9
9
21
150
9
3
May
Low
^
•
11
66
3
3
8
77
3
-
High
—
-
33
198
9
9
24
231
9
1
June
Low
_
-
11
72
4
3
6
57
3
-
High
_
-
33
216
12
9
18
171
9
1
Total
20,700
52.6 75.7 69.0 1,190 1,712 1,562
119
357 171
514 156
469
-------
Table 41. COMPARISON OF METHODS 1 AND 2
Corn crop
Method 1 Method 2
spring
Region
spring runoff (1010 Ib) spring runoff (1010 Ib)
Low
180
500
1,970
110
320
230
15
10
15
5
High
430
1,220
4,210
250
790
450
25
20
25
10
Low
93
264
952
241
129
93
6
21
15
6
High
279
792
2,856
723
387
279
18
63
45
18
Northeast
Lake States
Corn Belt
Northern Plains
Appalachian
Southeast
Delta States
Southern Plains
Mountain
Pacific
Total 3,355 7,430 1,820 5,460
Sorghum croj)
Northeast - - -
Lake States - -
Corn Belt 43 131 31 93
Northern Plains 72 217 181 543
Appalachian 27 68 10 30
Southeast 20 40 9 27
Delta States 48 95 21 63
Southern Plains 100 200 184 552
Mountain 11 23 9 27
Pacific 2 4_ 1 5_
Total 323 778 446 1,340
132
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The next section brings all of the information previously developed
into practical application in estimating the quantities of pesticides
lost from the corn, sorghum, and apple crops in the year 1971.
Estimated Pesticide Losses from the U.S. Corn, Sorghums and Apple Crops
(1971) - Quantities
The previous discussions involving runoff and erosion should alert
the reader to the fact that the values used were estimates based on lim-
ited information. All of the studies performed on pesticide concentra-
tions in runoff and erosion events were conducted under limited circum-
stances and certainly cannot be taken as fact under all circumstances,,
The runoff predictions were based on average rainfall over a period of
25 years (1931 to 1955), and the percent of runoff accompanying the rain-
fall was predicted on average values for crop runoff. All of these esti-
mates must be considered rather gross and can only be considered esti-
mates.
These estimates, however, are not unrealistic since a range of values
is given with the realization that a singular value is impossible to ar-
rive at with confidence. No method exists today to accurately predict the
quantities of runoff and erosion experienced on such a diversified area
as the corn or sorghum crop. Since cropping practices vary widely, and
these practices have a significant effect on runoff and erosion, only an
intensive effort to gather pertinent data and statistics on the relevent
factors affecting the quantities of erosion and runoff in agriculture
would allow the accurate analysis of the problem dealt with here.
This points out an important fact. There is a great deal of inform-
ation on the concentrations of pesticides in soil and in water. However,
these facts are of little value in quantifying pesticide losses in run-
off and soil erosion from crops since there is no accurate method of quan-
tifying the amount of runoff and soil losses actually occurring over a
wide area. Any investigations into the problem of quantities of pesti-
cides lost from crops must determine the losses as a percentage of the
amount applied, since quantities of pesticides applied to crops are more
easily determined and documented than are amounts of runoff and erosion.
Some of the studies presented in Appendix B have done this and are valu-
able in our analysis. The vast array of statistics on concentrations in
soil and water are of little use in the type of analysis attempted here.
The approach of using concentrations was attempted to determine if
a reasonable estimate could be made, but apparently the quantification
of runoff and erosion is not now possible. Therefore, only estimates
based on the pesticides applied to the crops, using the second approach,
133
-------
are used. Data are more limited on the loss of pesticides as a percent-
age of the amount applied, but it is the only reasonable approach that
can be taken with the information currently available.
For the convenience of presentation, the estimates for pesticide
losses due to runoff and erosion from the U.S. corn, sorghum, and apple
crops (1971) are discussed in the following subsections: (a) herbicides;
(b) insecticides; (c) fungicides; and (d) other pesticides.
Herbicides - In 1971, herbicide use in apple orchards amounted to only
197,000 Ib active ingredient. The amount of herbicides used in orchards
was negligible compared to the amounts used on corn (101,060,000 Ib) and
sorghum (11,538,000 Ib). Therefore, runoff losses of herbicides from ap-
ple orchards are negligible, and only the corn and sorghum crops are
dealt with below.
The estimation for the amount of herbicide loss from the corn and
sorghum crops requires two types of information: (a) the percent herbi-
cide loss in runoff and soil erosion as a percent of the amount applied;
and (b) the amount of herbicide applied to the crop. The percent loss is
given in Table 36 (p.120) for five herbicides, and the amount of these
herbicides applied to the corn and sorghum crops in 1971 is given in Ap-
pendix C, Tables C-2 and C-6, and are listed below:
Amount applied to corn Amount applied to sorghum
Herbicide in 1971 (OOP Ib) in 1971 (OOP Ib)
Alachlor 8,360 20
Atrazine 52,000 4,175
2,4-D 9,144 2,039
Propachlor 21,300 1,433
Propazine 583 2,585
The percentage figures for the amount of herbicide loss in runoff
and soil erosion in Table 36 take into account the fact that losses are
high if runoff and erosion occur during first week after application.
The total herbicide loss as a percent of the amount applied will vary
with each crop, depending upon the extent to which runoff and erosion
occur in the first critical week after application. The chart below, by
calculating the total percent loss of herbicide assuming 20, 40 and 60%
of the crop has a runoff event in the first week after application, shows
how the percent herbicide loss will vary.
134
-------
Low
0.1
0.6
0.25
0.1
0.6
High
1.6
3.0
1.3
1.6
3.0
Low
0.2
0.7
0.45
0.2
0.7
High
2.2
4.0
2.3
2.2
4.0
Low
0.3
0.8
0.65
0.3
0.8
High
2.8
5.0
3.3
2.8
5.0
Percent of crop having a runoff event in first week
after application
20% 40% 60%
Percent herbicide loss in runoff and erosion as a
percent of amount applied
Herbicide
Alachlor
Atrazine
2,4-D
Propachlor
Propazine
The values given for 40% of the crop having a runoff event in the
first week after herbicide application are used to calculate the herbi-
cide loss in 1971 on the corn and sorghum crops, since no information was
found on this subject as to the actual percentage. If the 40% figure is
in error, that is, only 20% of the crop had runoff in the first critical
week, then the values estimated are high; and low, if the 60% figure is
correct.
Table 42 gives the estimates of the herbicide loss on the corn and
sorghum crops (1971) based on the information just presented. The percent-
age of the total herbicides applied to each crop is merely the amount of
each herbicide applied as a percent of the total amount applied--which
was 101,060,000 Ib on corn, and 11,538,000 Ib on sorghum.
This table represents the estimated amount of herbicides lost from
the two crops in 1971. More than 90% of the herbicides used on corn are
represented in Table 42, and the estimate shows that between 1/2 and 3
million pounds of those herbicides were lost due to runoff and erosion
that year. This represents a loss of 0.5 to 3.2% of the selected herbi-
cides (in Table 42) applied to corn. Almost 90% of the herbicides applied
to the sorghum crop are represented in Table 42, and the estimate shows
that between 60,000 and 350,000 Ib of these herbicides were lost due to
runoff and erosion that year. This represents a loss of 0.6 to 3.4% of
the selected herbicides in Table 42 applied to sorghum. At first glance,
3.2% may seem small, but on the corn crop this percentage represents
3 million pounds of herbicide lost into the environment.
To complete the estimation, the high-low percentages shown above are
used for the entire 1971 corn and sorghum crops since the percentages de-
termined above are based on approximately 90% of the total herbicide use
on the two crops that year. Extrapolating these figures to all of the
herbicides (1007o) used gives:
135
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Table 42. ESTIMATED LOSS OF SELECTED HERBICIDES IN RUNOFF AND SOIL EROSION FROM
THE U.S. CORN AND SORGHUM CROPS (1971)
Herbicide
Alachlor
Atrazine
2,4-D
Propachlor
Propazine
Alachlor
Atrazine
2,4-D
Propachlor
Propazine
Amount applied
(OOP Ib)
8,360
52,000
9,144
21,300
583
91,387
20
4,175
2,039
1,433
2,585
10,252
Corn
Total herbicides
used in corn
8.3
51.5
9.1
20.8
0.5
90.3
Sorghum
Lost
Low
0.2
0.7
0.5
0.2
0.7
0.2
0.7
0.5
0.2
0.7
00
High
2.2
4.0
2.3
2.2
4.0
2.2
4.0
2.3
2.2
4.0
Lost (OOP Ib)
Low
17
364
46
43
4
474
29
10
3
li
60
High
184
2,080
210
470
23
2,967
167
47
32
103
349
-------
Amount applied, 1971 Loss (%) Loss (OOP Ib)
Crop (OOP Ib) Low High Low High
Corn 101,060,000 0.5 3.2 500
Sorghum 11,538,000 0.6 3.4 70
These figures are the estimates for the herbicide losses from the U«S.
corn and sorghum crops (1971) due to runoff and soil erosion. As previ-
ously mentioned, the herbicide losses from apple orchards that year are
negligible.
Insecticides - Insecticides applied to the three crops amounted to: corn,
25,500,000 Ib; sorghum, 5,700,000 Ib; and apples, 4,830,000 Ib. The in-
formation developed in Section III shows that about 70% of the insecti-
cides applied to sorghum, and all of the insecticides applied to apples
are foliar applications, while over 90% of the insecticides used on corn
crops are soil applications. Since most of the insecticides used on sor-
ghum and apples are foliar applications, and the percentage losses of the
major insecticides used on these two crops (shown in Table 36) are insig-
nificant, the quantities of insecticides that are transported from the
sorghum and apple crops by runoff are considered to be negligible. There-
fore, only insecticides applied to the corn crops are considered in this
section.
The information developed in Table 36 (p. 120) concerning the per-
centage losses of some of the insecticides applied to the soil of corn
crops is correlated with the amount of insecticides applied to corn in
1971, as given in Appendix C, Table C-3, and the estimated loss of se-
lected insecticides in the runoff and soil erosion from the UoSo corn
crop (1971) is shown in Table 43 (assuming that 40% of the entire corn
crop received a runoff event in the first week after insecticide appli-
cation, as was assumed with herbicides in the previous section). This
table shows that between 44,000 and 184,000 Ib of the selected insecti-
cides applied to the soil of corn crops were lost due to runoff and ero-
sion, or from 0.3 to 1.370 of the selected insecticides considered.
Slightly more than half of the amount of insecticides used on corn
is represented in Table 43. Since the percentage losses are low, the as-
sumption is made that these percentages apply to the entire corn crop as
well, without introducing a significant error in the extrapolation. There-
fore, the estimates for losses of all insecticides used in corn are:
137
-------
oo
Table 43. ESTIMATED LOSS OF SELECTED INSECTICIDES IN RUNOFF
AND SOIL EROSION FROM THE U.S. CORN CROP (1971)
Insecticide
Aldrin
Carbofuran
Diazinon
Parathion
Total
Amount applied
(000 Ib)
7,759
2,681
1,991
1,329
13,760
Total insecticides-'
used in corn (%)
30.4
10.5
7.8
5.2
53.9
Lost (%) Lost (000 Ib)
Low High Low
0.5 2.0 39
0.2 1.0 5
Negl. 0.04 0
0.01 0.1 0
44
High
155
27
1
1
184
a/ Amount of each insecticide applied as a percent of the total insecticides applied
(25,531,000 Ib) to corn in 1971.
-------
Amount applied, 1971 Loss (%) Loss (OOP Ib)
(OOP Ib) Low High Low High
25,531,000 0.3 1.3 80 330
These figures represent the insecticide losses from the entire U.S. corn
crop (1971) due to runoff and soil erosion. As previously mentioned, the
insecticide losses from sorghum and apples that year are negligible.
Fungicides - Fungicides used in 1971 on corn and sorghum were not speci-
fied by the U.S. Department of Agriculture report..!?./ This report showed
that a total of 1,732,000 Ib of fungicides (excluding sulfur) were used
on the category of crops which included corn, wheat, sorghum, rice, to-
bacco, soybeans, alfalfa, and sugarbeets, as well as other grains and
field crops. Obviously, the use of fungicides on corn and sorghum (com-
pared to herbicide and insecticide usages) was very small, and any losses
of fungicides due to runoff and erosion from corn and sorghum are negli-
gible.
Conversely, apples were treated with 7,207,000 Ib of fungicides
(excluding sulfur). In this case, however, fungicides are applied to the
trees and apples, and not to the soil. Since fungicide applications in
apple orchards are foliar, little loss from runoff and soil erosion will
occur, and the quantities of fungicides that do reach the soil, and sub-
sequently, runoff the orchard, are negligible.
Other Pesticides - The broad category of "other pesticides" includes mit-
icides, fumigants, defoliants, desiccants, rodenticides, plant growth
regulators, and repellents. Each of the three study crops received treat-
ment by several of these miscellaneous pesticides, but the quantities in-
volved were small.
Corn was treated with 443,000 Ib of miscellaneous pesticides (Appen-
dix C, Table C-4). Fumigants accounted for 386,000 Ib of pesticides, and
miticides accounted for the remaining 57,000 Ib. These quantities are
small compared to the insecticides and herbicides used on corn, and losses
of these pesticides are negligible.
Sorghum was included in a broad category of crops--the same one men-
tioned previously under fungicides, excluding corn—that were treated with
3,334,000 Ib of miscellaneous pesticides..!!/ Fumigants accounted for
3,124,000 Ib, or over 90% of the total applied. Again, the use of miscel-
laneous pesticides on sorghum is considered negligible, and the losses
of these pesticides are negligible, also.
139
-------
Apples were treated with 548,000 Ib of miscellaneous pesticides (Ap-
pendix C, Table C-ll). Miticides accounted for 387,000 Ib and plant growth
regulators, for 174,000 Ib. Miticides are primarily foliarly applied, and
do not represent a large quantity of pesticides subject to transport from
the orchards by runoff and erosion. Any losses of these pesticides in this
manner are negligible.
The next section discusses two miscellaneous discharges of pesticides
into the environment; pesticide spills and pesticide disposal.
MISCELLANEOUS PESTICIDE DISCHARGES
Pesticide spills and pesticide disposal both contribute to the inef-
ficient use of agricultural pesticides. Spills are primarily accidental
and occur randomly in the use of agricultural pesticides, just as acci-
dents occur randomly in all other areas of life. Though spills are inef-
ficient and potentially dangerous in some cases, they represent a negligi-
ble loss when considering the amounts of pesticides used annually to treat
crops. Disposal involves both pesticide containers and pesticide residues
remaining in the applicator after crop treatment has taken place. Disposal
is required in all pesticide operations and the amount of pesticides which
are disposed of as residues in both containers and applicators is substan-
tial. However, disposal techniques are controllable since the methods used
to dispose of pesticides are the device of man himself. Proper disposal
techniques result from education and recognition of the importance good
techniques have in keeping the environment clean. Any inefficiencies prac-
ticed today in agricultural pesticide disposal can be substantially re-
duced tomorrow with an effort to disseminate the proper information.
Since spills involve negligible amounts of pesticides and disposal
is within man's immediate control, these two subjects did not receive
detailed attention in this study. For the sake of completeness, however,
these subjects do deserve mention, and are briefly discussed below.
Pesticide Spills
The subject of spillage is covered in this report primarily for the
sake of completeness. Spills can occur during handling, loading, or ap-
plication of pesticides. However, spills are usually accidental and are
not considered a wasteful practice unless they involve intentional dump-
ing or avoidable negligence. A brief look at this problem will help to
show that it is insignificant in relation to other routes of waste.
140
-------
Spills can occur in various ways. One way is discharge of the pes-
ticide from a broken, punctured, or defective container. This is gen-
erally accidental and not inherently avoidable. Another way is faulty
removal of the pesticide from the container to load the pesticide into
a mixing tank or into the hopper of the applicator. Again, any spills at
this time will be accidental with the exception of excessive drift of
dust from granular formulations. Since most pesticides are toxic, common
sense dictates that care be exercised to prevent escape of pesticide
quantities that could harm the operator during loading. Even in isolated
instances where this occurs, the problem is negligible in comparison to
the problems of drift that may occur during application.
A third type of spill can occur when loading the spray tanks of an
airplane from the nurse tank. The pesticide is transferred by use of an
umbilical hose connection, which has check valves on the ends. As long
as these hoses are maintained properly there is no leakage. A fourth type
of spill may occur when there is leakage from the applicator due to faulty
tank valves, lines, or connections. Pesticide losses from these sources
do occur, but they will be corrected as soon as they are discovered since
pesticides cost money and are toxic substances. A fifth type of spill is
one in which the applicator is outside the target area and the operator
accidentally or erroneously releases pesticides. This may be considered
a spill, but it would obviously be done accidentally or unintentionally.
The examples cited above show the relative insignificance of this
route of loss compared to the other factors considered in this report.
Pesticide Disposal
The disposal of pesticides in agriculture has two separate aspects:
1. Disposal of pesticide containers; and
2. Disposal of unused pesticide remaining in the application equip-
ment.
In either case, the original container, tank, or hopper may be empty or
partially full. The most serious problem with respect to the quantity of
pesticide involved is disposal of surplus spray solutions in the partially
full tank or hopper.
141
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The disposal method employed for empty pesticide containers is most
often dictated by container size. Most pesticides are sold in bags, 5-gal.
cans (metal and plastic), and 55-gal. drums. Approximately 70% of emulsi-
fiable concentrate formulations sold are packaged in 1- and 5-gal. contain-
ers, 15% in 30-gal. containers, and 15% in 55-gal. drums; all wettable pow-
der formulations are marketed in bag-weights of 50 Ib or less; and granular
formulations are packaged in bags weighing 80 Ib or less.—' Due to their
size, most 55-gal. drums and a large number of the 30-gal. containers are
recycled or disposed of by a commercial disposal service. The remaining
containers, approximately 85%, are disposed of by the farmer,* due to the
combined factors of smaller container size and inaccessibility of an estab-
lished disposal site. Disposal of dry formulation containers is usually
handled on site. Most commonly, the empty bags are simply thrown in the
trash, or burned and the remains taken to a dump site or an approved land-
fill. Metal and plastic containers are generally rinsed and the rinses
added to the spray solution. This procedure aids in reducing not only po-
tentially dangerous residues that may remain in the container but also
minimizes the amounts of pesticide that may be lost if the containers
were discarded without rinsing. Disposal of these small metal, plastic,
and glass containers may follow two routes: (a) the containers may be
burned and the remains taken to a dump or landfill; or (b) the containers
may be crushed and buried at a site where exposure to man and animals and
possible contamination of water supplies is minimal. 14-1!5/
Empty containers accumulated from small farm operations are most
often small, single-trip containers which may be disposed of by the farm-
er. Disposal of metal, plastic, and glass containers is generally by the
rinse/crush/bury method described above. "Empty" bags are usually thrown
in the trash, buried, or burned. (It should be noted that special care
must be taken not to inhale fumes from open burning of "empty" contain-
ers.)I6/
Disposal problems encountered by professional applicators are very
similar to those of the large agricultural user in that a large number of
empty containers are associated with such operations. Often, "empty" con-
tainers tend to build up along runways or in areas where pesticide mix-
ing occurs. Empty 55- and 30-gal. drums are returned to the supplier, taken
to community-operated burial landfill sites, or buried on privately owned
premises. Disposal procedures employed for small metal, plastic, and glass
containers in addition to paper bags parallel those utilized by small farm
operations.
* MRI estimate based on package-size data.
142
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The second aspect of disposal of pesticides in agriculture—emptying
the application equipment--has two facets: (a) disposal of the surplus
pesticide mixture which may be left in the tank or hopper; and (b) clean-
ing the empty equipment. The primary disposal problem in agriculture, in
terms of quantity, is that of the surplus spray solution. The disposal
recommendations for surplus solutions are as follows. Whenever possible,
dilute spray solutions should be "carefully applied to the area that has
been treated, adjacent borders or safe, protected waste areas. Extreme
care must be exercised so that the extra pesticide applied will not re-
sult in phytotoxicity, over-tolerance residues or other undesirable re-
sults." However, if this method is not feasible, the surplus solution
should be run into a shallow holding pit dug in an area where the hazards
of percolation or runoff are minimal. ? /
Manufacturers recommend cleaning the equipment after each use, or
at the end of the day, making disposal of clean-out rinse solutions a fre-
quent problem. Rinse solutions may be applied along with the surplus spray
solutions to the previously treated area, adjacent borders, or protected
waste area; or may be added to the holding pit with the surplus pesticide
solutions. Alternatively, many professional applicators and large farm
operators construct sumps (which meet EPA specifications) in which clean-
out rinses are placed.
Quantification of pesticides "wasted" in surplus spray solutions,
empty containers, and clean-out rinses is not feasible. Disposal of pes-
ticides in cleaning operations is inherent and unavoidable in the agri-
cultural process and, therefore, is not a wasteful practice. Whenever
possible, pesticide containers are rinsed several times and the rinses
added to the spray solution to minimize pesticide loss. Likewise, resi-
dues remaining in paper bags are negligible when compared to pesticide
loss via drift, runoff, overapplication, etc. Finally, application equip-
ment operators attempt to accurately calculate the amount of spray solu-
tion required for effective treatment. Surplus spray solutions are eco-
nomic inputs which do not achieve their purpose, i.e., effective pest
control. Consequently, losses of pesticides by this route are held to a
minimum by economic incentives.
143
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REFERENCES TO SECTION IV
1. Meyer, L. D., and W. H. Wischmeier, "Mathematical Simulation of the
Process of Soil Erosion by Water," paper presented at the 1968
Winter Meeting of the American Society of Agricultural Engineers,
Chicago, Illinois, 10-13 December 1968.
2. Meyer, L. D., and J. V. Mannering, "Tillage and Land Modification
for Water Erosion Control," in Tillage for Greater Crop Produc-
tion, American Society of Agricultural Engineers, Proceedings,
168, pp. 58-62, St. Joseph, Michigan (1968).
3. Wischmeier, W. H., and D. D. Smith, "A Universal Soil Loss Equation
to Guide Conservation Farm Planning," Seventh International Con-
gress of Soil Science, Madison, Wisconsin (1960).
4. "Procedure for Computing Sheet and Rill Erosion on Project Areas,"
Technical Release No. 51, Soil Conservation Service, U.S. Depart-
ment of Agriculture (1972).
5. "Agricultural Pollution of the Great Lakes Basin," report by Canada
and the United States, U.S. Environmental Protection Agency, Water
Quality Office (1971).
6. Lin, S., "Nonpoint Rural Sources of Water Pollution," State of
Illinois, Circular No. ISWS-72-C1R111; Department of Registration
and Education, Illinois State Water Survey Urbana (1972).
7. U.S. Geological Survey, National Atlas of the United States of
America, Washington, D.C. (1970).
8. Kearney, P. C., and C. S. Helling, "Reactions of Pesticides in Soils,"
Residue Reviews, 25 (1969).
9. Pesticide Manual, Second Edition, British Crop Protection Council
(1971).
10. U.S. Department of Agriculture, Water; The Yearbook of Agriculture,
1955. Washington, D.C. (1955).
11. U.S. Department of Commerce, Climatic Atlas of the United States
(1968).
12. U.S. Department of Agriculture, "Farmers' Use of Pesticides in
1971 . . . Quantities," Agricultural Economic Report No. 252,
Economic Research Service, Washington, D.C. (1974b).
144
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13. Lawless, E. W., R. von Rumker, and T. L. Ferguson, "The Pollution
Potential in Pesticide Manufacturing," prepared for the U.S» En-
vironmental Protection Agency, Technical Studies Report TS-00-72-
04, p. 213, June 1972.
14. "Summary of Interim Guidelines for Disposal of Surplus or Waste
Pesticides and Pesticide Containers," Working Group of Pesticides
Report WGP-DS-1, National Technical Information Service, AD 720
391, December 1970.
15. Lawless, E. W., T. L. Ferguson, and A. F. Meiners, "Guidelines for
the Disposal of Small Quantities of Unused Pesticides," prepared
for the U.S. Environmental Protection Agency, Contract No. 68-01-
0098 (1974).
16. Ferguson, T. L., "Pollution Control Technology for Pesticide Form-
ulators and Packagers," prepared for the Environmental Protection
Agency, Environmental Protection Technology Series, EPA-660/2-74-
094, January 1975.
145
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APPENDIX A
FIELD STUDIES ON PESTICIDE DRIFT DURING APPLICATION
147
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As a result of a review of the literature, a number of field studies
on pesticide drift were obtained which are representative of attempts to
assess the effects on drift from the type of equipment, type of formula-
tion, and techniques used in agriculture. These studies are listed below
in the order they appear in this appendix.
1. Aerial application - drift;
2. Aerial application - time of application and drift;
3. Aerial application - low volume versus ultra low volume sprays;
4. Aerial application - low volume versus ultra low volume sprays;
5. Aerial application - dilute versus low volume sprays;
6. Aerial application and mist-blower application compared;
7. Aerial application and ground application compared;
8. Ground application - effects of an additive, nozzle pressure,
and evaporation on drift; and
9. Ground application - spray drift in treating orchards.
A brief discussion and the important findings of each study are given
below. The references used to obtain these studies appear at the conclu-
sion of this appendix.
AERIAL APPLICATION - DRIFT
Research has been conducted by Wesley E. Yates and Norman B. Akesson
at the University of California, Davis, for over a decade to determine
the amount of drift involved in various types of spray applications. They
have studied drift of dusts and sprays under actual operating conditions.
Tests—' conducted over a period of years have included comparisons
of the relative quantities of drift for ground applications and aerial
applications; for low volume and ultra low volume applications; for large
particles and small particles; and for various climatic conditions. The
general relationships these factors have to each other, depending on var-
ious circumstances are:
148
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• Aerial applications show a higher potential for drift than ground
applications when spraying similar droplet sizes.
» Ultra low volume sprays are usually applied as smaller particles
than low volume sprays and are generally more susceptible to
drift.
• Particle size definitely affects the drift potential of sprays
and solids as well. Smaller particles are highly subject to drift
at sizes below 50 p,.
• Stable atmospheric conditions produce fewer total quantities of
particle drift than unstable conditions.
Though these conclusions are basic and seemingly self-evident, they pro-
vide good guidelines to show some of the factors which must be considered
if drift is to be minimized.
Akesson and Yates have found much more detailed information than
that presented above, but to include all of their findings in this report
would require a great deal of space. The results of their work in deter-
mining spray drift from aircraft is best summarized by presentation in
a table they have constructed to show the estimated amounts of drift that
accompany aerial applications. Table A-L?./ represents the knowledge and
experience they have on the subject of drift in aerial spray applications,
and gives a good overview of the problem dealt with in this study.
G. W. Ware et al., have also conducted a number of drift tests at
the University of Arizona, Tuscon. They examined the effects of several
variables, including formulation, thickeners, temperature, time of appli-
cation, and gallons of spray per acre, that affected the percent of pes-
ticide deposited on-target from aerial spray applications. A summary of
a number of tests conducted over a period of time is given in Table A-2._'
Table A-2 shows that over a long period involving a number of vari-
ables and different conditions, the average on-target deposit of aerially
applied pesticides was about 50%. Dust had the lowest deposit in the tar-
get area by far—only 14%. The spray deposits varied from 28 to 737o, de-
pending on the variables involved. This table is a good indication that
aerial spraying is subject to wide variations in drift losses, and, on
the average, pesticides sprayed from aircraft have only a 50% chance of
reaching their intended target.
149
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Table A-L AIRCRAFT SPRAY DROP SIZE RANGE, USE AND APPROXIMATE RECOVERIES
Spray
Coarsi
Cone i
roti
description atomizer
> aerosols
ind fan nozzles, and
jry atomizers
Atomizer example^'
80,005 down
D2-13 down
200-300 lb/ln2
Drop size range .
(microns iun'VMD)2'
< 125
Percent estimated
depoalt in 1,000 ft£/
< 25
General use
For serosol applications, vector
control and forest Insects. Agri-
cultural pathogens, low volume
rates, primarily adultlcldlng use.
Fine spraya
Cone and fan nozzlea, and
rotary atomizers
Medium sprays
Cone and fan nozzlea, and
rotary atomizers
Coarae sprays
Cone and fan nozzlea
Spray additives
80,005 down
D6-45 down
50-100 lb/in
2
D6-46 down
30-50 lb/in2
D6-46 back
30-50 lb/ln2
100-300
40-80
300-400
400-600 with
additives up
to 2,000
70-90
85-98
Primarily for forest pesticide
chemicals and large area vector
control with low dosages of low
toxlclty and rapid degradation
chemicals. Also for agricultural
Insect pathogens.
Commonly used spray drop size for
all low toxlcity agricultural chemi-
cals where good coverage is neces-
sary.
Recommended for toxic pesticides of
restricted classification where
thorough plant coverage is not
essential.
Minimum drift spraya
Jet nozzles
Spray additives
Maximum drift control
Low turbulence nozzlea
D4 to D8 down at
less than 60 mph.
Back at over 60
mph. 30-50 lb/ln2
Micro foil®
Leaa than 60 mph
airstream
800-1,000 with
additives up
to 5,000
800-1,000
95-98
99.-t
Recommended for all toxic, re-
stricted class herbicides such as
phenoxy-aclda and others within
limitations of growing season and
nearness to susceptible crops.
Actual drift tests show one-fourth
the drift residue levels at 500 ft
downwind from the Mlcrofoll® com-
pared with the 04 to 08 jets used
with restricted nonvolatile herbi-
cides, phenoxy-aclds and others In
the area of susceptible crops, but
subject to limitations of growing
season and crop.
a/ Numbers refer to Spraying Systems Company, nozzles, down or back refer to position on aircraft boom.
b/ Drop size as determined with water base spraya, oils would give smaller drops.
£/ Deposit estimated in 1,000 ft downwind. Weather conditions: wind velocity 3-5 mph, neutral temperature, gradient.
Material released under 10 ft height.
Source: Akesson, N. B., and W. E. Yates, "Physical Parameters Relating to Pesticide Application," p. 29, paper supplied
by N. B. Akesson (1974).
150
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Table A-2. PERCENTAGE ON-TARGET DEPOSIT OF AERIALLY APPLIED INSECTICIDES
Insecticide
(Al/acre)
Toxaphene 4.0
Toxaphene 4.0
Methoxychlor
Methoxychlor
Methoxychlor
Methoxychlor
Methoxychlor
Methoxychlor
Methoxychlor
Methoxychlor
Methoxychlor
Methoxychlor
Methoxychlor
Methoxychlor
Methoxychlor
Methoxychlor
Methoxychlor
1.75
1.75
1.75
1.75
1.72
1.72
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
Time of
application
6:10 PM
6:10 PM
9:20 AM
9:20 AM
8:15 AM
8:15 AM
5:54 AM
4:00 PM
8:20 PM
8:20 PM
6:15 PM
7:00 PM
5:30 PM
4:50 PM
5:50 PM
3:00 PM
3:00 PM
Gallon
spray/acre
157. dust
5.7
8
8
7
7
7
7
8
8
5
5
5
5
5
5
5
Spray Temperature
thickener (°F)
61
- 61
Yes-' 93
93
36
Yes-' 36
60-70
95-100
83-86
83-86
Yes- 90-94
87-93
98-103
Yes- 100-105
Yes-' 99-103
103-105
103-105
Relative Wind
humidity (7.) (mph)
55
55
-
-
-
-
-
-
-
-
35
45
44
19
25
28
28
3-4
3-4
4.9
4.9
1.4-2.6
1.4-2.6
1-2.5
2-3.5
< 1.0
< 1.0
4.5-5.5
1.8-2.0
2.9-3.7
5-5.6
2-3
1.8-2.7
1.8-2.7
Sample
height (in.)
^
-
18
18
10
10
18
18
ground
24
12
12
12
12
12
12
12
Actual 7.
deposited
14.0
47.7
34.4
38.3
69.5
73.0
28.0
44.0
33.7
69.2
40.4
38.4
72.0
61.3
28.0
32.8
35.8
Correc ted
7. deposited
14.0
47.7
39.3
43.8
96.5
107.0
35.4
53.7
35.4
72.8
40.4
39.7
72.0
61.3
28.0
44.2
36.0
Average
46.7
53.3
a/ Spray thickener employed was carboxymethyl-cellulose.
b/ Spray thickener employed was Dacagln 0.87. (w/w).
e/ Spray thickener employed was molasses (247. V/V).
d/ Spray thickener employed was Cab-0-Sil (3.57. w/w).
-------
AERIAL APPLICATION - TIME OF APPLICATION AND DRIFT
The objective of this study, conducted by Ware et al. (1972),V
was to determine effects on target deposit and drift when pesticides
were applied at a rate of three times daily under different meteorologi-
cal conditions. Methoxychlor with a fluorescent tracer was applied aeri-
ally at a rate of 0.46 Ib/acre from a height of 5 to 6 ft at 90 mph using
28 Delavan D-2 floodtip nozzles. Applications were made at 6 a.m. (I),
3 p.m. (II), and 6:50 p.m. (Ill); all under a 2 to 3°F temperature in-
version. The dispersion of the pesticide was determined by analysis of
horizontal vertical collection cards placed 18 in. above ground level
in both the target area and at distances of 82, 165, 330, 660, and 1,320
ft downwind, and by analysis of 10, 1-ft2, alfalfa samples. Pertinent
meteorological data and target deposit and drift of the pesticide for
the three applications are shown in Table A-3.
On the basis of these tests it was concluded that early morning ap-
plication resulted in greater insecticide deposit in the target area.
However, downwind drift deposit beyond 660 ft was increased. The rela-
tively greater deposit of the early morning application is probably due
to a mild temperature inversion in conjunction with lower temperature
and higher relative humidity that reduced evaporation from spray drop-
lets.
AERIAL APPLICATION - LOW VOLUME VERSUS ULTRA LOW VOLUME SPRAYS
Brazzel et al. (1968)^./ conducted a study in which several pesti-
cides were applied aerially using two methods, ULV and diluted EC, to de-
termine the effect of formulation on the amount of drift. ULV formulations
(which are typically applied in amounts of 1/2 pt to 1/2 gal. active in-
gredient per acre) were applied with an EC boom (D-8 orifices and No. 45
Core) at rates of 1 to 1/2 gal. liquid per acre. EC formulations (which
are water diluted and typically applied in volumes of 1 to 10 gal/acre)
were applied with the same boom, but with 80015 nozzles and a Micronair®
atomizer, at rates of 1.5 gal/acre. EC and ULV sprays were each applied
at 5 and 20 ft flight heights under conditions in which the wind speed
ranged from 2 to 14 mph. The deposit efficiency of the pesticides was de-
termined in a 100 ft target area.
The results of this field study were as follows:
1. Application at a 20 ft flight height resulted in greater drift
and less deposit in the target area for both formulations.
2. Overall environmental contamination with ULV was less than with
EC applications.
152
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Table A-3. TIME OF APPLICATION VERSUS TARGET DEPOSIT AND DRIFT
Ui
OJ
Time of
application
6:00 a.m.
3:00 p.m.
6:50 p.m.
Relative
0-ft
69%
28%
28%
humidity
8-ft
66%
34%
42%
Wind (at 8 ft) Temperature
speed direction 8-ft 32-ft
1.5 raph
3 . 6 mph
3.2 mph
S 79°F
W 101°F
NW 99 °F
82°F
103 °F
101°F
Target
deposit
75.4%
63 . 3%
54.7%
Drift
24.6%
36.7%
45 . 3%
-------
3. The greater efficiency of ULV applications appeared to be due
to less evaporation from the droplets. ULV formulations require dispersal
as very small droplets to achieve adequate coverage and to avoid phyto-
toxicity. The droplets dispersed in the 100 to 150 p, range remained heavy
enough to fall to the ground in the target area. On the other hand, EC
droplets, although initially large, rapidly lost size and weight due to
evaporation of the water and became more subject to drift.
4. Tests showed that: "as droplet size increased, percentage re-
covery in the target area increased, but droplet count decreased. Drop-
let counts were usually higher with EC, but percentage recovery was lower
than for ULV. These results indicate a considerable increase in efficiency
of application to a specific target area with an increase in droplet sizes
from 100 to 150 p,. However, this increase is accompanied by a decrease in
coverage in the target area. Also, these results indicate a reduction in
drift, since more of the pesticide reached the target area."
5. A summary of the data obtained for the 12 field tests is given
in the following table (Table A-4).
AERIAL APPLICATION - LOW VOLUME VERSUS ULTRA LOW VOLUME SPRAYS
This field test was conducted by Adair et al. (1971)£/ to determine
the effect of formulation on drift under similar application conditions.
Methyl parathion was applied in two formulations. A 4 Ib/gal emulsifiable
concentrate (EC) formulation, applied both as an undiluted ULV spray and
a water-diluted (low volume) spray (2 gal/acre). Both formulations were
applied aerially at 80 mph and a height of 5 ft. ULV applications were
made with 12 No. 80015 nozzles at the rate of 1 Ib/acre, and with 24 No.
80015 nozzles at the rate of 2 Ib/acre. LV applications were made by 12
D-8 tip and No. 45 core disc-type cone spray nozzles at the rate of 1 lb/
acre.
Ground impaction sheets, oil-sensitive cards, and Casella® cascade
impactors (placed 5 ft above ground level) were used to determine the
amount of methyl parathion deposited in the target area, at distances of
10 and 20 ft upwind, and at distances up to 1/2 mile downwind. The ground
impaction sheets and oil-sensitive cards were collected 20 rain after pes-
ticide application; cascade impactors at 100, 330, 660, 1,320, and 2,640
ft downwind were operated 2, 5, 7, 10, and 15 min, respectively, after
application and were removed 30 min after sampling ceased.
The results of these tests were as follows:
1. Analysis of oil-sensitive cards indicated that the larger drops
fell to the ground in the flight path and that drops impacting away from
target area decrease in size as distance from the target area increases.
154
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Table A-4. PERCENTAGE PESTICIDE RECOVERY IN A 100-FT TARGET AREA
Formulation
ULV
ULV
EC
EC
ULV
ULV
EC
EC
ULV
ULV
ULV
ULV
Application
height (ft)
20
5
20
5
20
5
20
5
20
5
20
5
Application
system
ULV boom
EC boom
ULV boom
EC boom
ULV boom
Microns ir®
22.5°
Wind
(mph)
2
2
3
4
10
11
12
14
10
11
6
8
Target
recovery (%)
44.33
47.90
11.51
14.97
4.48
10.26
1.27
5.91
16.00
28.67
1.04
17.96
155
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The analysis also showed that 70 y, sized droplets could drift up to 1/2
mile downwind.
2. Airborne drift at a 5-ft height, as determined using the cascade
impactors, showed that drift was greater from ULV applications than from
LV applications. In addition, the amount of airborne drift at the 5-ft
height quickly stabilized in LV applications while airborne ULV drift was
high at 100-ft downwind, gradually decreasing as downwind distance in-
creased.
3. LV sprays were deposited in the narrow target area with more ef-
ficiency, but since relatively less was deposited downwind, a large quan-
tity must be quickly airborne. This may be due to water evaporating from
the initial droplet leaving a very small droplet which remains airborne.
4. Table A-5 shows the average percent recovery of methyl parathion
on the ground impaction sheets, both in the target area and at distances
of up to 1/2 mile. These data show that ground downwind deposit of methyl
parathion was greater from ULV applications than from LV applications.
5. The previous table shows that a 40-ft swath for LV and 80-ft
swath for ULV gave similar deposition in the target area, but more pes-
ticide impacted on the ground downwind using the ULV spray.
AERIAL APPLICATION - DILUTE VERSUS LOW VOLUME SPRAYS
Low volume application of pesticides requires atomization into fine
droplets which results in an increased drift hazard. A field study was
performed by R. J. Argauer et al.,Z' to compare deposits of malathion and
azinphosmethyl when aerially applied as LV (low volume) and water-diluted
emulsifiable concentrates. Tests were performed under adverse climatologi-
cal conditions to determine maximum possible drift.
Pesticide applications were made aerially at 100 mph at heights of
8 and 30 ft. LV applications of malathion and azinphosmethyl were made
using the undiluted technical formulations. Water was added to the tech-
nical formulations when applying the dilute sprays. Azinphosmethyl was
applied at a rate of 0.5 Ib active ingredient per acre and malathion at
2.0 Ib active ingredient per acre, active ingredient constant regard-
less of formulation. LV applications were made using a No. 8002 flat
spray nozzle directed 45 degrees forward and down into the airstream;
water-diluted spray applications were made with a No. D10-45 hollow-cone
nozzle directed straight down into the airstream. Mass median diameter
of the droplets in each case was approximately 220 p,.
156
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Table A-5. PERCENT RECOVERY OF METHYL PARATHION ON GROUND IMPACTION SHEETS
Formulation Average % recovery
and pound active Target ; Downwind
ingredient per acre Swath width area 40 60 80 100 330 660 1320 Total % Drift
M ULV 1.0 Ib/acre 40 ft 15.7 9.6 6.6 6.9 3.9 1.10 .10 .03 43.9 56.1
*-"
ULV 2.0 Ib/acre 40 ft 16.2 14.5 4.8 2.5 2.3 .60 .10 .05 41.0 59.0
ULV 1.0 Ib/acre 80 ft 31.7 — 9.6 5.0 4.6 1.20 .20 .10 52.4 47.6
LV 1.0 Ib/acre 40 ft 32.8 6.0 3.5 1.9 0.7 .60 .04 .02 45.5 54.5
-------
Relative spray deposits were determined by: (a) analysis of glass-
fiber filter discs attached to aluminum plates placed perpendicular to
the flight line and parallel to the wind direction; and (b) laboratory
bioassay of open Petri dishes placed near each collection plate. The
relative amounts of airborne azinphosmethyl 6 ft above ground at 200 and
2,000 ft downwind of the application line were determined using two
Staplex®high volume air samplers. Filter discs from the azinphosmethyl
test were analyzed by a fluorometric method; filter discs collected after
the malathion test were analyzed by gas chromatography. Bioassays of the
Petri dishes were performed by placing 1 to 7-day-old adult Drosophila
melanogaster in each dish; dishes were examined and records of fly mor-
tality were kept.
Pesticide amounts recovered were estimated by adding the amount re-
covered in the swath path to the amount recovered immediately downwind.
Estimated recoveries for azinphosmethyl and malathion applications at two
flight heights are shown in Table A-6.
Recovery of the diluted applications ranged from 46 to 96% of total
pesticide applied; average recovery for the three tests was 717<>. Recovery
from the undiluted low volume tests ranged from 18 to 62%, with the aver-
age recovery for the four tests 37.5%. In addition, it was determined
that more pesticide was recovered when applied from the 30 ft flight
height than when applied from the 8 ft flight height. It was postulated
that the lower pesticide recovery from the lower application height may
be due to severe turbulence caused by the aircraft slipstream reflected
by a swirling pesticide deposit pattern in the swath area. At the higher
flight pattern, however, drift to adjacent areas was more pronounced due
to an increased influence from crosswinds.
AERIAL APPLICATION AND MIST-BLOWER APPLICATION COMPARED
Ware et al»,—' conducted a study exploring pesticide drift differ-
ences between aerial and tractor-drawn mist blower applications. Aerial
and mist-blower (ground) applications to alfalfa fields were made simul-
taneously in late afternoon. Pertinent meteorological and application
data are shown in Table A-7.
Downwind drift contamination was determined by three techniques:
(a) analyses of alfalfa samples collected along two drift lines and at
165, 330, 660, 1,320, and 2,640 ft downwind; (b) air scrubbers (operated
66 min for mist applications and 28 min for aerial applications) sta-
tioned at four positions, 165 and 330 ft downwind; and (c) glass plates
(10 x 25 cm) placed 10 in. above ground at target site and at 165, 330,
660, and 1,320 ft downwind along both drift lines.
158
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vo
Table A-6. ESTIMATED PERCENTAGE SPRAY RECOVERY IN
THE SWATH ZONE TO 0.375 MILES DOWNWIND
Undiluted, technical formulation
8 ft application 30 ft application
Pesticide height height
Azinphosmethyl
0.5 Ib/acre
18%
62%
Diluted, aqueous formulation
8 ft application
height
46%
30 ft application
height
Malathion
2.0 Ib/acre
31%
39%
71%
96%
Table A-7. APPLICATION DATA: AFTERNOON APPLICATION OF METHOXYCHLOR
FROM BOTH A MIST BLOWER AND AIRCRAFT
Application Time of
method application
Mist blower 4:30 p.m.
Aerial 4:30 p.m.
Wind direction
and velocity
W-SW
3.0-5.0 mph
W-SW
3.0-5.0 mph
Application
Temperature speed
8 ft:
33 ft:
8
33
ft:
ft:
80 °F 4 mph
75°F
80°F 80 mph
75°F
Nozzle
and
25
Remite®
50
D-8 tip,
pressure
size
psi
slot-type
psi
No. 45
core
-------
All three techniques showed that downwind drift was greater from
mist-blower ground application than from aerial applications. "Alfalfa
1/2 mile downwind from the mist blower bore 0.27 ppm [pesticide], with
only 0.14 ppm from aerial application." Greater drift from mist-blower
applications was also confirmed by analyses of data from the glass plates
and air scrubbers.
Droplet size was determined by using microscope slides (1x3 in.)
placed 10 in. above ground in the target area and at 1,320 ft downwind;
slides were collected 30 min after completion of application and droplet
spread-diameter determined. Results indicated the mist blower had an
average droplet size of 100 p, in the target area and 18 p, at 1,320 ft
downwind. Average droplet size in the target area and 1,320 ft downwind
was 140 and 34 u,, respectively, for the aerial application.
Thus, each drift measurement technique indicated greater downwind
drift to 1/2 mile occurred during mist-blower application than during
aerial application. Ware et al. postulated that this was due to mist-
blower applications having a smaller droplet size and higher droplet in-
itial velocity (often in excess of 90 mph) both of which contribute to
a greater drift hazard.
AERIAL APPLICATION AND GROUND APPLICATION COMPARED
Ware et al.,—' conducted a field study in 1967 to compare: (a) in-
secticidal drift when applied simultaneously by ground rig and by "stan-
dard" aircraft sprayer; and (b) to determine the drift from morning versus
late afternoon applications.
Ground applications were made by a high clearance ground sprayer
(High Boy, Model 300 FSP, Hahn, Inc.) driven at 3 to 4 mph with 40-psi
boom pressure. Methoxychlor emulsion was applied in the evening test at
a rate of 70 gal. spray per 10 acres (1.5 Ib active ingredient per acre)
and in the morning test at a rate of 80 gal. spray per 10 acres (1.8 Ib
active ingredient per acre).
Aerial applications were made using a Stearman biplane flown at 80
mph (flight height not available) with a 42-ft swath, and 36 No. 8 nozzles
at 30 psi. Methoxychlor was applied at the rate of 70 gal. spray per 10
acres (2.0 Ib active ingredient per acre) in both the morning and evening
tests.
Meteorological conditions during the field tests were as follows:
(a) evening—wind from the northwest, 1 mph; temperature inversion of 3
degrees ranging from 83°F at 8 ft to 86°F at 32 ft; relative humidity not
recorded; and (b) morning—wind from the southeast, 1 to 2 mph; temperature
160
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lag of 0 to 2°F within 80 to 85°F; relative humidity varying from 72% at
7:00 a.m. to 55% at 9:00.
Relative drift during applications was determined by three Anderson
Air Samplers, four Casella® cascade impactors and one air scrubber (morn-
ing and evening tests) in addition to two M-S-A Monitaire® samplers at-
tached to the shirt pocket of the airplane flagman and Hi-Boy operator
(evening tests only). Naturally impinging drift was measured by glass
plates placed at ground level and 24 in. above ground in the target area
and at 82, 165, 330, 660, 1,320, 1,990, and 2,640 ft downwind for the
evening tests and in target area and at 82, 165, 330, and 660 ft downwind
for the morning tests. All analyses were by gas chromatography.
Conclusions drawn from this field test were as follows:
1. At all distances, drift from aerial application was greater than
from ground application (e.g., aerial application drift at 1,320 ft was
five times greater than ground application drift for the evening test;
aerial application drift at 660 ft was 4.2 times greater than from ground
application in the morning test application).
2. Impinging drift at ground level was the same quantity as that
at 24 in. In addition, drift deposits at these two levels were similar
for morning and evening aerial applications. However, deposit at 660 ft
for ground application in the morning was 2.6 times greater than deposit
for the evening application.
3. The M-S-A Monitaire® samplers determined methoxychlor exposure
was at a rate of 0.035 p,g/ft^ for the airplane flagman and 0.016 ^g/ft^
for the Hi-Boy operator; however, the ground equipment operator received
a greater pesticide exposure due to a greater exposure time (58 min ver-
sus 19 min).
4. Finally, it was determined that, at 165 ft downwind, more small
droplets were airborne during aerial application than during ground ap-
plication.
GROUND APPLICATION - EFFECTS OF AN ADDITIVE, NOZZLE PRESSURE, AND EVAPORA-
TION ON DRIFT
Paired field studies were performed by Goering and Butler (1973)—'
to evaluate ground rig sprayers. To assure application under identical
conditions, a dual sprayer, equipped with No. 8802 flat fan nozzles spaced
20 in. apart was mounted on the tractor to produce a swath width of 160
in. The tests were conducted using a dual application. Each mix tank con-
tained a different fluorescent dye tracer. Downwind drift was monitored
161
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by clear mylar collection sheets. Nozzles were calibrated with water
prior to drift experiments; measured flow rates were within 4% of the
expected rate.
The following effects were evaluated: (a) the effect of a spray
thickener additive on drift; (b) effect of nozzle pressure on drift; and
(c) effect of 2,4-D amine on evaporation and drift.
The tests consisted of conducting paired studies: (a) with and with-
out a spray additive (E-102) (Tests I, II, III, IV, and IX); (b) with and
without 2,4-D amine (Test V); and (c) with different nozzle pressures
(Tests VI, VII, and VIII). All test applications except one (V) contained
1.0% 2,4-D amine; V-a contained 0.0% 2,4-D amine. Results are shown in
Table A-8.
Spray recovery was 70% or more of the total applied in all experi-
ments except one. Conclusions from these studies were:
1. "The E-102 spray thickener reduced both the amount of drift de-
posits and the amount of spray loss by increasing deposits within the
swath."
2. "Lowering the nozzle height decreased the drift deposits."
3. "Lowering the nozzle pressure decreased the spray loss."
4. "Low temperatures and high relative humidity were associated
with decreased drift and decreased spray loss."
5. "Increased air turbulence produced greater spray loss, but less
downwind drift deposits."
6. "Increased horizontal wind speed produced greater spray loss,
but produced either greater or smaller drift deposits, depending upon
other meteorological factors."
GROUND APPLICATION - SPRAY DRIFT IN TREATING ORCHARDS
Pesticide spray treatment of orchards is normally done by sprayers
mounted on ground equipment. Thus, a considerable amount of the spray
must be directed upwards and as such, is subject to drift out of the or-
chard. Consequently, to avoid drastically harming nearby crops or wildlife
the fruit grower chooses relatively "safe" pesticides from which drift
hazard is minimal. Byass and Charlton (1964)ii/ conducted a study to mea-
sure the percentage of the applied pesticide impacting on the downwind
trees.
162
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Table A-8. SUMMARY OF RESULTS FROM PAIRED FIELD STUDIES OF DRIFT
Test
No.
I
II
III
IV
V
VI
VII
VIII
IX
a Control
b E-102
a Control
b E-102
a Control
b E-102
a Control
b E-102
a Control
b 2,4-D amine
a 40 psi
b 25 psi
a 40 psi
b 25 psi
a 40 psi
b 25 psi
a Control
b E-102
Temp
(°C)
14.6
11.9
17.9
14.7
13.9
22.3
27.8
30.1
31.7
Relative
humidity
(°/}
\'o)
51.0
50.0
23.0
48.0
47.0
29.0
38.0
38.0
42.0
E-102
("/}
\'°)
0.0
0.125
0.0
0.1
0.0
0.0625
0.0
0.0625
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
Cumulative
recovery
CL&
96.9
104.9
83.8
100.0
101.4
113.8
70.9
90.0
72.0
90.0
52.2
72.4
78.5
82.0
91.9
82.1
108.2
130.1
£/ Cumulative recovery includes deposits in the target area and
to 1,024 ft downwind. These figures may exceed actual re-
covery due to overcorrection for dye degradation and cor-
rection to zero wind direction; uncorrected figures ranged
from 48.8% to 100.3%.
163
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Narrow, folded celluloid slides with a high collection efficiency
(approximately 80% for 50 u. droplets at 10 ft/sec) and a size comparable
to twigs were used to estimate the amount of pesticide settling on twigs.
In addition, spray deposits on apple leaves were measured by dye colori-
metry. All dye applications were made in plain water solutions. Pertinent
meteorological data were recorded for all applications. Data from nine
application tests measuring percentage of deposit on the trees attribu-
table to drifting spray are shown in Table A-9.
It was concluded that in moderate winds: (a) "up to 40% of the final
deposit in an orchard sprayed at high volume by air-carried spray may be
due to spray settling beyond the sprayed row;" (b) "settling spray will be
at a level of about 10% of the dose applied to the sprayed tree at about
100 ft downwind;" if winds are light, settling amount is unpredictable;
and if winds are strong, 10% may settle 200 ft downwind.
164
-------
Ln
Table A~9. SPRAYING CONDITIONS AND PROPORTION OF TOTAL LEAF DEPOSIT
FROM DIRECT APPLICATION AND DRIFT
Machine
setting
(gal/acre)
8-1/3
8-1/3
10
50
50
125
200
200
250
Machine
speed
(ft/sec)
4.8
5.9
6.0
10.3
6.7
7.5
8.9
7.6
8.5
Temperature
(°F)
53
66
56
55
67
57
55
69
58
Relative
humidity
(%)
55
60
50
50
60
50
50
60
45
% Deposit
Target
rows
89
75
83
75
68
95
62
63
77
Downwind
1st
7
13
13
18
20
T
19
19
10
2nd
T*
7
3
4
7
T
9
9
6
rows
3rd
T
T
T
T
T
T
5
T
5
Beyond
3rd row
4
5
1
3
5
-
5
9
2
* Trace amount.
-------
REFERENCES TO APPENDIX A
1, Akesson, N. B., W. E. Yates, and P. Christensen, "Aerial Dispersion
of Pesticide Chemicals of Known Emissions, Particle Size, and
Weather Conditions," Paper furnished by authors.
2. Akesson, N. B., and W. E. Yates, "Physical Parameters Relating to
Pesticide Application," Personal Communication.
3. Ware, G. W., W. P. Cahill, P. D. Gerhardt, and K. R. Frost, "Pesti-
cide Drift IV: On-Target Deposits from Aerial Application of In-
secticides," £i_Jc^n._Entomoli, 6.3(4): 1982-1985 (1970).
4. Ware, G. W., B. J. Estesen, W. P. Cahill, and K. R. Frost, "Pesti-
cide Drift VI: Target and Drift Deposits vs. Time of Applica-
tions," £1_E£on._Entomol.r, 65(4):1170-1172, August 1972.
5. Brazzel, J. R., W. W. Watson, J. S. Hursh, and M. H. Adair, "The
Relative Efficiency of Aerial Application of Ultra-Low-Volume and
Emulsifiable Concentrate Formulations of Insecticides," J. Econ.
Entomol., 61(2):408-413 (1968).
6. Adair, H. M., F. A. Harris, M. V. Kennedy, M. L. Laster, and E. D.
Threadgill, "Drift of Methyl Parathion Aerially Applied Low Volume
and Ultra Low Volume," J. Econ. Entomol., 64(3):718-721 (1971).
7. Argauer, R. J., H. C. Mason, C. Corley, A. H. Higgins, J. N. Sauls,
and L. A. Liljedahl, "Drift of Water-Diluted and Undiluted Formula-
tions of Malathion and Azinphosmethyl Applied by Airplane," J. Econ.
Entomol., 6(14);1015-1020 (1968).
8. Ware, G. W., E. J. Apple, W. P. Cahill, P. D. Gerhardt, and K. R.
Frost, "Pesticide Drift II: Mist-Blower vs. Aerial Application
of Sprays," J. Econ. Entomol., 6£(4):844-846 (1969).
9. Ware, G. W., B. J. Estesen, W. P. Cahill, P. D. Gerhardt, and K. R.
Frost, "Pesticide Drift I: High Clearance vs. Aerial Application
of Sprays," J. Econ. Entomol., 62^(4) :840-843 (1969).
10. Goering, C. E., and B. J. Butler, "Paired Field Studies of Herbicide
Drift," fqr presentation at the 1973 Winter Meeting, ASAE, 11-14
December 1973, ASAE Paper No. 73-1575.
11. Byass, J. B., and G. K. Charlton, "Spray Drift in Apple Orchards,"
J. Agr. Eng. Res., 9(l):48-59 (1964).
166
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APPENDIX B
FIELD STUDIES ON PESTICIDE RUNOFF AFTER APPLICATION
167
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As a result of the review of the literature, a number of field
studies on the concentrations of pesticides in runoff water from crop-
lands and on the percentages of pesticides lost in runoff and soil ero-
sion were obtained. A brief discussion and the important findings of
each study are given below in the two separate categories given above.
The references used to obtain these studies appear at the conclusion of
this appendix.
CONCENTRATIONS OF PESTICIDES IN RUNOFF
For the data obtained in this section, we used nine field studies
conducted to determine the concentration (ppm) of pesticides in the
runoff water from field crops and watersheds. Each of these studies is
briefly described below and then the results of all the studies are sum-
marized.
1. Willisi' studied the concentration of endrin in surface runoff
from a sugarcane field on Mhoon clay loam soil in Baton Rouge, Louisiana.
The concentrations found were 1.06 and 0.46 ppb when rain followed the
application within 24 and 72 hr, respectively.
2. Kearney—' studied the concentration of 2,4-D, picloram, 2,4,5-T,
and dicamba in watershed runoff in North Carolina. The results of the
3-year study were: (a) no dicamba or picloram was detected, and the high-
est concentration of 2,4-D was 28 ppb, in 1967; (b) in 1968 the concentra-
tions measured were 1,224, 583, and 229 ppb for 2,4-D, 2,4,5-T and picloram,
respectively; and (c) the first storm gave the highest concentrations de-
tected in runoff for 2,4-D, 2,4,5-T, and picloram, and those concentrations
were 1,882, 681, and 4,187 ppb, respectively.
3. Axe et al.Z/ studied the concentrations of atrazine, propazine,
and trifluralin in runoff water from Pullman silty clay loam soil in West,
Texas. They found the highest concentrations to be 40, 50 and 40 ppb for
trifluralin, propazine, and atrazine, respectively.
4. Sheets et al»—' studied the concentration of picloram, 2,4-D,
and 2,4,5-T in runoff water from mixed grass sward-covered fields of loam
(sandy to clay) soil in Waynesville, North Carolina. During the 4-year
study, they found that the concentrations of 2,4-D in surface runoff from
the first rain after application were 1,200, 1,900 and 2,500 ppb, during
1968, 1969, and 1970, respectively. The concentrations for the other two
chemicals were less than those of 2,4-D. (They were not given.)
168
-------
5. Caro et al.—' studied the concentration of carbofuran in runoff
from silt loam soil planted in maize in Coshocton, Ohio. The results of
that study showed that concentrations in runoff were greatest within the
first month after application. For a broadcast application of carbofuran,
the runoff concentrations ranged from 1,394 ppb, 25 days after applica-
tion, to 5 ppb, 239 days after application. For a band application of
carbofuran, runoff concentrations ranged from 13,674 ppb, 28 days after
application, to 3 ppb, 119 days after application. In both cases, the
highest concentration was 677 ppb after 1 month from the time of appli-
cation.
6. Caro et al.— studied the concentration of dieldrin in runoff
water from a Muskingham silt loam soil watershed in Coshocton, Ohio. The
highest dieldrin concentration in the water was 20 ppb soon after appli-
cation, and did not exceed 4 ppb in two of the 3 years in which the study
was conducted.
7. Ritter et al.—' studied the concentrations of atrazine, propa-
chlor, and diazinon in runoff from four watersheds of silt loam soil in
Castana, Iowa. Atrazine ranged from 4,910 to 1,170 ppb in the 3-year
study. Propachlor was undetected in two of the 3 years, and ranged from
780 to 200 ppb in the other year. Diazinon was undetected in all but one
water sample, whose concentration was not given.
8. Hall et al.—' studied atrazine concentrations in runoff water
from 14 plots of Hagerstown silty clay loam soil planted in corn during
1967 and 1968. Amounts of atrazine applied at the recommended rate (2 lb/
acre) gave a concentration of 1,390 ppb in 1967 in the first storm. Each
successive runoff showed lesser concentrations, all below 200 ppb 1 month
after application, or later.
9. White et al.—' studied atrazine concentrations in runoff from
watersheds of Cecil sandy loam soil at Watkinsville, Georgia, in 1965. At-
razine applied 1 hr before a simulated rainstorm gave concentrations of
1,670 to 1,100 ppb in runoff, while application 96 hr before the storm
gave concentrations of 700 to 540 ppb in the runoff. Different intensity
storms showed that the average concentrations of atrazine in water for
runoff values of 0.07, 0.61, and 1.54 in. were 7,940, 2,540 and 1,390 ppb,
respectively, when applied 1 hr before the rain; and 3,660, 1,130, and
620 ppb, respectively, when applied 96 hr before the rain.
,169
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PERCENTAGES OF PESTICIDES LOST IN RUNOFF AND EROSION
Studies have been conducted on carbofuran, dieldrin, picloram, di-
azinon, propachlor, atrazine, and 2,4-D, to determine the amount of pes-
ticide lost in both the runoff and sediment as a percentage of the amount
applied. These studies are given below by pesticide, and the results of
these studies are subsequently discussed.
Carbofuran
In a study conducted by Caro et al. (1973)—' two watersheds planted
with maize were treated with carbofuran in 1971 and 1972 to determine the
runoff losses of the pesticide. Watershed No. 113 was silt loam soil with
an average slope of 9.67o. In 1971, No. 113 received a broadcast applica-
tion (disked into a 3 in. depth) of 4.83 Ib/acre active ingredient, and
No. 118 received an in-furrow treatment (band application) of 3.71 lb/
acre active ingredient. In 1972, No. 113 received an in-furrow applica-
tion of 2.77 Ib/acre active ingredient while No. 118 was not treated.
The important results of this study showed that:
1. The losses of carbofuran in runoff water in 1971 occurred almost
entirely within the first 2 days after application due to two heavy rains
in that period. These rains caused over 95% of the year's total losses
in both plots. The second rain produced higher concentrations than the
first from both plots, indicating the applied granules had dissolved by
the second day.
2. Losses due to runoff were less in the band application than in
the broadcast application for a given volume of runoff.
3. The total annual runoff losses of carbofuran, both in water and
soil, were less than 27o of that applied, as shown below:
Watershed Kilo liters Amount applied Type Carbofuran
No. Year of runoff (Ib/acre) application lost (%)
113 1971 44.7 4.83 Broadcast 0.9
118 1971 53.3 3.71 Band 0.5
113 1972 242.7 2.77 Band 1.9
170
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Dieldrin
A study was conducted in Coshocton, Ohio, from 1966 to 1969 by Caro
et al. (1971)V to determine the amount of dieldrin lost due to runoff
and erosion. Two watersheds of Muskingum silt loam were disked, ferti-
lized, and plowed 1 month before dieldrin was applied, and the applica-
tion was made immediately before maize was planted. In 1966, dieldrin was
applied to one plot as a uniform spray of aqueous solution from a 20 ft
truck boom at a rate of 5 lb/acre, and was immediately disked into the
soil to a depth of 3 in. In 1968, the other plot was treated the same
way, except that the soil was cultipacked deliberately to increase the
likelihood of runoff.
The 1966 plot had only two small runoff events in 1966 so no data
were obtained on runoff soon after application. The 1968 plot received
a rain 13 days after application, and half of the total loss of dieldrin
from this plot occurred at this time. The total loss of dieldrin due to
runoff and erosion was measured for 26 months on the 1966 plot, and for
8 months on the 1968 plots.
The results of this study were:
1. Dieldrin was lost from the soil mainly through volatilization
and soil erosion.
2. No measurable soil erosion occurred in the 1966 plot. In con-
trast, six of the 14 runoff events in 1968 resulted in soil erosion from
the plot. Dieldrin concentrations in the soil lost were about three orders
of magnitude higher than in the associated runoff water, and 2.2% of the
dieldrin applied to the 1968 plot was lost due to soil erosion.
3. Dieldrin losses in the runoff water were 0.0077o of the amount
applied in the 1966 plot, measured over a 26-month period, and 0.07% in
the 1968 plot, measured over an 8-month period.
4. Losses of the pesticide due to soil erosion were about 30 times
greater than losses due to the associated water runoff.
5. The largest losses occurred within 2 months of application.
6. No relationships were found between concentrations of dieldrin
lost and volume of runoff water, maximum flow rate, or duration of run-
off. No continuous decrease of concentration occurred with time.
171
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Picloram
Picloram was applied to 96 separate experimental plots in a study
conducted by Baur et al. (1972)!/ in Carlos, Texas, in 1969 and 1970 to
determine the concentrations of the pesticide in runoff water. Treatments
consisted of 1.12 kg/ha of picloram sprayed at the rate of 93.5 liters/ha
with a tractor-mounted sprayer. The runoff water was sampled over a 2-year
period, and the plots were sprayed each year at various intervals (each
plot received only one spray treatment annually).
The results of this study showed that samples of runoff water taken
adjacent to the plots had a high value of 89.7 ppb (parts per billion)
picloram 2 days after application and declined to less than 10 ppb by
10 to 12 weeks after application. Water sampled 1.2 km from the plots
contained less than 1 ppb of picloram, 8 days after application. Eight
months after treatment, occasional levels of less than 1 ppb were de-
tected 1.6 km from the plots. In addition, most of the picloram was re-
moved by runoff within the first 16 weeks of application, and about 50%
of the total pesticide loss occurred within the first 4 weeks.
Other studies were summarized in this article and are given belows
1. Scifres et al. applied picloram to soil at the rate of 0.28 kg/
ha. They detected 17 ppb in runoff water the first few days after appli-
cation. Less than 1 ppb level of picloram in runoff water was detected
when sprinkler irrigation was conducted 20 to 30 days later.
2. Davis et al. applied picloram at the rate of 1.04 kg/ha to soil
in Arizona. Seven days after the application, high levels of 370 ppb were
detected in runoff water following a 6.43-cm rain. The picloram was found
in trace amounts 3 months after treatment and was undetectable after 12
months.
3. Johnsen and Warskow applied picloram to Arizona soil at the rate
of 1.9 kg/ha. Runoff water from the watershed over an 18-month period
showed that only 0.0570 of the picloram was lost due to runoff waters.
These studies show that "the concentration of picloram in runoff
water is related to the rate applied, time between application and first
rainfall, amount and intensity of rainfall, and size of watershed as it
influences dilution."
Diazinon
A study was conducted by Ritter et al. (1974)—' in Castana, Iowa,
for 4 years, 1967 to 1970, to determine the loss of diazinon, propachlor,
172
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and atrazine due to runoff and erosion. Four watersheds were used that
consisted of silt loam soil and had slopes of 10 to 15%. In 1967, the
plots were planted to surface-contour corn and two of them were ridged
at the first cultivation. From 1968 to 1970 two of the plots were planted
to surface-contour corn, and two were planted to ridged corn.
Diazinon was applied to the four plots at the first cultivation each
year in a band application 1 to 2 in. deep at a rate of 1 Ib/acre. (Atra-
zine and propachlor were also used in the study and are considered in the
following sections.) The results obtained for diazinon in this study were:
1. No significant amounts of diazinon were found in the surface
runoff and sediment when applied at recommended rates and incorporated
into the soil.
2. Highest concentration if diazinon was found in runoff and sedi-
ment samples collected 4 to 10 days after application, with a maximum of
0.17o of the total pesticide applied to the watershed in the runoff and
sediment from one of the surface-contoured plots due to a storm occurring
4 days after application.
3. No severe storms occurred in the 2-year study period and the
reason the losses of diazinon were low was that it was incorporated into
the soil and degraded rapidly.
Propachlor
Ritter et al. (1974).6-/ studied propachlor also. In 1967 and 1968,
propachlor was applied to both a contoured plot and ridged plot at the
rate of 4 Ib/acre by spraying a wettable powder formulation. In 1969 and
1970, the same procedure was followed except that the rate of application
was increased to 6 Ib/acre. The runoff and sediment were then examined
for propachlor.
Results of the study on propachlor were:
1. No runoff occurred in 1968 and 1969 before the propachlor had
degraded.
2. In 1967 no detectable amounts of propachlor were found in water
or sediment runoff from samples collected 14 and 25 days after applica-
tion.
173
-------
3. In 1970 a storm occurred 7 days after application and 2.6% of
the propachlor was lost in the runoff from the surface-contoured plot:
2.0% in the water and 0.670 in the sediment. Runoff measurements 25 and
37 days after the application showed no propachlor loss in the sediment,
and .a total loss of 0.5% in the runoff water during that period. (All per-
centages are percent of total propachlor applied.) The total propachlor
lost in the first 37 days then, was 3.1% of the total applied.
No loss occurred in the ridged plot in 1970 since the pesticide de-
graded prior to runoff occurrence.
Atrazine
Again using the same study in Castana, Iowa, atrazine was studied
in addition to propachlor and diazinon. In 1967 and 1968, atrazine was
applied to both a contour-surface plot and a ridged plot at the rate of
2 Ib/acre by spraying a wettable powder formulation. In 1969 and 1970,
the same procedure was used except that the rate was increased to 3 lb/
acre. The runoff and sediment were then examined for atrazine loss during
1969 and 1970.
The results of this study were:
1. The amount of atrazine lost in the sediment and water runoff de-
creased with time after application. Two months after application, the
runoff from storms contained insignificant amounts of atrazine.
2. Total losses of atrazine in the runoff for 1969 and 1970 are sum-
marized below. The percentages given are atrazine losses as a percent of
the total amount applied.
Atrazine in water
Surface-
Year Ridged contoured
1969 . 3.8% 6.3%
.1970 2.5% 12.3%
Atrazine in sediment Atrazine loss, total
Surface- Surface-
Ridged contoured Ridged contoured
0.1%
0.2%
1.9%
3.7%
3.9%
2.7%
8.2%
16.0%
3. The storm that occurred 7 days after application in 1970 re-
moved 15% of the total atrazine applied to the surface-contoured plot.
The ridged plot suffered a 2.2% loss during the same storm.
174
-------
Another study was conducted by Hall et ali (1972)2/ on atrazine
losses in runoff water and soil sediment in 1967 and 1968. The atrazine
was applied preemergent to corn on 14 plots of Hagerstown silty clay
loam soil (14% slope). Seven different rates of application were used,
each applied to two separate plots; they were: 0, 0.6, 1.1, 2.2, 4.5,
6.7, and 9.0 kg/ha. The plots were treated only once, on 19 May 1967.
Runoff and soil erosion was then sampled for atrazine losses from the
plots over the next 2 years.
The results of this study were:
1. The total amounts and the percentage of atrazine lost in runoff
water and soil sediment in 1967 were:
Rates applied Amounts (g/ha) Percent
Water Soil Water and soil
1.7 0.03 1.73
3.6 0.07 3.67
2.3 0.20 2.50
2.0 0.17 2.17
2.1 0.22 2.32
2.7 0.28 2.98
2.4 0.16 2.56
Note: The recommended rate of application was 2.2 kg/ha in 1967
2. In 1968, 1 year after atrazine application, the average loss for
all rates was 0.01%.
A third study was performed by White et al. (1967)—' at Watkinsville,
Georgia, in 1965, on a Cecil sandy loam soil of 6.5% slope. Atrazine was
applied to the soil surface at the rate of 3 Ib/acre, and simulated rain-
fall was used to produce runoff and erosion. Three storm sizes were pro-
duced to represent different storms occurring in the area. Storm sizes of
0.5, 1.25, and 2.50 in. of water were used, and represent a relatively
common storm; a 1-year frequency storm; and a 10-year frequency storm, re-
spectively. Losses were determined for atrazine due to storms occurring
1 hr after application and 96 hr after application.
Results of the study showed that:
1. Atrazine applied to the surface of a dry soil is lost mainly by
photodecomposit ion and volatilization. In a laboratory study by Kearney
et al. (1964) it was found that when atrazine was applied to several soils
at 95°F, up to 40% was lost by the above process in a 72-hr period.
175
(kg/ha)
0.6
1.1
2.2
4.5
6.7
9.0
Means
Water
10.0
40.0
50.0
90.0
140.0
240.0
95.0
Soil
0.2
0.8
4.3
7.5
14.9
24.9
8.8
Water and soil
10.2
40.8
54.3
97.5
154.9
264.9
103.8
-------
2. The effects of storm size on atrazine losses in the runoff water
and soil sediment were:
Atrazine in washoff
Storm
size
(in.)
0.5
1.25
2.50
Rainfall Applied 1 hr before rain Applied 96 hr before rain
duration Total loss Total loss
(min) (Ib/acre) % Lost (Ib/acre) % Lost
12
30
60
0.13
0.36
0.50
4.3
12.0
17.0
0.06
0.16
0.22
2.0
5.3
7.3
3. The losses shown for the 0.5-in. storm and 96-hr treatment are
the most representative of field conditions. This condition gives a loss
of 2.0% of atrazine in the washoff.
4. The greatest losses occurred when the rain occurred immediately
(1 hr) after the application.
5. Losses of 0.1 Ib/acre or less would be most frequently encoun-
tered under actual field conditions.
2.4-D
Barnett et al. (1967)12/ conducted a study of 2,4-D using Cecil soil
(5% slope), and showed that losses in washoff were 137o for the butylether
ester and 4% for the amine salt forms of 2,4-D. The application rate was
2.2 Ib/acre, and measurements were taken following a 30-min rain of 1.25
in. This suggests that atrazine and 2,4-D are similar in their suscepti-
bility to loss by washoff from agricultural land. (Atrazine showed a 1270
loss from the same rain, 1 hr after treatment.)
176
-------
REFERENCES TO APPENDIX B
1. U.S. Environmental Protection Agency, "A Catalog of Research in
Aquatic Pest Control and Pesticide Residues in Aquatic Environ-
ments," May 1972.
2. Axe, J. A., A. C. Mathers, and A. F. Wiese, "Disappearance of Atra-
zine, Propazine, and Trifluralin from Soil and Water," 22nd Annual
Meeting of the Southern Weed Science Society, Proceedings, 21-23
January 1969.
3. Sheets, T. J., W. L. Rieck, and J. F. Lutz, "Movement of 2,4-D,
2,4,5-T, and Picloram in Surface Water," Southern Weed Science
Society, Proceedings (1972).
4. Caro, J. H., H. P. Freeman, D. E. Glotfelty, B. C. Turner, and
W. M. Edwards, "Dissipation of Soil-Incorporated Carbofuran in
the Field," J. Agr. Food Chem., 2^(6):1010-1015 (1973).
5. Caro, J. H., and A. W. Taylor, "Pathways of Loss of Dieldrin from
Soils Under Field Conditions," J. Agr. Food Chem., 19(2);379-384
(1971).
6. Ritter, W. F., H. P. Johnson, W. G. Lovely, and M. Molnau, "Atra-
zine, Propachlor, and Diazinon Residues on Small Agricultural
Watersheds. Runoff Losses, Persistence, and Movement," Environ.
Sci. Techno1., 8(l):38-42 (1974).
7. Hall, J. K., M. Pawless, and E. R. Higgins, "Losses of Atrazine in
Runoff Water and Soil Sediment," J. Environ. Quality, 1X2): 172-
176, April/June 1972. ~
8. White, A. W., A. B. Barnett, B. G. Wright, and J. H. Holladay,
"Atrazine Losses from Fallow Land Caused by Runoff and Erosion,"
Environ. Sci. Technol., 1X9);740-744 (1967).
9. Baur, J. R., R. W. Bovey, and M. G. Merkle, "Concentration of Pi-
cloram in Runoff Water." Weed Sci., 20(4) :309-313, July 1972.
10. Barnett, A. P., E. W. Hauser, A. W. White, and J. H. Holladay, "Loss
of 2,4-D. Wash-Off from Cultivated Fallow Land," Weeds, 1.5:133-
137 (1967).
177
-------
APPENDIX C
PESTICIDE USAGE ON THE U.S. CORN, SORGHUM. AND
APPLE CROPS (1971)
178
-------
The information in this appendix was obtained from: (1) "Farmers'
Use of Pesticides in 1971--Quantities," Agricultural Economic Report No.
252, Economic Research Service, U.S. Department of Agriculture (1974b);
(2) MRI estimates of individual pesticide usage by region; and (3) U.S.
Department of Agriculture, "Agricultural Statistics, 1973," U.S. Govern-
ment Printing Office, Washington, D.C. (1973).
Figure C-l shows the USDA farm production regions (10) that are re-
ferred to throughout the appendix. Figures C-2 and C-3 show the U.S. corn
and sorghum acreage planted in 1971 (by state), respectively. Figure C-4
shows the U.S. commercial apple production (in millions of pounds) by
state in 1971. Statistics for Figures C-2 through C-4 were obtained from
reference (3) above.
Tables C-l through C-ll give the pesticide usage on the three crops
in 1971. tables C-l, C-5, and C-7 were obtained from references (1) above.
The remainder of the tables were all developed by MRI based upon the in-
formation given in reference (1) above. These tables show the estimated
usage of the individual major pesticides on each crop—corn, sorghum and
apples—by region.
179
-------
U.I. DEPARTMENT OF AGRICULTURE
NEC. ERS IJWA-4J (I) ECONOMIC RESEARCH URVICE
Figure C-l. Farm production regions,
180
-------
Corn Acreage Planted for All
Purposes in Thousands of Acres
Total Acreage = 74,055,000
Figure C-2. U.S. corn acreage (1971), by state.
-------
Table C-l. PESTICIDE USAGE ON U.S. CORN CROP IN 1971 BY REGION
00
to
Herbicides
Region
Northeast
Lake States
Corn Belt
Northern Plains
Appalachian
Southeast
Delta States
Southern Plains
Mountain
Pacific
Total
1,000 Ib
5,250
21,358
54,069
10,700
6,166
2,105
474
127
566
245
101,060
7.
5.2
21.1
53.5
10.6
6.1
2.1
0.5
0.1
0.6
0.2
100.0
Insecticides
1,000 Ib
155
2,749
15,314
5,852
375
42
37
54
928
25
25,531
7.
0.6
10.8
60.0
22.9
1.5
0.2
0.1
0.2
3.6
0.1
100.0
Miscellaneous
pesticides
1,000 Ib 7.
1 0.2
-
-
386 87.1
•
-
-
>
-
56 12.7
443 100.0
Total pesticides^/
1,000 Ib
5,406
24,107
69,383
16,938
6,541
2,147
511
181
1,494
326
127,034
7.
4.3
19.0
54.6
13.3
5.1
1.7
0.4
0.1
1.2
0.3
100.0
aj Fungicides used on corn are not listed separately in the USDA report. Fungicides are not included in the
pesticide total in this table.
Source: "Farmers' Use of Pesticides in 1971 - Quantities," Agricultural Economic Report No. 252, Economic
Research Service, U.S. Department of Agriculture (1974b).
-------
Table C-2. HERBICIDES USED ON CORN, BY REGION, 1971~
(1,000 Ib)
oo
10
Herbicide
Atrazlne
Propachlor
2,4-D
Alachlor
Butylate
Slmazlne
Llnuron
Propazine
EPTC
Dicamba
MCPA
Others
Total
North-
east
3,600
85
350
850
120
110
10
-
10
3
2
110
5,250
Lake
States
13,000
5,250
1,250
1,000
160
120
30
100
50
75
323
21,358
Corn
Belt
23,600
13,900
4,800
5,900
3,800
500
600
190
50
150
4
575
54,069
-
Northern
Plains
6,300
2,000
1,500
100
150
-
100
170
100
60
75
145
10,700
Appalachian
4,500
5
750
400
195
120
10
21
•
-
-
165
6,166
Regions
South-
east
350
-
200
50
1,250
50
5
185
10
-
-
5
2,105
Delta
States
300
40
60
20
-
-
20
2
-
-
-
32
474
Southern
Plains
50
10
9
20
-
-
5
13
2
1
-
17
127
Mountain
250
-
200
20
43
-
20
-
10
10
-
13
566
Pacific
50
10
25
-
100
20
4
2
10
10
3
11
245
Total
52,000
21,300
9,144
8,360
5,818
920
804
583
292
284
159
1.396
101,060
Source: "Farmers' Use of Pesticides in 1971 - Quantities," Agricultural Economic Report No. 252, Economic
Research Service, U.S. Department of Agriculture (1974b).
£/ Use of each individual insecticide, by region, is an MRI estimate.
-------
Table C-3. INSECTICIDES USED ON CORN, BY REGION, 1971
(1,000 Ib)
Insecticide
Aldrin
Bux
Carbofuran
Phorate
Diazinon
Carbaryl
Parathion
Heptachlor
Chlordane
Disulfoton
Others
Total
North-
east
—
5
50
2
5
20
5
4
35
8
21
155
Lake
States
90
810
790
200
300
100.
50
10
200
30
169
2,749
Corn
Belt
7,350
1,370
1,140
1,700
800
400
40
1,090
560
20
844
15,314
Northern
Plains
235
1,360
630
400
780
1,000
900
-
•
120
427
5,852
Appalachian
40
.
20
50
20
100
25
-
30
30
60
375
Regions
South-
east
20
-
4
1
1
2
2
-
4
-
_8
42
Delta
States
10
-
12
1
-
1
-
-
-
-
11
37
Southern
Plains
1
30
-
5
-
5
5
-
3
2
_3
54
Mountain
10
-
30
300
80
20
300
-
8
100
80
928
Pacific
3
-
5
2
5
1
2
.
2
2
_3
25
Total
7,759
3,575
2,681
2,661
1,991
1,649
1,329
1,104
842
312
1.628
25,531
£/ Figures for total use of each insecticide and regional totals were obtained from "Farmers' Use of
Pesticides in 1971 - Quantities," Agricultural Economic Report No. 252, Economic Research Service,
U.S. Department of Agriculture (1974b).
b_/ Use of each individual insecticide, by region, is an MR! estimate.
-------
Table C-4. MISCELLANEOUS PESTICIDES USED ON CORN, BY REGION, 1971-
(1,000 Ib)
a.b/
Pesticide
Dicofol
Regions
North- Lake Corn Northern Appalachian South- Delta Southern
east States Belt Plains east States Plains Mountain Pacific Total
- - . . . . . 56 56
co
Other
Miticldes
Miscellaneous
Fumlganta
Total
336
386
386
443
a/ Figures for total use of each pesticide and regional totals were obtained from "Farmers' Use of
Pesticides in 1971 - Quantities," Agricultural Economic Report No. 252, Economic Research Service,
U.S. Department of Agriculture (1974b).
b/ Use of each individual pesticide, by region, is an MRI estimate.
-------
oo
Sorghum Acreage Planted for All
Purposes in Thousands of Acres
Total Acreage = 20,756,000
Figure C-3. U.S. sorghum acreage (1971), by state.
-------
Table C-5. PESTICIDE USAGE ON U.S. SORGHUM CROP IN 1971
oo
By Region^/
Herbicides
Region
Northeast
Lake States
Corn Belt
Northern Plains
Appalachian
Southeast
Delta States
Southern Plains
Mountain
Pacific
1,000 Ib
14
--
1,176
5,834
310
125
287
3,486
251
55
7.
0.1
0.0
10.2
50.6
2.7
1.1
2.5
30.2
2.1
0.5
Insecticides
1.000 Ib
..
—
94
1,301
28
406
339
2,927
398
236
%
0.0
0.0
1.6
22.7
0.5
7.1
5.9
.51.1
7.0
4.1
Total Pesticides-/
1,000 Ib
14
--
1,270
7,135
338
531
626
6,413
649
291
%
0.1
0.0
7.4
41.3
2.0
3.1
3.6
37.1
3.7
1.7
Totals 11,538 100.0 5,729 100.0 17,267 100.0
a/ Source: "Farmers Use of Pesticides in 1971--Quantities," Agricultural Economic Report
No. 252, Economic Research Service, U.S. Department of Agriculture (1974b) .
b_/ Fungicides and miscellaneous pesticides are not listed separately in the above report,
and are not included in this table.
-------
Table C-6. HERBICIDES USED ON SORGHUM, BY REGION,
(1,000 Ib)
oo
. oo
Region
Herbicide
Atrazine
Propazine
2,4-D
Propachlor
Norea
Arsenicals
MCPA
Others
Total
North-
east
5
-
4
3
-
-
-
_2
14
Lake Corn
States Belt
400
350
200
100
50
10
10
- 56
0 1,176
Northern Appa-
Plains
2,600
500
1,000
1,250
200
-
70
214
5,834
lachian
160
20
60
.
50
10
-
10
310
South-
east
75
5
20
'
5
10
-
10
125
Delta
States
115
30
45
50
10
20
- '
17
287
Southern
Plains
700
1,680
600
20
100
100
20
266
3,486
Moun-
tains
110
-
100
-
-
20
14
7
251
Pacific
10
-
10
10
3
15
5
_2
55
Total
4,175
2,585
2,039
1,433
418
185
119
584
11,538
a/ Figures for total use of each herbicide and regional totals were obtained from "Farmers' Use of Pesticides
in 1971—Quantities," Agricultural Economic Report No. 252, Economic Research Service, U.S. Department
of Agriculture (1974b).
b_/ Use of each individual herbicide, by region, is an MRI estimate.
-------
Commercial Apple Production in
Millions of Pounds
Total Production
Total Not Utilized ( )
Total Production for
Use or Sale
6,371.1
290.5
= 6,080.6 million
pounds
Figure C-4. U.S. commercial apple production (1971), by state.
-------
Table C-7. PESTICIDE USAGE ON U.S. APPLE CROP IN 1971 BY REGION
Fungicides
Region
Northeast
Lake States
Corn Belt
Northern Plains
Appalachian
Southeast
Delta States
Southern Plains
Mountain
Pacific
1,000 Ib
2,943
1,026
853
12
1,353
67
-
-
16
937
I
40.8
14.3
11.8
0.2
18.8
0.9
-
-
0.2
13.0
Herbicides Insecticides Misc. Pesticides
1.000 Ib % 1.000 Ib
128 65.0 2,403
349
11 5.6 831
5
1 0.5 359
6 3.0 32
.
.
44
51 25.9 808
% 1.000 Ib %
49.8 116 21.1
7.2 29 5.3
17.2 36 6.6
0.1
7.4 27 4.9
0.7 7 1.3
.
0.9 23 4.2
16.7 310 56.6
Total Pesticides
1.000 Ib
5,590
1,404
1,731
17
1,740
112
-
-
83
2,106
%
43.7
11.0
13.5
0.1
13.6
0.9
0
0
0.7
16.5
Totals 7,207 100.0 197 100.0 4,831 100.0 548 100.0 12,783 100.0
Source: "Farmers' Use of Pesticides in 1971 Quantities," Agricultural Economic Report No. 252, Economic Research
Service, U.S. Department of Agriculture (1974b).
-------
Table C-8. FUNGICIDES USED ON APPLES BY REGION,
(1,000 Ib)
Fungicide
Cap tan
Other dithio-
carbamates
Dinocap, dodine,
quinones
Other inorganics
Zineb
Other organic s
Maneb
Ferbam
Other copper
compounds
Copper sulfate
Total
North- Lake
east States
1,250 800
800 20
600 160
65
50 1
80 30
25
70 15
1
2
2,943 1,026
Corn
Belt
400
200
50
1
100
5
50
-
45
_2
853
Regions
Northern Appa- South-
Plains lachian east
900
10 200
1 3 10
15
180 5
1 9 10
40
20 5
15
1 7
12 1,353 67
Delta Southern Moun-
States Plains tain Pacific
2 40
- - 2 65
2 95
460
4 170
1 40
5 5
8
50
4
0 0 16 937
Total
3,392
1,297
921
541
510
176
125
118
111
16
7,207
a/ Figures for total use of each fungicide and regional totals were obtained from "Farmers' Use of Pesticides in 1971--
Quantities," Agricultural Economic Report No. 252, Economic Report No. 252, Economic Research Service, U.S.
Department of Agriculture (1974).
b/ Use of each individual fungicide, by region, is an MRI estimate.
-------
Table C-9. INSECTICIDES USED ON APPLES BY REGION, 197l£* (1,000 Ib)
Insecticide
Inorganics
Aziophosmethyl
Other
Organophosphorus
Carbaryl
Chlordane
Parathion
Endosulfan
Ethion
Malathion
VO
N5 Diazinon
Bidrin
Methoxychlor
Dieldrin
Other
Organochlorine
Endrin
TDE (ODD)
Heptachlor
Total
North- Lake
east States
900 10
500 100
300 80
300 100
200 50
60 5
100 2
35
-
6 2
-
1
1
-
-
-
2,403 349
Corn
Belt
500
60
35
100
100
10
10
-
5
4
4
2
-
-
-
831
Northern Appa-
Plains lachian
140
100
1 40
30
10
3 15
10
1
10
1
2
1
-
-
' -
-
5 359
South- Delta Southern Moun-
east States Plains tain
3 - -
7 - - 2
2 - - 3
1 - - 2
2 - - 4
5 - - 15
2 - - 10
5 - - 3
2
.
3
1
1
.
2 - - -
1 - - -
32 0 0 44
Pacific
300
200
160
180
50
7
25
2
25
4
5
3
2
3
2
-
-
808
Total
1,853
969
641
583
373
138
136
69
21
18
12
7
.5
2
2
1
1
4,831
a/ Figures for total use of each insecticide and regional totals were obtained from "Farmers' Use of Pesticides in 1971--
Quantities," Agricultural Economic Report No. 252, Economic Research Service, U.S. Department of Agriculture (1974b).
b/ Use of each individual insecticide, by region, is an MRI estimate.
-------
Table C-10. HERBICIDES USED ON APPLES BY REGION, 1971-
(1,000 Ib)
«LJ>/
Herbicide
Other Organic
Slmazlne
to Dalapoo
u>
2,4-D
Dlaltro Group
Dluroa
Trlfluralln
Total
North- Lake Cora Northern
east States Belt Plains
65 - 1
20 - 5
25 - 1
15 3
2 ...
1
1
128 0 11 0
Regions
Appa- South- Delta Southern Moun-
lachian east States Plains tain Pacific
1 - 28
1 10
3 5
I 4
1 ... 3
... 1
_=_ _s_ _r_ _^ _i_ -JL_
1 60 0 0 51
Total
95
36
34
23
6
2
1
197
a/ Figures for total use of each herbicide and regional total were obtained from "Farmers' Use of Pesticides in 1971-
Quantities," Agricultural Economic Report No. 252, Economic Research Service, U.S. Department of Agriculture (1974b).
b_/ Use of each Individual herbicide, by region, is an MR I estimate.
-------
Table C-ll. MISCELLANEOUS PESTICIDES USED ON APPLES BY REGION,
(1,000 Ib)
North- Lake Corn Northern Appa- South- Delta Southern Moun-
Pesticlde east States Belt Plains lachlan east States Plains tain
Mltlcldes
Dlcofol 1 -- - ~ ' '"' 2
Omlte 69 10 28 - 9 - - - 2
Others 32 - - - ' 10 2 - - 9
Fumigants - ... - -- - -
Defoliants and
Deslccants - ... - -- - -
Rodentlcldes 5 ... - -- - -
Plant Growth
Regulators 9 19 8 - 85 - -10
Repellents i - _ji " _Z _1_ _Z_ _I_ _1
Total 116 29 36 0 27 70 0 23
Pacific Total
3 6
160 278
30 83
0
0
2 7
115 174
_- 0
310 548
a/ Figures for total use of each pesticide and regional totals were obtained from "Farmers' Use of Pesticides In 1971-
Quantities," Agricultural Economic Report No. 252, Economic Research Service, U.S. Department of Agriculture (1974b),
b/ Use of each individual insecticide, by region, is an MRI estimate.
-------
APPENDIX D
PESTICIDE APPLICATION RATES RECOMMENDED BY THE
USDA AND MANUFACTURERS' PRODUCT LABELS
195
-------
Table D-l. USDA RECOMMENDED PESTICIDE APPLICATION RATES
Apples
VO
HERBICIDES
Alachlor
Atrazine
Butylate
Da lap on
2,4-D
Norea
Propachlor
Propazlne
Ib
3.7 when trees are less
than 4 years old
7.4 when trees are 4
years or older
2.0 do not allow spray
to contact leaves,
fruit or stem of
tree
Corn
Ib AI/acre&/
3.5 preplant
4.0 preemergence
4.0 preplant, preemergence
and postemergence
4.0 preplant
11.1 preplant fall
6.0 preplant spring
0.3 early postemergence
1.5 postemergence
2.0 p reeme rge nc e
1.5 postemergence
1.3 after early dough
stage
6.0 preemergence
Sorghum
Ib
4.0 preplant, preemergence
and postemergence
6.0 preplant
2.0 preemergence
1.0 postemrgence
0.75 postemergence
(as lithium salt)
2.4 preemergence
5.25 preemergence
3.2 preemergence
-------
Table D-l. (Continued)
Apples
Ib AI/acre-'
Corn
Ib
Sorghum
Ib AI/acre-
INSECTICIDES
Aldrin
Azinphosmethyl
Bux
6.0 (7 days)-''
vo
2.0 broadcast application
1.0 preplant
0.25 (as dry bait formulation)
around base of plant
(30 days)b-/
1.0 (as granular formulation)/
13,080 ft of row or
0.4 oz/325 ft of row at plant-
ing
4.0 broadcast
2.0 oz/bushel-seed treatment
Carbaryl
Carbofuran
Chlordane
Diazinon®
12.0 (1 day)i
b/
8.0 (30 days)~
10.0 (as soil prepara-
tion when no fruit
is present)
6.0 (14 days)^
2.0 (forage)
3.0 (at time of plant)
1.0
3.0 (granular formulation)
2.0
2.0 oz/bushel-seed treatment)
1.25 (spray)
1.6 (dust)
1.0 (as a spray at the base
of plants at planting time)
2.0 (soil application to
furrow)
5.2 (granular; at time of
planting)
5.5 (spray)
10.0 preplant
2.0 oz (bushel-seed treatment)
2.0 (21 days for grain; no
limit for forage)-/
2.0 oz/bushel-seed treatment
0.5 (7
4.0 preplant
2.0 (granular)
2.0 oz/bushel-seed treatment
-------
Table D-l. (Continued)
vo
oo
Apples
lb AI/acre-'
INSECTICIDES (Continued)
Disulfoton
Endosulfan
Heptachlor
Malathion
2,5 (not after hull
split)
9.0 (not after petal
fall)
4.0 (30 days)Ji/
2.5 (30 days or 21
days)6-/
Methyl Bromide
Methyl Parathlon 6.0 (14 days)-
Corn
lb Al/acreS/
1.2 oz/1,000 ft of row
1.0 (40 in. row spacing)
3.0 (soil only)
5.0 (soil only; peat and
muck soils only)
1.6 (dust) (5 days)-'
b/
b/
1.25 (spray) (5 days)-'
2.0/1,000 ft3-fumigation
b/
Sorghum
lb AI/acre-/
0.5 (spray; 40 in. row spacing)
1.2 oz/1,000 ft of row
0.25 (12 days)-'
2.0 oz/bushel-seed treatment
10.0 oz/1,000 bu; mixed with
grain; postharvest storage
treatment only
5.0 oz/1,000 ft grain surface;
postharvest storage only, i.e.,
0.9 (spray) (7 days)^
4.0/1,000 ft -fumigation
1.0 (21
-------
Table D-l. (Concluded)
VO
INSECTICIDES (Concluded)
Parathion
Phorate
Toxaphene
Captan
Dinocap®
Dodine
Sulfur
Zineb
Apples
Ib Al/acre-
6.0 (14 days)-/
b/
16.0 (40 days)-
10.0
0.127. solution
(postharvest)
3.0 (21 days)-7
4.0 (7 days)-''
1.6 (5 days)-/
3.75 (7
170.0
12.0
Corn
Ib AI/acre-'
1.0 (12 days)-''
1.0 (granular; 40 in. row
spacing)
(30 days)^/
2.0 oz/1,000 ft row
2.0 (granular)
6.0
3.2 oz/1,000 Ib seed
Sorghum
Ib AI/acre-
1.0 (12 days)6-''
1.0 (granular)
1.2 oz/1,000 ft row
2.0 (28
3.0 (40 days)6-/
2 oz/bushel-seed treatment
3.0 oz/100 Ib seed dry mixture
2.3 oz/100 Ib seed (slurry
mixture)
3.0
a/ Rates are expressed terms of pounds active ingredient applied per acre or in terms of ounces
active ingredient.
b_/ Designates number of days required between last application and harvest.
Source: USDA Summary of Registered Agricultural Pesticide Chemical Uses, Vol, I, II, and III. Pesticides
Regulation Division, Agricultural Research Service, United States Department of Agriculture.
-------
Table D-2. PESTICIDES MOST COMMONLY USED ON APPLES; APPLICATION RATES
RECOMMENDED ON PRODUCT LABELS
Manufacturer
Trade Name
Target Pest(s)
Recommended Application
O
O
Fungicides
Copper Compounds
Dinocap
Dithlocarbamates
Coordination produce of
zinc and maneb
Zineb
Corporation
Rohm and Haas
Company
Rohm and Haas
Company
Rohm and Haas
Company
FMC Corporation
Rohm and Haas
Company
Rohm and Haas
Company
0-0-0-53
507. copper expressed
as metallics
KarathaneB
4 Ib Al/gal
Kflrathane®
207. Al/lb
Dikar®
72% Al/lb
Dithane® M-45
80S Al/lb
Zlneb UP
75% Al/lb
Dithane® Z-78
757. Al/lb
Dithane® Z-78
75% Al/lb
Fire blight
Powdery mildew
Apple scab, powdery mildew,
black rot, bitter rot,
brown rot, Cedar apple
rust, fly speck, sooty
blotch, European red
mite, Schoene mite, two-
spotted mite, clover mite
.Bitter rot, black rot,
brown rot, Cedar apple
rust, fly speck, scab,
sooty blotch
Scab, sooty blotch, fly
speck. Brooks spot,
black rot
Apple blotch, bitter rot,
black rot, Botryasphaeria
fruit rot, Brooks spot,
Cedar rust, fly speck,
frogeye, scab, sooty
blotch, quince rust
Fire blight
1/4 lb/100 gal. water; first appli-
cation when 20% of the blossoms
are open, repeat when 75% are
open
4 to 6 oz/100 gal. water
(500 to 800 gal. spray/acre)
Spray program should be planned
through Extension Service
On a spray schedule: 1-1/2 to
2 lb/100 gal. water
Concentrate spray: 8 to 10 Ib/acre
for mature trees
1 to 2 lb/100 gal. water
(10 Ib/acre)
1 to 1-1/2 lb/100 gal. water
1 to 2 lb/100 gal. water, maximum
of 10 Ib/acre or 1/2 to 1 Ib
when used with captan or glyodin
2 lb/100 gal. water (10 Ib/acre)
-------
Table D-2. (Continued)
Fungicides
Dodlne
Sulfur
N>
O
Herbicides
Dalapon
Si.mazi.ne
Nitralln
(California only)
Manufacturer
American Cyanamid
Company
Trade Name
Target Pest(s)
FMC Corporation
FMC Corporation
FMC Corporation
FMC Corporation
Stauffer
Chemical Company
Dow Chemical
Company
Clba-Geigy
Shell Chemical
Company
Cyprex- wp
657. Al/lb
Kolospray^
81% Al/lb
Kolo^- 100
757. Al/lb
Kolodusc-'
Xtra Dust or Spray
537. Al/lb
Kolodust^
847. Al/lb
Magnetic® "95"
957. Al/lb
Dowpon-1
74% Al/lb
Prlncep2 SOW
Planaviri® 75WP
75% Al/lb
PlanavlriE 4
4 Ib Al/gal
Scab
Scab, powdery mildew
Scab
Scab
Scab, powdery mildew
Scab, powdery mildew
Johnsongrass
control In orchards
Controls many annual weeds
Control of broadleaf weeds
and grasses
Control of broadleaf weeds
and grasses
Recommended
Application Rate
Protection schedule: 1/4 to 1/2
lb/100 gal. water
After Infection: 3/4 lb/100 gal.
water
Air application: 1-1/2 Ib/acre In
5 to 7 gal. water
(allow 28 days before harvest)
6 to 8 lb/100 gal. water or 4 to 6
plus 2 to 3 Ib Polysulflde Com-
pound/100 gal. water
3-1/2 lb/100 gal. water
5 to 8 lb/100 gal. water; after scab
is under control, 2 to 4 lb/100
gal water
40 to 50 Ib/acre
6 to 8 lb/100 gal. water in prebloom,
bloom, and petal fall sprays;
4 to 6 lb/100 gal. water la cover
sprays
5 to 10 Ib/acre under trees
2-1/2 to 5 Ib/acre under trees (do
not apply to sandy soil)
2-2/3 to 5-1/3 Ib/acre after harvest
and before June 1 of the next year
4 to 8 qt/acre after harvest and
before June 1 of Che next year
Insecticides
Azlnphosmethyl
Chemagro
Guthlort1 WP
50% Al/lb
Aphlds, apple maggot, codling
moth, European apple sawfly,
eye-spotted bud moth, Forbes
scale, fruit tree leaf rol-
ler, green frultworm, leaf-
hoppers, mealybug, mites,
orange tortrlx, pear psylla,
plum curculio, Putnam scale,
red-banded leaf roller,
San Jose scale, stink bug,
1/2 to 5/8 lb/100 gal. water
(maximum of 1,000 gal. spray/acre)
-------
Table D-2. (Continued)
Manufacturer
Trade Name
Target Pests(s)
Recomnended
App I teat ton Rate
Insecticides (Continued)
Carbaryl
O
NJ
Dlmethoate
Endosulfan
Methyl Parathion
Union Carbide
Corporation
American Cyanamld
Company
FMC Corporation
Monsanto
Sevirti
807. Al/lb
Sevin® SOW
50% Al/lb
25WP
25% Al/lb
CygonS 267
2.67 Ib Al/gal
ThiodanS 3 Dust
37. Al/lb
Thiodan=> 50WP
50% Al/lb
4 Ib Al/gal
Apple sucker, green apple
aphid, woolly apple aphid,
apple aphid, bagworm,
codling moth, apple rust
mite, eye-spotted bud moth,
green frultwonn, Lygus bugs,
orange tortrix, scales,
mealybug
Apple sucker, aphids, mites,
codling moth, scales,
Lygus bugs, orange tortrix
Mealybug, green apple, aphid,
codling moth, white apple
leafhopper
Apple maggot, bagworm, other
aphids, mites, scales
Aphids, leafhoppers, mites,
(except rust mites)
Aphids, leafhoppers, mites
(except rust mites)
Apple aphid
Apple aphid, rosy apple
aphid
Apple rust mite, woolly
apple aphid
Aphids, codling moth, plum
curcullo, scales, red-
banded leaf roller
West of the Rocky Mountains:
1 to 1-1/4 lb/100 gal. spray;
East of the Rocky Mountains:
2/3 lb/100 gal. spray
(allow 1 day before harvest)
West of the Rocky Mountains :
1-1/2 to 2 lb/100 gal. spray
East of the Rocky Mountains:
1 lb/100 gal. spray
2 lb/100 gal. water
(allow 1 day before harvest)
1 to 2 lb/100 gal. water
3/4 to 1-1/2 pt/100 gal. water
(allow 28 days before harvest)
50 Ib/acre
I lb/100 gal. water
(maximum of 4 to 5 Ib/acre)
1 lb/100 gal water
(maximum of 8 Ib/acre)
1/2 to 1 pt/100 gal. water
(maximum of 6 qt/acre)
-------
Table D-2. (Concluded)
Manufacturer
Trade Name
Target Pests(s)
Recommended
Application Rate
Insecticides (Concluded)
Para th ton
Monsanto
Niran® E-4
4 Ib Al/gal
European sawfly, scales, mealy- 1/2 pt/100 gal. water
bugs, mites, bagworms, codling
moths, leaf rollers, plum
curculio
Grasshoppers
Bud moth, mites, aphids, leaf-
hoppers, leaf miners, red bug
3/4 pt/100 gal. water
3/8 pt/100 gal. water
(maximum of 1-1/2 gal/acre)
O
to
Miticides
Propargite
Vended 50
Uni.royal Chemical
Shell Chemical
Company
Omlte® 30W
307. Al/lb
Vended 50
507. Al/lb
European red mite, two-spotted
mite, Pacific spider mite,
McDaniel mite
European red mite. MeDaniel
Spider mite, two-spotted
mite, apple rust mite
5 to 12 Ib/acre
East of Rocky Mountains:
1-1/4 to 1-1/2 lb/100 gal. water
(allow 7 days before harvest)
4 to 8 oz/100 gal. water
(maximum of 800 gal. spray/acre)
-------
Table D-3. PESTICIDES MOST COMMONLY USED ON CORN; APPLICATION RECOMMENDED ON PRODUCT LABELS
Manufacturer
Trade Name
Target Pest(s)
Recommended
Application Rate
Fungicides
Dithlocarbamates
Coordination Product
of Zinc and Maneb
Rohm and Haas Company Dithane^ M-45
80% Al/lb
Helmlnthosporian
leaf blight
1-1/2 Ib/acre; minimum of 25 gal.
water/acre
Zineb
FMC Corporation
Zineb WP
75% Al/lb
Helminthosporian
leaf blight
1-1/2 to 2 lb/100 gal. water
Herbicides
Alachlor
to
Monsanto
Atrazine
Butylate
2,4-D
Ciba-Geigy
Stauffer Chemical
Company
Dow Chemical Company
15% Al/lb
Lasso& 10G
107. Al/lb
Lasso® EC
4 Ib Al/gal
AAtrex® SOW
80% Al/lb
AAtrex^' 4L
4 Ib Al/gal
Sutan- +
6.7 Ib Al/gal
2,4-D (LV)
4 Ib Al/gal
2,4-D
(alkanol amine salt)
4 Ib Al/gal
Annual grasses, sedges,
annaul broadleaves
Grass and weed control
Grass and weed control
Broadleaf weed and grass
control
Broadleaf weed and grass
control
Annual and perennial grasses,
broadleaf weeds
Weed control
Weed control
Broadcast: 16 Ib/acre
Band: (40 in. row spacing)
2.8 to 4.0 Ib/acre
Broadcast: 20 to 40 Ib/acre
Band (40 in. row spacing):
7.0 to 12.2 Ib/acre (rate
depending on soil type)
Preplant: 2.5 to 3.5 qt/acre
Broadcast: 2.5 to 3.5 qt/acre
(rate depending on soil type)
Broadcast; preplant, preemergence
Postemergence: 2.5 to 3.75 Ib/acre
(rate depending on soil type)
Broadcast; preplant, preemergence
Postemergence: 4 to 6 pt/acre
(rate depending on soil type)
Broadcast: (sandy soil)
3-3/4 pt/acre
Preemergence: I to 2 qt/acre
Emergence: 1 pt/acre
Postemergence: 1/2 pt/acre
Preemergence: 2 to 4 pt/acre
Emergence: I pt/acre
Postemergence to 8 in: 1/2 to I pt/acre
8 in. to tasseling: 1 pt/acre
-------
Table D-3. (Continued)
Herbicides (continued)
2,4-D (continued)
Manufacturer
Rhodia, Chipman
Division
Transvaal, Inc.
to
O
Ui
Propachlor
Monsanto
Trade Name
2,4-D L.V.
ester
4 Ib Al/gal
Target Pest(s)
2,4-D amlne
No. 4
4 Ib Al/gal
Weed-Rhapc
A-4D
2,4-D amine
4 Ib Al/gal
Weed-Rhap®
B-6D
6 Ib Al/gal
butyl ester of
2,4-D
Weed-Rhap~
LV-6D
6 Ib AI/2,4-D/gal
Ranirod- 65
65% Al/lb
Ramrod"5- 20G
20% Al/lb
Rararocf^/atrazine
69''; Al/lb
Weed control
Weed control
Weed control
Weed control
Weed control
Selective preemergence
weed control
Selective preemergence
weed control
Selective preemergence
weed control
Recommended
Application Rate
Preemergence: 1 to 2 qt in
10 to 20 gal. water/acre; on
muck and clay soil, 1/2 to 1
gal/acre
Postemergence: 1/2 to 3/4 pt/acre
With Nitrogen: 2/3 to 1 pt/acre with
80 to 120 Ib nitrogen
1/2 to 1 pt/acre
1 pt in 5 to 10 gal. water/acre
1/3 pt in 5 to 10 gal. water/acre
Preemergence: 1.3 to 2.6 pt in
5 to 10 gal. water/acre
1/3 pt in 5 to 10 gal. water/acre
Broadcast: 6 to 9 Ib in 20 gal.
water/acre (rate depending on
soil type)
Preemergence: 6 to 9 Ib in 8 gal.
water/acre
Broadcast: 20 to 30 Ib/acre
Band (40 in. row spacing'):
7.0 to 10.5 Ib/acre
Broadcast: 5 to 8 Ib in 20 gal.
water (rainimura)/acre
Band: 5 to 8 Ib in 8 gal. water
(minimum)/acre
-------
Table D-3. (Continued)
Insecticides
A Idrin
Manufacturer
Shell Chemical Company
N>
O
Bux
Carbaryl
Chevron, OrCho Division
Union Carbide
Trade Name
Aldrin
4 Ib Al/gal
Aldrin 20G
207. Al/lb
BUX- Ten 10G
107. Al/lb
Sevln® SOW
507. Al/lb
Sevin5' sprayable
807. Al/lb
Sevimol^ 4
4 Ib Al/gal
Carbofuran
FMC Corporation
Furadan- 4 flowable
4 Ib Al/gas
Target Pest(s)
Rootwonn, dlabrotica larvae
Annual grubs, ants,
cutworms, false wtreworms,
fleabeetle larvae, Japanese
beetle grub, seed-corn
beetle and maggot, wireworms,
European chafer grub, grape
colaspis, white grubs
Rootworm, diabrotica larvae
Annual grubs, ants, cut-
worms, false wireworms,
fleabeetle larvae, Japanese
beetle grub, seed-corn
beetle and maggot, wireworms,
European chafer grub, grape
colaspis, white grubs
Corn Rootworm
Corn, earworm, corn root worm
adults, European corn borer,
fall armyworm, flea beetle,
Japanese beetle, sap beetle,
leafhoppers
Cutworm
Corn earworm, corn rootworm
adults, European corn
borer, fall armyworm, flea
beetle, Japanese beetle,
leafhoppers
Cutworm
Corn earworm, corn rootworm
adults, grasshoppers,
European corn borer,
Southwestern corn borer,
fall armyworm, flea
beetles, Japanese beetle,
sap beetle
Western bean cutworm
Corn rootworm
Recommended
Application Rate
Broadcast: 1 qt/acre
Broadcast: 1-1/2 to 2 qt/acre
Band: 1 qt/acre
Broadcast: 3 qt/acre
Band: 1 qt/acre
Band: 5 Ib/acre
Broadcast: 7-1/2 to 10 Ib/acre
Band: 5 Ib/acre
Broadcast: 15 Ib/acre
7.5 to 10 Ib/acre (40 in. row
spacing)
2 to 4 Ib/acre
4 Ib in 50 gal. water (minimum)/acre
1-1/4 to 2-1/2 Ib/acre
2-1/2 Ib in 15 gal. water (minimum)/acre
1-1/2 qt/acre
2 qt/acre
1-1/2 to 2 pt/acre at plant (40 in.
-------
Table D-3. (Continued)
Manufacturer
Trade Name
Target Pest(s)
Recommended
Application Rate
Insecticides (continued)
Carbofuran (continued)
Furadan0 10 Granules
107. Al/lb
Diazinon-
N>
O
Ciba-Geigy
Diazinon^ AG500
4 Ib Al/gal
Diazinon® SOW
507, Al/lb
Corn rootworm, flea beetles,
European corn borer, stalk
rot (decrease insect wounds),
armyworm, fall armyworm,
Northern, Western, and
European corn rootworras
Southwestern corn borer
(2nd and 3rd generation)
European corn borer (1st
generation), wireworms
NemaCodes
Corn rootworm adults
Corn leaf aphids
Mites, flea beetles,
grasshoppers
Sap beetles
Corn rootworm
larvae
Seed corn maggot,
cutworms
Wireworms
Corn leaf aphid
Grasshoppers
Sap beetle
Plant, post plant, and foliar:
7-1/2 to 10 Ib/acre (40 in.
row spacing)
15 to 30 Ib/acre at plant
20 to 30 Ib/acre at plant
(40 in. row spacing)
15 to 20 Ib/acre at plant
(40 in. row spacing)
1/2 to 1 pt/acre
1 to 2 pt/acre
1 pt/acre
2 to 2-1/2 pt/acre
(aerial: minimum of 1 gal.
water/acre)
(ground: minimum of 5 gal.
water/acre)
Postemergence basal treatment:
1 to 2 Ib/acre (40 in. row spacing)
Broadcast: 4 to 8 Ib/acre prior
to plant
6 to 8 Ib/acre
1 to 2 Ib/acre
1 Ib/acre
2 to 2-1/2 Ib/acre plus 1 to 2 gal.
soluble mineral oil/acre
Diazinon'1' 14G
147. Al/lb
Corn rootworm larvae,
lesser cornstalk borers
European corn borers,
fall arm/worms, South-
western corn borers
Cutworms, seed corn maggots
Garden symphylans
(centipedes)
Wireworms
Postemergence basal treatment:
3-1/2 to 7 Ib/acre (40 in. row
spacing)
7 to 14 Ib/acre
Broadcast:
Broadcast:
14 to 23 Ib/acra
70 Ib/acre
Broadcast: 21 to 28 lb/acrs
-------
Table D-3. (Concluded)
Insecticides (continued)
Parathion
Manufacture r
Monsanto
Kerr-McGee Chemical
Corporation
Trade Name
Niran® E-4
4 Ib Al/gal
Parathion
Granular-4
4% Al/lb
Target Pest(s)
European corn borer
Corn leaf aphids
Fall armyworms, corn
earworms, corn rootworm
adults, armyworms to
third instar, climbing
cutworms, grasshoppers,
Japanese beetles
Stink bugs, spider mites
Chinch bugs
Wireworms
Recommended
Application Rate
1 pt/acre
1/2 pt/acre
3/4 pt/acre
1 pt/acre
1-1/2 pt/acre
25 Ib/acre in furrow at plant
Phorate
N>
O
00
American Cyanamid
Company
Thtmet31 10G
10% Al/lb
Thimet® 15G
15% Al/lb
Corn rootworms,
European corn borer
(1st generation)
Corn rootworms,
European corn borer
(1st generation)
10 Ib/acre (40 in. row spacing)
10 Ib/acre (40 in. row spacing)
(allow 30 days before harvest)
6.5 Ib/acre (40 in. row spacing)
6.5 Ib/acre (40 in. row spacing)
(allow 30 days before harvest)
-------
Table D-4. PESTICIDES MOST COMMONLY USED ON SORGHUM; APPLICATION RECOMMENDED ON PRODUCT LABELS
Herbicides
Atrazine
Manufacturer
Ciba-Geigy
o
VO
2,4-D
Dow Chem. Co.
2,4-D
Rhodia Chipman Div.
Transvaal, Inc.
Trade Name
AAtrex 80W
807. Al/lb
AAtrea© 4L
4 Ib Al/gal
2,4-D (LV)
4 Ib Al/gal
2,4-D (al-
kanol amine
salt) 4 Ib
Al/gal
2,4-D Amine
No. 4
4 Ib Al/gal
Weed-Rhap©
A-4D 4 Ib
AI 2,4-D
amine/gal
Weed-Rhap®
B-6D 6 Ib
AI butyl ester
of 2,4-D/gal
Target Pest(s)
Broadleaf weed and grass
control (medium and fine
textured soils only)
Broadleaf weed and grass
control (medium and fine
textured soils only)
Weed control
Weed control
Weed control
Weed control
Weed control
Recommended Application Rate
Broadcast preplant and preemergence:
2 to 3 Ib/acre (rate depending on
soil type) broadcast, postemergence:
2.5 to 3.75 Ib/acre (rate depending
on soil type)
Broadcast, preplant and preemergence:
3.2 to 4.75 pts/acre (rate depending
on soil type) broadcast, postemer-
gence: 4 to 6 pts/acre (rate de-
pending on soil type)
Postemergence: 1/2 pt/acre
Postemergence: 2/3 to 1 pt/dcre
Postemergence: 1 pt/acre
1 pt in 5 to 10 gaL water/acre
1/3 pt in 5 to 10 gal. water/acre
-------
Table D-4. (Continued)
Herbicides
Manufacturer
2,4-D continued Transvaal, Inc
Ni
t->
O
Propachlor
Propazine
Insecticides
Carbaryl
(old label)
Monsanto
Ciba-Geigy
Union Carbide
Corp.
Trade Name
Weed-Rhap©
LV-6D 6 Ib
Al/gal
Ramrod® 65 WP
65% Al/lb
Ramrod® 20 G
20% Al/lb
Ramrod®/
atrazine 69%
Al/lb
Milogard®
80 W 80%
Al/lb
Sevin®
Sprayable
80% Al/lb
Sevin®50-W
50% Al/lb
Target Pest(s)
Weed control
Selective preemer-
gence weed control
Selective preemer-
gence weed control
Selective preemer-
gence weed control
Broadleaf weed and grass
control (not for use on
sandy or loamy sand soils)
Annyworms, corn ear-
worm, stink bugs, webworms
sorghum midge
cutworm
Armyvorms, corn ear-
worm, stink bugs, webworms
sorghum midge
cutworm
Recommended Application Rate
1/3 pt in 5 to 10 gal. water/acre
Broadcast: 6 to 7.5 Ib in 20 gal.
water (minimum) per acre, band: 2
to 2.5 Ib in 8 gal. water (minimum)
per acre (40 in. row spacing)
Broadcast: 20 to 25 Ib/acre
band: 7.0 to 8.8 Ib/acre
(40 in. row spacing)
Broadcast: 5 to 8 Ib in 20 gal.
water (minimum) per acre
Preplant and preemergence: 1-1/2
to 4 Ib/acre (rate depending on
state and soil type)
1-1/4 to 2-1/2 Ib/acre
1-7/8 Ib/acre
2-1/2 Ib/acre
(allow 21 days before harvest)
2 to 4 Ib/acre
3 Ib/acre
4 Ib/acre
(allow 21 days before harvest)
-------
Table D-4. (Continued)
Insecticides
Carbaryl
continued
Manufacturer
Union Carbide
Corp.
Disulfoton
Chemagro
Methyl Parathion Monsanto
Parathion
Monsanto
Trade Name
Sevimol® 4
4 Ib Al/gal
Di-Syston®
15G 15%
Al/lb
Di-Syston©
6 Ib Al/gal
Di-Syston©
107. Al/lb
Niran®M-4
4 Ib Al/gal
Niran©E-4
4 Ib Al/gal
Phorate
American Cyanamid
Company
Thimet@600
6 Ib Al/gal
Target Pest(s)
Armyworms, corn ear-
worm, stink bugs, webworms
sorghum midge
Southwestern corn borer
cutworm
Aphids (greenbugs)
Aphids (greenbugs),
sorghum midge in some
states
Aphids (greenbugs)
Corn leaf aphids, mites
sorghum midge
Sorghum midge
cornleaf aphids, mites
sorghum webworm, fall
armywonns, annyworms to
third instar, corn ear-
worms
Aphids (greenbugs)
Recommended Application Rate
1 to 2 qt/acre
1-1/2 qt/acre
2 qt/acre
(allow 21 days before harvest)
5 to 6.7 Ib/acre (40 in. row spacing)
(allow 30 days before harvest)
1/3 to 2/3 pt/acre
(allow 30 days before harvest)
7-1/2 to 10 Ib/acre (40 in. row
spacing) (allow 30 days before
harvest)
1 pt/acre
1 pt to 1 qt/acre
(allow 21 days before harvest)
1 pt to 1 qt/acre
1/2 pt/acre
3/4 to 1 pt/acre
(allow 21 days before harvest)
2/3 to 1-1/3 pt/acre
(allow 28 days before harvest)
-------
Table D-4. (Concluded)
Insecticides
Toxaphene
Manufacturer
Hercules, Inc.
Trade Name
Target Pest(s)
Toxaphene dust Cutworm, corn earworm
20% Al/lb armyworms, grasshoppers
Toxaphene 60% Armyworms, cutworms
E.G. 6 Ib
Al/gal
Recommended Application Rate
7-1/2 to 15 Ib/acre
(allow 28 days before harvest)
1-1/2 to 2 qt/acre
(allow 40 days before harvest)
to
i-1
to
-------
APPENDIX E
EXTENSION SERVICE RECOMMENDED PESTICIDE APPLICATION RATES
FOR APPLES. CORN. AND SORGHUM IN SELECTED STATES
213
-------
PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop
Type of Pesticide: Insecticides
Year : 1974
State:
Pound Active Ingredient Per Acre
Recommended
to
£
i
Target
Pesticide3-/ Pest(s)V
D ( 5 Y 5 '^"V ' '
t
JDir* &1\h r\ T~SL H
By Extension
Service
0 • ** ^-ty
' - '/ s '
?/ ~\ 'id7'/vT cA7*
By Suppliers
0.5-
0.5
Generally
Used by
Growers
(?.^
o.$
Minimum
Effective
Rate
0,33
/I C""
(/ » ^
Total Acreage Versus Acreage
Treated with Insecticides/
ITimlili hli i in the State
Approximate number of acres
in your state (1974) -
?(,<>, d<>6
- Planted: ^ o
-f /4,
1.9
\ Lfr.
- Harvested for grain:
- Needing insecticide/
hefbieida treatment:
3?, 000
- Actually treated at least
once with any insecticide/
hcrbicidei *,_..,
_!/ Please list the insecticides/^Mchifefcdfee (four or five) most frequently used on o»**i/sorghum in your
state, in decreasing order of volume of use.
2J Please list the most important insects/ws^dc, in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
PESTICIDE APPLICATION DATA
N>
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
crop V >UcxW^.
J
Type of Pesticide:**
Year :
State:
HfiX^Lx'A.^
1974
Pound Active Ingredient Per Acre /
Target By
Pesticide!/ Pest(s)b_/
-l^XlA/vtM— ^ >4uH*^0Jt t/utdih*
* 11 l^^M_A £_-*"**-<—
\J U-0-I+ ,
Recommended
Extension
Service By Suppliers
f- ^ ^^
Generally Minimum^-
Used by Effective
Growers Rate
L^ ^
6JL**A,
.
7" h-^ -^•'*i- - - ' \ A
"f/j>» t v dU/-A. /.^y.Ql^bw-M_/^
^ n^ ivv-
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
in your state (1974) -
feA^^A^ L <.
' V
i, 4 -D
- Planted: M 80, 00 O
- Harvested for grain:
- Needing iiuiH.ii.idi>/
herbicide treatment
- Actually treated at least
once with any i«»*e»bM*d
herbicide:
»/sorghum in your
I/ Please list the rnflccbietde-s/herbicides (four or five) most frequently used on <
state, in decreasing order of volume of use.
2/ Please list the most important MtBECtc/weeds, in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop :
Type of Pesticide:
Year : 1974
State:
/'3--
to
Pound Active Ingredient Per Acre
Recommended
Target
Pesticide^/ Pest(s)b/
By Extension
Service
By Suppliers
Generally
Used by
Growers
Minimum
Effective
Rate
fj j J t~
-SuACLTtA***. btzrl^
/
f.C,
2..0
/*
/<£
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
in your state (1974) -
-Planted: 3L.j0OO.00G
- Harvested for grain: /j
- Needing insecticide/
jiopbieidc treatment: /
- Actually treated at least
once with any insecticide/
herbicide: g~c
\J Please list the insecticides/hmibi nidm (four or five) most frequently used on corn/.a*acgkwa in your
state, in decreasing order of volume of use.
7J Please list the most important insects/mmdiE., in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop WTTN^. :
Type of Pesticides
Year : 1974
Pound Active Ingredient Per Acre
State:
Recommended
Target
Pesticide^/ Pest(s)b/
By Extension
Service
By Suppliers
Generally
Used by
Growers
9-1*
1-3-
**
X.'Ltr
Minimum
Effective
Rate
*•
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
in your state (1974) -
- Planted:
- Harvested for grain: oj£*»
f(
+4t
- Needing inaceteieftdc/ ffrv ***&/Jfe-4^?
herbicide treatment: ^//y^ J&*. '
- Actually treated at least
once with any i^c^ofeicide/
herbicide:
\^l Please list the tnDrr-r-'r-f«ki'i/hrrh1"i'^f>T (four or five) most frequently used on corn/^s^gtwaia in your
state, in decreasing order of volume of use.
2/ Please list the most important i«e&»£s/weeds, in decreasing order of importance, against which the
listed pesticides are recommended, and used.
-------
PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop
Type of Pesticide:
Year : 1974
State
*'
oo
Pound Active Ingredient Per Acre -
| Target 2- By Extension
PesticideK/ Pest(s)JE/ Service
C u
J& -to /.
.75"-fc
/.£>
By Suppliers
l.fi -h L 5"
.75- -fa /^
Generally
Used by
Growers
Minimum
Effective
Rate
Total Acreage Versus Acreage
Treated with Insecticides/
N H^cb.lfH^F. in the State
/.£>-(*/£*
Approximate number of acres
in your state (1974) -
/.O
2..O
.15 •*> /.5"
A«
^t.O
.75T -te/.5"
2- •>*>
i *>
- Planted: /c
- Harvested for grain: ^3,^^506
- Needing insecticide/
horbieido treatment:
- Actually treated at least
once with any insecticide/
lit-iliirrrtg; (0 £57 cso
_!/ Please list the insecticides/bai>bwAdos (four or five) most frequently used on corn/aoirei'Wtt in your
state, in decreasing order of volume of use.
2/ Please list the most important insects/i»ead», in decreasing order of importance, against which the
listed pesticides are recommended and used.
/
-------
PESTICIDE APPLICATION DATA
VO
Return tog
Midwest Research Institute
425 Volker
Kansas City
Attng K. A
Boulevard
, Missouri 64110
o Lawrence
Crop
Type of
Year
0
Pesticides
*
a
Corn
Insecticide
1974
States
Indiana
Pound Active Ingredient Per Acre
Recommended
Pesticide!/
Aldrin
Chlordane
Furadan
Thimet w
Dyfonate
Target By
Pest(s)W
NCR
Cutworms v
Wireworms/
Extension
Service By
1
2
NCR Not Rec.
Cutworms
Wireworms
W & NCR
W & NCR
W & NCR
Wireworms
4
4
3/4
1
1
4
Suppliers
1/2-1*
1-2*
1-2*
2-4*
3/4-1
1
3/4-1
4
Generally
Used by
Growers **
1
1-2*
1-2*
4
4
1
1
1
4
Minimum
Effective
Rate**
1
1-2*
__
—
3/4
1
1
4
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
in your state (1974) -
- Planted; 5.6 million
- Harvested for grains 5.5 million
- Needing insecticide/
- Actually treated at least
once with any insecticide/
bapbJaAdag 2.6 million**
JL/ Please list the insecticides/begblcidsg (four or five) most frequently used on com/&®
-------
PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop :
Type of Pesticide:
Year : 1974
State
N>
O
Pound Active Ingredient Per Acre
Recommended
Target
Pesticide3-/ Pest(s)W
By Extension
Service
By Suppliers
Generally
Used by
Growers
3- -3
r
7*
0
Minimum
Effective
Rate
2 "
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
in your state (1974) -
- Planted: /3-.'?0^'
- Harvested for grain: //
/
- Needing M
herbicide treatment:
- Actually treated at least
once with any i«BBO>i8ida
herbicide:
_!/ Please list the JTtco"ti":l'1"T/h"rK'i""'''"'• (four or five) most frequently used on corn/DB»fthum in your
state, in decreasing order of volume of use.
2J Please list the most important Lnmmm^c/weeds, in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
PESTICIDE APPLICATION DATA
Return to:
Midvest Research Institute
•^25 Volker Boulevard
Kansas City, Missouri 64110
Atcn: K. A. Lawrence
Crop
Type of Pesticide:
Year : 1974
State:
Pound Active Ingredient Per Acre
NJ
Target
Pesticide^/ Pest(s)j>/
Recommended Generally
By Extension Used by
Service 87 Suppliers Growers
/ <+ -I i t y- /.••**-
1+** '*** A/*~
t fitl fit I
* ' 1 /
Minimum
Effective
Rate
/ V ">L
/**-
1
I
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
in your state (1974) - /^ fi^ C>tf^>
- Planted:
- Harvested for grain: //
- Needing insecticide/
-treatment:
- Actually treated at least
• once witn any insecticide/
^ ^-0 #
_!_/ Ploase list the insecticides/tiEi'baioiries (four or five) most frequently used on corn/
ctatc, in decreasing order of volume of use.
'ij Please list the ip.ost important insect s/w*&4s, in decreasing order of importance, against which the
listed pesticides arc recommended and used.
-------
PESTICIDE APPLICATION DATA
Return to:
Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop ' :
Type of Pesticide: /Jerk'' CJ
Year : 1974
State:
N>
ro
ro
Pound Active Ingredient Per Acre
Recommended
Target
Pesticide^/ Pest(s)V
By Extension
Service
By Suppliers
Generally
Used by
Growers
M in imum
Effective
Rate
ft*
r^t
G-r***y
/— 3
&>£-/
Sti-e.
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
in your state (1974)
- Planted:
- Harvested for grain:
. Needing
herbicide treatment:
- Actually treated at least
once with any
herbicide:
_!/ Please list the inaeafwf(tiffins/herbicides (four or five) most frequently used on corn/aogghum in your
state, in decreasing order of volume of use.
2J Please list the most important Anooates/weeds, in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
State:
Type of Pesticide:
Year /
N)
CO
Pound Active Ingredient Per Acre
Recommended
Pesticide!
a/
Target
P'est(s)j>/
By Extension
Service
By Suppliers
Generally
Used by
Growers
Minimum
Effective
Rate
-6' -3- a
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
in your state (1974) -
- Planted:
- Harvested for grain:
- Needing iiiaeetiaidc/
herbicide treatment:
- Actually treated at least
once with any ineoofciaidc/
herbicide:
\J
sorghum in your
Please list the »WB«**»4d*6/herbicides (four or five) most frequently used on
state, in decreasing order of volume of use.
2J Please list the most important iuaoetc/weeds, in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
PESTICIDE APPLICATION DATA
ro
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop
Type of Pesticide: /
Year / t) -?'f : 1974
State:
Pound Active Ingredient Per Acre
Recommended
Target
Pest(s)b/
By Extension
Service
By Suppliers
Generally
Used by
Growers
M in imum
Effective
Rate
&^JL-&*4
3#£
-eu sy*-*^'
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
in your state (1974) - ^ £>O tif r*r*>
in your
\J Please list the imsooO-teiides/herbicides (four or five) most frequently used on corn/!
state, in decreasing order of volume of use.
2/ Please list the most important icoootoc/weeds, in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop : corn
Type of Pesticide: Insecticides
Year : 1974
State: Missouri
Pound Active Ingredient Per Acre
Recommended
Pesticide3-
a/
Target
Pest(s)b/
By Extension
Service
to
to
Cn
aldrin
carbofuran
toxaphene
phorate
carbaryl
Cutworms anal/., c. o
wire worms *-?<" *
Rootworms
1.0
Complex of above 1.5G
ground feeders 1.5-3«OS
Rootworms
1.0
Complex of above 1.5 G
ground feeders 1.0-2.0 S
By Suppliers
unknown
Generally Minimum
Used by Effective
Growers Rate
unknown Ext. Ser,
Rec,
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
in your state (1974) -
Data not released yet
- Planted: by USDA-Statistical
Reporting Service
- Harvested for grain:
- Needing insecticide/
herbicide treatment:
- Actually treated at least
once with any insecticide/
iiii.biiidi; unknown
I/ Please list the insecticides/hogbiaiiimc (four or five) most frequently used on corn/
in your
state, in decreasing order of volume of use.
2/ Please list the most important insects/«*«iss in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop : Sorghum
Type of Pesticide: Insecticide
Year : 1974
State: Missouri
Pound Active Ingredient Per Acre
N>
to
Target By
Recommended
Extension
Pesticide^/ Pest(s)Ji/ Service By Suppliers
Toxaphene
parathion
diazinon
malathion
Corn earworm
Pall army worm
Greenbugs
Midge
Midge
Greenbugs
2 0
, * c ~ Unknown
1 • 5 (s
2.0 S
0.375
0.5
0.5 "
15 ozs. "
Generally
Used by
Growers
Unknown
seldom
used by
growers
n
it
Minimum
Effective
Rate
Ext. Ser
Rec.
n
n
n
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
in your state (1974) -
Data not released yet
- Planted:by USDA-Statistical
Reporting Service
- Harvested for grain:
- Needing insecticide/
treatment: unknown
- Actually treated at least
once with any insecticide/
lie.ibii«iJi: unknown
/sorghum in your
J7 Please list the insecticides/haaibAaidaa (four or five) most frequently used on
state, in decreasing order of volume of use.
2J Please list the most important insects/«****s, in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
PESTICIDE APPLICATION DATA
Crop Corn :
Type of Pesticide: Insecticides
Year : 1974
State: Nebraska
Pound Active Ingredient Per Acre
NJ
•vl
Recommended
Target By Extension
Pesticide!/ Pest(s)b./ Service By Suppliers
Carbofuran
Phorate
©
Dasanit
€>
Dyfonate
corn rootworms 1 Lb.
corn rootworms 1 Lb.
» « 1 Lb.
» « 1 Lb.
.75-1.0 Lbo
1 Lb.
1 Lb.
1 Lbo
Generally Minimum
Used by Effective
Growers Rate
0.8 - 1.0 Oo75
1 Lbo
1 Lbc
1 Lb.
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
in your state (1974) -
- Planted: 5,890,000
- Harvested for grain:
I f^ r* f\ f*\f\f*>
- Needing insecticide/
h3»biaAdc treatment:
Not known
- Actually treated at least
I . "(tift^
n 3,690,000
\J Please list the insecticides/kafibaoides (four or five) most frequently used on corn/aa»ghum in your
state, in decreasing order of volume of use.
2j Please list the most important insect s/wewts, in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop Sorghum :
Type of Pesticide: Insecticides
Year : 1974
State: Nebraska
NJ
00
Pound Active Ingredient Per Acre
Recommended
Target By Extension
Pesticide3-/ Pest(s)j>/ Service By Suppliers
Ethyl parathion greenbugs
©
Di-^yston
Diraethoate
greenbugs
greenbugs
0.5 Lb. 0.5 Lb.
H& 0.25 Lb. 0.25 Lb.
0.38 Lb. 0.38 Lb.
* applied by aircraft - not by farmers
Generally Minimum Total Acreage Versus Acreage
Used by Effective Treated with Insecticides/
Growers Rate Herbicides in the State
0.5 Lb.* BX 0.5 Lb Approximate number of acres
0.25 Lb.* 0.25 Lb.
in your state (1974) -
0.38 Lb. 0.38 Lb. - Planted: 2,Z?5,000
- Harvested for grain:
1,865,000
- Needing insecticide/
treatment:
Not known
- Actually treated at least
once
800,000 or less
sorghum in your
_!/ Please list the insecticides/he«b*«MtAa6 (four or five) most frequently used on
state, in decreasing order of volume of use.
2J Please list the most important insects/ww**6, in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Cr°P : Sorghum
Type of Pesticide: insecticide
Year : 1974
State: New Mexico
Pound Active Ingredient Per Acre
Recommended
Target By Extension
Pesticide^/ Pest(s)W
ho
NS
v£>
disulfoton B.C.
disulfoton gran
disulfoton gran
phorate gran.
phorate gran.
parathion E.G.
HiTTKaf-Vinfltp F fl.
greenbug
. greenbug
. mites
greenbug
mites
greenbug
ovppnhncr
Service
0.375-0.5
1.0
1.0
1.0
1.0
0.5
By Suppliers
0.375-0.5
0.75 - 1.0
1.0
0.75-1.0
1.0
0.5
Generally
M in imum
Total Acreage Versus Acreage
Used by Effective Treated with Insecticides/
Growers
0.375-0.5
0.75-1.0
1.0
0.75-1.0
1.0
0.5
n.-n-n.s
Rate
0.5
1.0
1.0
1.0
1.0
1.0
n.«>
Herbicides in the State
Approximate number of acres
in your state (1974) -
- Planted: 500,000-260,000 irrigated
240,000 dry land
- Harvested for grain:
225,500 irrigated 180,000 dry lam
- Needing insecticide/
- Actually treated at least
once with any insecticide/
•'• 250,000
/sorghum in your
JL/ Please list the insecticides/hmjAtmuiidms (four or five) most frequently used on
state, in decreasing order of volume of use.
2/ Please list the most important insects/w*e*s, in decreasing order of importance, against which the
listed pesticides are recommended and used.
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PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop : Apples
Type of Pesticide: Fungicides
Year : 1974
State:
MEW VOKK
w
o
Pound Active Ingredient Per Acre (or per 100 gal.)
Recommended
Pesticide!/ Pest(s)^/
By Extension
Service
By Suppliers
cap tan
dodine.
eh / z-inc
coordination
product
apple. & cab 14 appl. d 3
apple. &cab 14 appl. @ 0.73 Ib/A ?
powdeAy mildew 8 appl. @ 6 Ib/A ?
apple. Acab 14 appl. @ 4.8 Ib/k ?
6 appl. @ 1.8 Ib/k ?
be.nomyl
o-il
apple. 4 cab 14 appl. @ 0.25 £b/A ?
pou)deAy mildew 8 appl. @ 0.25 £b/A ?
(p£a6 3-4 quaAtb
oJLL pun acte.)
Generally
Used by
Growers
Minimum
Effective
Rate
Total Acreage Versus Acreage
Treated with Insecticides/
Fungicides in the State
6-14 appl. @ 1.5-3 Ib/A
Approximate number of acres
6-1-4 appl. (I
0.73 £b/A
6-8 appl. @
4-6 Ib/A
6-14 appl. §
of apples in your state
- Total 72,000
1.8 Ib/A
6-14 appl. @
0.25 £b/A
6-8 appl. @
0.25 £b/A
- Needing iiueefcteidc/
fungicide treatment: 72,000
- Actually treated at least
once with any iiTHJOl iiC-idj,/
fungicide: 72,000
jy Please list the inoeotiicid&s/fungicides (four or five) most frequently used on apples in your state,
in decreasing order of volume of use.
2J Please list the most important i«««afc£==ae4=«t*«e/diseases9 in decreasing order of importance, against
which the listed pesticides are recommended and used.
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PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop : Apples
Type of Pesticide: insecticides
Year : 1974
State:
to
u>
Pesticide3./ Pest(s)^/
Pound Active Ingredient Per Acre (or per 100 gal.)
Recommended Generally Minimum
Used by Effective
By Suppliers Growers Rate
By Extension
Service
/
it
i i
Total Acreage Versus Acreage
Treated with Insecticides/
Fungicides in the State
Approximate number of acres
of apples in your state
- Total
- Needing insecticide/
treatment:
/ **^ /
Actually treated at least
once with any insecticide/
' «*E^E :
75
/
_!/ Please list the insect icides/fju»fcie.i.4»6 (four or five) most frequently used on apples in your state,
in decreasing order of volume of use.
"ij Please list the most important insects and mite s/diM, 11011.0, in decreasing order of importance, against
which the listed pesticides are recommended and used.
or
Ct 30
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PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop : Apples
Type of Pesticide: Fungicides
Year : 1974
State: North Carolina
to
Pesticide!/ Pest(s)^/
Captan
Pound Active Ingredient Per Acre (or per 100 gal.)
Recommended Generally Minimum
Used by Effective
By Suppliers Growers Rate
By Extension
Service
scab, black
rot, white
rot, bitter
rot, sooty
blotch
maneb bitter rot,
black rot,
white rot,
scab, rusts,
sooty blotch
dodine scab
benomyl scab, black rot,
white rot,
mildew, sooty blotch
folpef black rot,
__,,_,__.white rot/
The Extension
Service makes
no recommendations.
It provides
information
Yes
2 Ib
yes
2 Ib
yes
yes
yes
1/2 Ib.
6 oz.
2 Ib.
Total Acreage Versus Acreage
Treated with Insecticides/
Fungicides in the State
Approximate number of acres
of apples in your state
- Total
- Needing
20,000
fungicide treatment: 20,000
Actually treated at least
once with any
fungicide: 20,000
_!/ Please list the insecticides/fungicides (four or five) most frequently used on apples in your state,
in-'decreasing order of volume of use." C, ' f , f <
2_l Please list the most important insect^s^jjjui mites/diseases, in decreasing order of Importanca^ against
<[_wfaich the risJ^ed^ejBtJLcides are recommended and used.--- ^ '•*—^
^~^. bitter rot,
scab, sooty blotch ~ IK
ferbam rusts (quince and cedar apple) „._
sulfur powdery mildew ves
dinocap powdery mildew yes
thiram rusts, fruit rots yes
2 Ib.
1/4 Ib.
2 Ib.
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PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop : Apples
Type of Pesticide: Insecticide
Year : 1974
state: North Carolina
Fungicide *• Miticide
Pound Active Ingredient Per Acre (or per 100 gal.)
Recommended Generally Minimum
By Extension
PesticideJ/ Pest(s)£/ Service By Suppliers
Total Acreage Versus Acreage
Treated with Insecticides/
Fungicides in the State
Guthion 50 W
Lead Arsenate
WP
Parathion 15W
Phosphamidon SE
Caotan 50 W
Polyqram RO WP
CM, RBLR, AM
CM, RBLR, AM
Diseases
CM, RBLR, AM
Aphids
Scab, Rots
Scab, Rusts
Rots
1/2 Ib
2
2
2
2
2
Ib
Ib
1/2 02
Ib
Ib
1/2 Ib
2
2
2
2
2
Ib
Ib
1/2 oz
Ib
Ib
1/2 Ib
2 - 3 Ib
2 Ib
2 1/2 oz
2 Ib
2 Ib
1/2 Ib
2
2
2
2
2
Ib
Ib
1/2 oz
Ib
Ib
Approximate number of acres
of apples in your state
- Total 1 ,110,354 trees
$13.1 million
- Needing insecticide/
fungicide treatment: Al
- Actually treated at least
1
once with any insecticide/
fungicide: All
Oil
Mites
2 gal
2 gal
2 gal
2 gal
_!/ Please list the insecticides/fungicides (four or five) most frequently used on apples in your state,
in decreasing order of volume of use.
"II Please list the most important insects and mites/diseases, in decreasing order of importance, against
which the listed pesticides are recommended and used.
-------
PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop : Apples
Type of Pesticide: Fungicides
Year : 1974
State: Ohio
to
Lo
Pesticide!/ Pest(s)^/
Pound Active Ingredient Per Acre (or per 100 gal.)
Recommended Generally Minimum
Used by Effective
By Suppliers Growers Rate
By Extension
Service
Total Acreage Versus Acreage
Treated with Insecticides/
Fungicides in the State
/? X / 1 /— 7 " r *1 Cf f
' /3 A TVi? ^7 y&MrU.rt£L l/t^f-Y^^
_ss£*- p f &** l > / /
X"' / // XI '
G.(eeode$ p
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PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
Crop :
Type of Pesticide:
Year : 1974
State
Pound Active Ingredient Per Acre
Recommended
N3
01
Target By Extension
Pesticide—/ Pest(s)W^ Service
/\ -f t**~ £\ ^ ^"/) "C
/I / / ; / r.fl- (— >****& ' ^r— "^ -^
By Suppliers
J- ^ 5
/i +<:
Generally
Used by
Growers
'1 /• ~3
Minimum Total Acreage Versus Acreage
Effective Treated with Insecticides/
Rate Herbicides in the State
^ Approximate number of acres
. '* in your state (1974) - 3. •' ^ '
.1 >. _. . ~> / /
,v/
~i/^'
- Planted: j3 . /
•"'
- Harvested for grain: <2- • "t '*'***'
- Needing inaei^LiLidL/- ^
herbicide treatment:
- Actually treated at least _ -,
i a~- • '/ '
once with any iiiDBrfinirta/
herbicide:
\J Please list the JTtsoafcAaidac/herbicides (four or five) most frequently used on corn/aofghum in your
state, in decreasing order of volume of use.
2/ Please list the most important 4w«««*K/weeds, in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
NJ
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence ~\
PESTICIDE APPLICATION DATA
Crop : Apples
Type of Pesticide: jT/vS£t fVc <«€.-
Year
State:
H /
)
1974
Recommended Generally Minimum Total Acreage Versus Acreage
By Extension Used by Effective Treated with Insecticides/
Pesticide!' Pest(s)£' Service i By Suppliers Growers Rate Fungicides in the State
fr - -K, \ * \
Ic.adlii'W VvivH \ I ; i
\ U I'll \ • r \
)Pia~ G*CuVi<9 \ ,>Llbi, \ $ \ • . I
aatt.^S*"^.^.!--. , j^ ^ ^
Approximate number of acres
of apples in your state6^;« /S'oGOyJ
- Total
^
T
*
- Needing insecticide/
fungicide treatment:
- Actually treated at least
once with any insecticide/
(rour or five) most frequently used on apples in your state,
in decreasing order of volume of use.
_2/ Please list the most important insects and mites/diciooaae, in decreasing order of importance, against
which the listed pesticides are recommended and used.
-------
PESTICIDE APPLICATION DATA
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 641LO
Attn: K. A. Lawrence
Crop So
Type of Pesticide: /
Year : 1974
State:
NJ
Pound Active Ingredient Per Acre
Recommended
Target
Pesticide!/ Pest(s)W
By Extension
Service
J-3
;-
/-
By Suppliers
1-3
Generally
Used by
Growers
Minimum
Effective
Rate
'-0.
i <=^ |>!
>. 5 * *• i
H M
rfr"l *
-' t J
" V ^
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
in your state (1974) -
- Planted: ^oo^oof)
- Harvested for grain:
"5SOj ooO
- Needing
Cjterbicidjg) treatment:
- Actually treated at least
once with any Mrteeticld
QoaooO
^/ Please list the in«e©fe*e*4&s/herbicides (four or five) most frequently used on corn/ sorghum in your
state, in decreasing order of volume of use.
2J Please list the most important iticaetif/weeds, in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
PESTICIDE APPLICATION DATA
Crop Corn :
Type of Pesticide: Herbicide
Year : 1974
State: South Dakota
Pound Active Ingredient Per Acre
N>
U>
00
Pesticide^/
alachlor
propachlor
atrazine
2,4-D
dicamba
Target
Pest(s)W
Recommended
By Extension
Service By Suppliers
Generally
Used by
Growers
Ann. grass 2-3
Ann. Broadleaved 1-3
Broadleaved %-%
Broadleaved %
Minimum Total Acreage Versus Acreage
Effective Treated with Insecticides/
Rate Herbicides in the State
Approximate number of acres
in your state (1974) -
- Planted:
- Harvested for grains
- Needing
herbicide treatments
- Actually treated at least
once with any
herbicide:
\J Please list the «wsae*&ofe£<£s/herbicides (four or five) most frequently used on corn/»e*g&*sn in your
state, in decreasing order of volume of use.
2J Please list the most important j&*3Vfo&f>/weeds, in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
PESTICIDE APPLICATION DATA
Crop Grain Sorghum?
Type of Pesticide: Herbicide
Year : 1974
State:South Dakota
Pound Active Ingredient Per Acre
NJ
OJ
VO
P p <; f i r i ri <= ^ '
2,4-D
propachlor
Target
Pest(s)b_/
Broadleaved
Ann. Grass
Recommended
By Extension
Service By Suppliers
\-h
4-5
Generally
Used by
Growers
Minimum
Effective
Rate
Total Acreage Versus Acreage
Treated with Insecticides/
Herbicides in the State
Approximate number of acres
atrazine Ann. Broadleaved 1^
propazine and grass 2
in your state (1974) -
- Planted:
- Harvested for grain:
- Needing insecticide/
herbicide treatment:
- Actually treated at least
once with any M»««*fet rr i rU
herbicide:
I/ Please list the JuJiiLJLiidiLs/herbicides (four or five) most frequently used on corn/sorghum in your
state, in decreasing order of volume of use.
2/ Please list the most important insects/weeds, in decreasing order of importance, against which the
listed pesticides are recommended and used.
-------
Return to:
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Attn: K. A. Lawrence
PESTICIDE APPLICATION DATA
Crop : Apples
Type of Pesticide: Insecticides
Year : 1974
State:
Pesticide*/ Pest(s)^/
Pound Active Ingredient Per Acre (or per 100 gal.)
Recommended Generally Minimum
Used by Effective
By Suppliers Growers Rate
By Extension
Service
5
4>l
€>
'
Total Acreage Versus Acreage
Treated with Insecticides/
Fungicides in the State
Approximate number of acres
of apples in your state
- Total
500
Needing insecticide/
fungicide treatment:
Actually treated at least
once with any insecticide/
fungicide:
^/ Please list the insecticides/fungicides (four or five) most frequently used on apples in your state,
in decreasing order of volume of use.
2/ Please list the most important insects and mites/diseases, in decreasing order of importance, against
which the listed pesticides are recommended and used.
------- |