APPLY PESTICID
IIDE FOR COMMER
U.S. ENVIRONMENTAL ...
OFFICE OF PESTICIDE PROGRAMS
WASHINGTON, D.C. 20460
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TABLE OF CONTENTS
Page
Acknowledgments 1
Preface 1
Introduction 2
Dispersal Equipment 2
Calibration 3
Pattern Testing 4
Operations 5
Protecting the Environment 6
Safety Precautions 8
1976
i
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ACKNOWLEDGMENTS
PREFACE
This guide has been developed by North Carolina
State University under U.S. Environmental Protec-
tion Agency (EPA) contract 68-01-2903. This con-
tract was issued by the Training Branch, Operations
Division, Office of Pesticide Programs, EPA. The
leader of this group effort was John H. Wilson,
Jr., North Carolina State University. Editors were
Mary Ann Wamsley, EPA, and Donna M. Vermeire,
North Carolina State University.
Contributors were:
E. A. Cancienne, Louisiana State University
Richard P. Cromwell, University of Florida
F. Farrell Higbee, National Agricultural Aviation
Association, Washington, D.C.
James L. Maxwell, President, National Agricultural
Aviation Association, Washington, D.C.
George F. Mitchell, Jr., M & M Air Service, Texas
Richard F. Moorer, U.S. Environmental Protection
Agency
Frank J. Murphey, University of Delaware
Richard Reade, Mid Continent Aircraft Corpora-
tion, Hayti, Missouri
Carrol M. Voss, Ag-Rotors, Incorporated, Gettys-
burg, Pennsylvania
R. G. Winterfeld, U.S. Department of Agriculture,
Agricultural Research Service, Yakima, Washing-
ton
Wesley E. Yates, University of California
Federal regulations establish general and specific
standards that you must meet before you can use
certain pesticides. Your State will provide material
which you may study to help you meet the general
standards.
This guide contains basic information for aerial
applicators. Other guides are available to help you
meet the specific national standards for commercial
applicators in various categories of pest control.
Because the guides were prepared to cover the entire
nation, some information important to your State
may not be included. The State agency in charge of
your training can provide the other materials you
should study.
This guide will give you information about:
• dispersal equipment,
• calibration of liquid and dry systems,
• pattern testing,
• operations, and
• environmental and safety considerations.
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INTRODUCTION
Effective aerial application requires:
• close cooperation between applicator and grower
when planning a job,
• consideration of the effects on the environment,
• consideration for the safety of people, animals,
and nontarget crops,
• correct and well-maintained equipment,
• accurate and uniform application,
• a competent pilot, and
• adherence to the planned procedure.
Limitations of aerial application are:
• need for correct weather conditions,
• difficulty in treating areas containing obstructions,
• difficulty in treating small or irregularly shaped
areas, and
• long ferrying distances.
DISPERSAL EQUIPMENT
Both fixed and rotary wing aircraft are used for
aerial application. Metering and dispersal equip-
ment on the aircraft must meter correct quantities
of pesticide formulations and deliver them uni-
formly. The equipment must be accurate so it can be
calibrated correctly.
LIQUID SYSTEMS
Liquid dispersal systems consist of:
tank,
agitation system,
pump,
piping and fittings,
filters (screens),
boom, and
nozzles.
These systems may be wind-driven or they may be
hydraulic or mechanical, powered by the aircraft
engine.
Tank—The tank should be leakproof and corro-
sion-resistant. It should have a mechanism for
emptying the contents quickly in case of emergency.
The aircraft must have a guage that measures tank
contents. The tank should be fitted with an air
vent—:a tube type or a spring-loaded flapper valve.
Agitation System—Most pesticide formulations re-
quire some form of agitation during application.
Pump—The pump system must be able to deliver
'large quantities of liquid material per unit of time.
Wind-driven pumps must have a workable brake.
Piping and Fittings—Main piping and fittings should
have a large diameter (approximately 2 inches) in
order to apply high volumes of liquids, and a smaller
diameter (approximately 1 inch) for low-volume ap-
plication. Smaller piping is adequate on helicopters
because of their slower application speed.
Filters—Correctly sized line filters and nozzle filters
(screens) will prevent nozzle clogging. Screen sizes
range from 20 to 100 mesh, according to the
size of the nozzle opening (larger mesh (20) for
larger nozzles). Screens should be located between
the tank and pump or between the pump and the
boom.
Boom—The boom supports and supplies the nozzles.
When the boom is located near the trailing edge
of the wing, clearance between control surfaces of
the wing and the boom is essential. End caps on
the boom make it easier to flush the boom and
nozzles. The boom should have a positive shut-off
valve.
Nozzles—Special nozzles are available for use in
aircraft systems. They must be equipped with an
antisiphon or nondrip check valve. Manufacturer's
specifications will guide you in your choice. A
uniform spray pattern depends on correct nozzle
placement on the boom.
The spray pattern shifts in the direction of propeller
rotation. Adjusting the distance between the nozzles
on the boom helps to correct this problem (see illus-
tration below). Placing end nozzles inboard will
prevent the wingtip vortex from trapping fine drop-
lets, causing uneven distribution and drift.
Front View of Variable Distance Nozzle Placement
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Nozzle placement on a helicopter boom may be
uniform except where the spray may hit parts of
the aircraft such as the skids. A rear section boom
is sometimes used to help keep spray off the heli-
copter. The angle of the nozzle in relation to the
direction of travel affects droplet size (see illustra-
tions below). Flight speed also has an effect on the
size of droplets.
This nozzle position
produces
coarse droplets
This nozzle position
produces
tine droplets
This nozzle position
produces
medium droplets
Not this
(spray collects
on structure)
An adjustable gate is frequently used to regulate
flow rate. It must have a tight seal when closed.
Check the gate often to be sure it is set correctly
and is not leaking.
CALIBRATION
Calibration is adjusting your equipment to apply
the desired rate of pesticide. Calibration is especially
important in aerial application, since large areas
are covered in a short time. Calibrate often to be
sure that the equipment is adjusted correctly.
LIQUID SYSTEMS
Here are the basic steps in sprayer calibration:
• Determine the acres your aircraft's system treats
per minute at the speed and height you plan to fly.
• Figure the gallons you must spray per minute to
apply the recommended rate.
• Select the size and number of nozzle tips which
will deliver the correct number of gallons per
minute at the operating pressure of your system.
Use the nozzle manufacturer's specifications as a
guide.
• Make a trial run.
• Determine the amount of chemical to add to the
tank.
ULV SYSTEMS
Ultra low volume (ULV) spraying requires a special
liquid dispersal system. Manufacturers can supply
specifications for ULV systems. Few pesticides are
labeled for ultra low volume aerial application.
DRY SYSTEMS
These systems may be used for applying dry formu-
lations such as dusts, granules, and baits. The
application equipment and the size, shape, density,
and flowability of the materials affect swath width
and pattern. The hopper must have walls steep
enough to ensure uninterrupted flow, and have a
lid that will close tightly. An agitator will keep fine
materials from bridging. The air vent should be
either a spring-loaded flapper valve or tube type.
The following example will explain these basic steps.
Your aircraft has a 300 gallon tank. The effective
swath width is 50 feet. You plan to spray at 100
mph at a height of 8-10 feet. The chemical is to
be applied at the rate of 1 pint per 3 gallons of
spray per acre. The operating pressure will be 40
psi.
• Determine acres per minute covered.
Acres per minute=
2 X swath width (ft.)X speed (mph)
In our example,
1,000
2X50X100
1,000
= 10 acres per minute
The table below will tell you the acres covered
per minute when swath width and aircraft speed
are known.
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Acres Per Minute for Various Speeds and Swath
Widths
Determine the amount of chemical to add to the
tank.
Speed
(mph)
40
50
60
70
80
90
100
110
120
Swath Width (Feet)
30
2.4
3.0
3.6
4.2
4.8
5.4
6.0
6.6
7.2
35
2.8
3.5
4.2
4.9
5.6
6.3
7.0
7.7
8.4
40
3.2
4.0
4.8
5.6
6.4
7.2
8.0
8.8
9.6
45 50 75 100 200
3.6 4.0 6.0 8.0 16.0
4.5 5.0 7.5 10.0 20.0
5.4 6.0 9.0 12.0 24.0
6.3 7.0 10.5 14.0 28.0
7.2 8.0 12.0 16.0 32.0
8.1 9.0 13.5 18.0 36.0
9.0 10.0 15.0 20.0 40.0
9.9 11.0 16.5 22.0 44.0
10.8 12.0 18.0 24.0 48.0
Chemical per tank = acres per tank X chemical
recommended per acre
Determine gallons per minute (gpm) required.
In our example, 3x10 = 30 gallons per minute.
Be sure your pump can deliver this volume.
Select the nozzles.
First determine the gpm per nozzle that would
deliver the required 30 gpm flow. Most agri-
cultural aircraft booms can accommodate aboul
40 nozzles, but most applicators prefer to use the
smallest number that will provide a uniform pat-
tern. Let's assume you choose to use 26 nozzles.
The gpm per nozzle is determined this way:
gpm required
gpm per nozzle=—
number of nozzles
30
In our example, —=1.16 gpm per nozzle
26
You chose a pressure of 40 psi. Using the manu-
facturer's catalog, select a nozzle delivering 1.16
gpm at 40 psi. You may find that the nozzle
closest to your needs delivers only 1.10 gpm.
This small difference can be adjusted by increas-
ing the pressure.
• Make a trial run to check the system.
After installing 26 of the selected nozzles, make
a trial calibration test flight to be sure you are
spraying at the correct rate.
Fill the tanks with water to a known level on a
level apron or strip. Fly the aircraft at the selected
100 mph air speed and at the selected pressure
for a timed period (60 seconds in this example).
Bring the aircraft back to the same point and
measure the amount of water needed to refill the
tank to the original mark. Divide the number of
gallons used by the number of acres (10 in this
example) treated to determine the gallons you
are spraying per acre.
Acres per tank =
In our example,
gallons per tank
gallons per acre
300 gallons per tank
3 gallons per acre
100 acres per tank
100 acres per tank XI pint per acre =100 pints
(12.5 gallons) per tank
DRY SYSTEMS
Make several test flights with the spreader installed
to determine the quantity of material metered out
for a given gate setting. Helicopters may use elec-
tric or hydraulic air blowers and the material can
be caught and measured while running up on the
ground. You should use inert (blank) granules of
the same size and density as those in the formula-
tion to be applied. Operate the spreader for a
measured period of time (at least 30 seconds).
Weigh the quantity needed to refill the hopper.
It may take three or more trial gate settings to
determine the one that will give the required dis-
charge in pounds per minute of granular material.
To find the pounds per acre being applied, divide
the pounds per minute by the acres per minute.
PATTERN TESTING
Check the swath pattern to make sure the distribu-
tion across the swath is as uniform as possible.
Both helicopters and fixed-wing aircraft create wind
currents (vortices) that affect the swath pattern. The
tests must duplicate the airspeed, height of flight,
spray pressure, and nozzle angle and placement or
gate settings that will be used for the actual appli-
cation. Make pattern tests in. calm air (winds less
than 3 mph) to avoid distortion caused by cross-
winds. The best way to test a liquid pattern is to
add a tracer (dye or fluorescent material) to the
water in the tank(s) of the aircraft. For dry pattern
testing, use a blank (nontoxic) material with prop-
erties similar to the formulation to be applied. Col-
lect the test material on paper (for liquids) or in
buckets (for dry materials) placed across the flight
path on the ground. Observation of the collected
materials will show the actual swath pattern.
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A rectangular pattern gives perfect distribution if
flight swaths are spaced perfectly. The trapezoidal
and tsiangular patterns are better, however, because
they allow for some error in spacing swaths. They
give uniform distribution across the field except for
the first and last swaths.
Ideal Swath Patterns
I III II
I'll!
1
jjjjj
Rectangular
pattern
^
~~i r~
n
~i
gives perfect but is poor
distribution with
with perfect imperfect
~\ /
Trapezoidal
pattern
^ "
/
spac
~x;;
:ing
~_-*<~
s
V
pacing,
^
\
also gives perfect and less
distribution variation
with perfect with
spacing imperfect
~~~- ^
Triangular
pattern
,-'•
S
pacinc
J.
^^
also gives perfect and less
distribution variation
with perfect with
spacing imperfect
spacing.
OPERATIONS
GENERAL
When an aircraft has been calibrated, the airspeed,
spraying pressure (or gate setting for dry materials),
height of flight, and effective swath width are fixed.
Applications must be made at the same settings.
PRESSURE
Pressure should be around 40-50 psi (pounds per
square inch). Choose the pressure near this range
that will combine with your selected swath width,
airspeed, and nozzle type to give the correct rate
of application and desired droplet size. With most
nozzle types, droplet size decreases as pump pres-
sure increases. Use pressure gauges to indicate
boom or pump pressure.
FIELD FLIGHT PATTERNS
For rectangular fields, fly back and forth across the
field in parallel lines. Flying parallel to the long
axis of the field will reduce the number of turns. For
pilot safety, start treatment on the downwind side
of the field if there are low-speed crosswinds. This
prevents flying through the previous swath. (See
diagram below.) To prevent skips and drift, stop
flying if wind speed increases excessively.
Wind
Direction
If the area is too rugged or steep for this pattern,
flight lines should follow the contours of the slopes.
When the area is too steep for contour work, make
all applications downslope.
SWATH MARKING
Swaths can be marked with permanent or semi-
permanent flags set above the height of the crop to
guide the pilot. This method is useful if the field
will be treated several times a season.
Two flagmen can help the pilot line up on the field.
When the pilot has lined up on his swath, the nearer
flagman starts pacing off (or counting crop rows) to
the next swath. Flagmen should avoid being directly
sprayed on, and they should never turn their backs
toward an oncoming aircraft. When the aircraft is
being flown parallel to a row crop, one flagman can
identify the swath row for the pilot.
Automatic flagmen are often used. These devices,
attached to the aircraft and controlled by the pilot,
release weighted streamers. The streamers give the
pilot a visible mark to help him judge the next
swath. Helicopters on small field applications may
not need flagmen. Their short turnarounds allow
them to locate the next swath easily.
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TURNAROUND
At the end of each swath, the pilot should shut off
the dispersal equipment and pull up out of the field
before beginning his turn. Complete the turn soon
enough to permit slight course corrections before
dropping into the field again for the next s\vath. (See
diagram below.)
Strong downwash
and vortices area
Shut off here
Proper Turnaround
Wind
Direction
Strong downwash
and vortices area
-*-Wind—
Start here
Wind —
Shut off here
OBSTRUCTIONS
-Wind —
Adjust distance to compensate for drift
If there are obstructions (trees, power and tele-
phone lines, or buildings) outside the field at the
beginning or end of the swath, turn the equipment
on late or shut it off early. When the field is com-
pleted, fly one or two swaths crosswise (parallel to
the obstruction) to complete the job.
Obstructions inside the field should be treated in
the same way. Skip the area around the obstruction
and spot treat it later.
Areas next to buildings, residences, livestock, non-
target crops, or waterways should be treated with
caution:
• Fly parallel to the sensitive area.
• Leave a border of untreated crop to avoid
possible drift onto the area.
• Avoid making turns over dwellings where pos-
sible.
PROTECTING THE
ENVIRONMENT
CONTROLLING DRIFT
Drift is the airborne movement of spray, granule,
or dust particles to places other than the target
area. Properly controlled .drift may help the pesti-
cide reach the target. Drift is harmful when it
causes damage in nontarget areas.
The main factors that must be considered in con-
trolling drift are discussed below.
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Droplet Size
Weather
Droplet size is one of the most important factors
affecting drift. Small droplets are a much greater
drift hazard than large droplets. They stay in the air
longer because they fall more slowly, and they are
more easily carried by wind currents because they
are lighter.
Pesticide spray systems cannot produce a com-
pletely uniform droplet size. Rather, they produce a
range of droplet sizes.
Nozzle type and pressure are important factors af-
fecting droplet size. In general, the size of droplets
decreases as the size of the nozzle opening de-
creases or the pressure increases.
The position of nozzles on the boom also affects
droplet size. (See equipment section.)
You can get chemical adjuvants which affect drop-
let size:
• Thickening agents may be added to spray mix-
tures to create larger spray particles. However,
the airstream may break these large droplets into
smaller ones.
• Surfactants are sometimes added to spray solu-
tions to create smaller droplets, improve coverage,
and increase wettability of the spray. Be sure that
droplets are not so small that they create a drift
problem.
A measurement of nozzle performance is the Volume
Median Diameter (VMD) of the droplets it produces.
The VMD is the droplet diameter that satisfies the
condition that half of the spray volume consists of
drops larger, and half consists of drops smaller.
Drift Distance of a 2.8% Oil/Water Emulsion
Applied During Strong Temperature Inversion at
Boom Height of 5 Feet and Wind Speed Less
Than 5 mph.
Final VMD
(micrometers)
400
200
100
50
Distance Downwind
(feet)
50
150
400
1320 (V4 mile)
A pesticide applicator is concerned mainly with the
weather in the immediate area of application and
less than 1,000 feet from the ground. The weather
in this small area has a major effect on the pesti-
cide application, including the chance for drift
problems. Wind is an important weather factor af-
fecting drift. Stop at once if wind increases exces-
sively during application.
Other important factors are
"lapse". These terms refer to
change from the ground upward.
"inversion" and
the temperature
An inversion layer exists in still air that:
• is coolest at the ground level,
• gets warmer up to a certain height, and
• gets cooler from that point on up.
Particles released into the cool air layer at ground
level during an inversion have a minimum upward
movement. The slightest air movement can cause
this mass of particles to drift for great distances
before they fall.
A lapse exists when the air:
• is warmest at ground level, and
• gets continuously cooler at higher elevations.
During a strong lapse, the warm air near the ground
rises, carrying very small pesticide particles with it.
An applicator should at least be aware of these two
conditions, because sometimes they can be severe
enough to cause serious drift problems.
Vaporization
Another type of pesticide movement is called vapor-
ization (vapor drift)—the volatilization of an active
ingredient during or after application. You must
know which pesticides are highly volatile (evaporates
easily). High temperatures or other climatic con-
ditions may cause vaporization of some active in-
gredients. Apply them during periods of relatively
low temperature and high humidity. Use" active in-
gredients with low volatility where vaporization
might cause problems.
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Protecting Bees
Honey bees and other beneficial insects can be
harmed by some pesticide applications. Beekeepers,
aerial applicators, and their customers must coop-
erate closely to protect honeybees. You can reduce
bee losses significantly by careful planning and good
communications. Bees travel for long distances, so
use of pesticides toxic to bees may affect hives out-
side the immediate vicinity of the treatment area.
When using materials hazardous to bees, remind
your customer to notify the beekeeper so that he may
protect his bees. With few exceptions, dusts may be
more hazardous to bees than sprays. Time of appli-
cation is important and depends on blooming period
and attractiveness of the crop. Treatment during
the night and early morning before bees are forag-
ing are the saf-est for the bees.
SAFETY PRECAUTIONS
GENERAL PRECAUTIONS
• Wear protective clothing and equipment appro-
priate for the pesticide. The label on each pesti-
cide specifies the protection required.
• Know the pesticide being applied and how to get
emergency help if needed.
• Avoid all unnecessary contact with spray or dust.
• Change clothing and bathe after each day's work.
PILOT
• Avoid loading or handling highly hazardous pesti-
cides. Exposure to toxic pesticides could cause
illness that would make it unsafe to operate the
aircraft.
The signs and symptoms of illness commonly
include dizziness and constriction of the pupils of
the eyes (myosis). Myosis impairs visual sharp-
ness and can lead to fatal accidents. Direct eye
contamination by organophosphate or carbamate
pesticides may cause constriction of the pupils for
up to 7 to 10 days without any other symptoms. A
pilot who has experienced any symptoms of pesti-
cide poisoning should not fly until he has had
medical clearance.
• Make preflight aircraft check.
• Check operation and calibration of dispersal
equipment periodically.
• Check target area and surroundings for safety or
drift hazards before application.
• Avoid flying through drift.
• Do not apply pesticides over flagmen or other
persons. Use of permanent markers and auto-
matic flagmen eliminates the possibility of harm
to flagmen.
• See that members of the ground crew know their
responsibilities and are acquainted with label pre-
cautions.
• Do not fly in a manner or at a time which may
create a hazard—even if customer insists.
• Warn all people in the treatment area about the
application.
GROUND CREW
• Close tanks and hoppers tightly after filling.
• Remove any spilled chemical.
• Clean aircraft, especially the cockpit, frequently.
• Where possible, clean equipment on a hard-
surfaced apron so that runoff can be collected
and disposed of safely.
• Do not stand in runoff water without appropriate
protection or allow it to splash on you.
FLAGMEN
• Warn all people in the treatment area about the
application.
• When the aircraft is lined up for a pass, move
over to the next position.
• Do not turn your back on an approaching aircraft.
• Stay at the field until the pilot has completed the
job so you can help if an accident occurs.
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