ANALYSIS OF SPECIALIZED PESTICIDE PROBLEMS
INVERTEBRATE CONTROL AGENTS-EFFICACY TEST METHODS
VOLUME II
FOLIAR TREATMENTS II
(FIELD CROPS, FORAGE CROPS, RANGELAND,
VEGETABLES-FIELD AND GREENHOUSE)
.
JANUARY
1977
EPA-540/10-77-008
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REPORT To THE
ENVIRONMENTAL PROTECTION AGENCY
ANALYSIS OF SPECIALIZED PESTICIDE PROBLEMS
INVERTEBRATE CONTROL AGENTS - EFFICACY TEST METHODS
VOLUME II
FOLIAR TREATMENTS II
(FIELD CROPS., FORAGE CROPS, RANGELAND,
VEGETABLES - FIELD & GREENHOUSE)
The work upon which this publication is based was performed in
whole or in part under Contract No. 68-01-2457 with the Office of
Pesticide Programs, Environmental Protection Agency.
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Report To The
Environmental Protection Agency
By The
American Institute of Biological Sciences
Arlington, Virginia 22209
EPA REVIEW NOTICE
This Report has been reviewed by the Office of Pesticide Programs,
Criteria and Evaluation Division, and approved for publication.
Approval does not signify that the contents necessarily reflect
the views and policies of the Environmental Protection Agency, nor
does mention of trade names or commercial products constitute
endorsement of recommendation for use.
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FOLIAR TREATMENTS II • TASK GROUP
(Field Crops, Forage Crops, Rangeland, Vegetable - Field
Greenhouse)
Chairman:
PR. WV J. LEP8ETTER
Auburn University Extension
PR. EPWARP J. ARMBRUST
Illinois State Natural History Survey
PR. ELLIS W. HUPPLEST0N
New Mexico State University
PR. ROV HALE
Owen T. Rice
Son
PR. JOHN C. OWENS
Pioneer Hybrid International Co.
PR. RICHARP N. HOFMASTER
Virginia Truck Experiment Station
PR. FLOyp SMITH
USDA-Agricultural Research Service
PR. PAl/IP L. WATSON
Velsicol Chemical Corporation
EPA Observer:
MR. ROGER PIERPONT
Criteria and Evaluation Division
AIBS Coordinators:
MS. PATRICIA RUSSELL
MR. PONALP R.'BEEM
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FOLIAR TREATMENTS II
(Field Crops, Forage Crops, Rangeland,
Vegetables - Field & Greenhouse)
Table of Contents
Page
Introduction 1
General Methods 2.
Field Crops 6
Corn 6
Southwestern Corn Borer 8
European Corn Borer 8
Corn Earworm 9
Fall Armyworm, Beet Armyworm, Corn Earworm 10
Corn Rootworms (adults) ..... 10
Cotton 11
Boll Weevil 11
Bollworm and Tobacco Budworm 13
Lygus 15
Mites 17
Pink Bollworm 18
Sorghum 21
Greenbug 21
Sorghum Midge 23
Banks Grass Mite . 24
Soybeans 25
Podworm, Stinkbugs and Defoliating Insects 25
Mexican Bean Beetle and Bean Leaf Beetle 27
Southern Green Stinkbug 29
Sugar Beets 30
Beet Armyworm and Fall Armyworm 30
Sugarcane 32
Sugarcane Borer ..... 32
Sunflowers 34
Sunflower Moth 34
Tobacco 36
Tobacco Budworm, Tobacco Hornworm and Cabbage Looper 36
Green Peach Aphid and Tobacco Flea Beetle 38
Wheat 39
Greenbug 39
Winter Wheat 40
Pale Western Cutworm 40
Forage Crops 42
Alfalfa Weevil and Egyptian Alfalfa Weevil 42
Weevil Parasites 45
Spittlebugs 46
Potato Leafhopper 47
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Table of Contents (Continued)
Page
Aphids 47
European Chafer, White Grubs, Clover Root Borer, Sitona Species . 47
Seed Chalcids and Plant Bugs • 48
Rangeland •
Grasshoppers •> 49
Range Caterpillar 52
Harvester Ants 54
Imported Fire Ant • 56
Black Grass Bugs 58
Chigger (affecting Turkeys) 59
Vegetables (Field Grown) 62
Cruciferae 62
Cabbage Looper (#1) . 62
Harlequin Bug 65
Flea Beetles 66
Cruciferae and Head Lettuce 68
Aphids and Thrips 68
Cabbage Looper (#2) . 71
Cucurbits ......... 73
Cucumber Beetles 73
Squash Bug 76
Squash Vine Borer 77
Pickleworm and Melonworm 77
Melon Aphid 78
Cabbage Looper 78
Mites ' 79
Irish Potatoes ..... 80
Colorado Potato Beetle 80
Potato Flea Beetle 83
Potato Leafhopper and Other Leafhoppers 83
European Corn Borer 84
Potato Psyllid 85
Aphids 86
Potato Tuberworm 87
Lettuce 89
European Lettuce Root Aphid 89
Lima Beans 91
Lygus Bug 91
Peas 93
Pea Aphid 93
Pea Weevil 95
Peppers 96
European Corn Borer 96
Green Peach Aphid (#1) . 98
Pepper Maggot 99
Green Peach Aphid (#2) 100
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Table of Contents (Continued)
Page
Snap Beans, Lima Beans and Southern Peas 101
Mexican Bean Beetle 101
Bean Leaf Beetle 103
Bean Aphid 103
Cowpea Curculio . . . ; 103
Leafhoppers 104
Sweet Corn 105
Corn Earworm . 105
Fall Armyworm 106
Corn Flea Beetle 107
European Corn Borer 108
Tomatoes 110
Tomato Fruitworm 110
Colorado Potato Beetle Ill
Potato Flea Beetle Ill
Aphids 112
Tomatoes, Poled 113
Tomato Fruitworm and Tomato Pinworm 113
Vegetables (Greenhouse) 115
Aphids 117
Beetles 118
Cutworms 119
Garden Symphylan 120
Greenhouse Whitefly 123
Leafminer 125
Leaf Eating Caterpillars 128
Slugs and Snails 130
Spider Mites 133
Tomato Pinworm 135
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INTRODUCTION
The primary purpose in testing new insecti .des and acaricides in foliar
applications to various crops is to establish their effectiveness and usefulness.
This report is concerned with testing chemicals in foliar applications to field
crops, forage crops, rangeland, and vegetable crops (field and greenhouse), to
establish their efficaciousness in protecting these crops from economic injury
by insects and mites. In addition, test methods should take into consideration
environmental involvement from such applications and the effect of pesticides on
beneficial organisms. Test methods should be broad enough to provide information
on the use of dosages of pesticides often required for pest population regulation
in integrated pest management systems.
Foliar applications of insecticides and acaricides are usually made at
recommended periods for control of the pest or pest complex present on the crop,
normally during a period of pest population increase. Initially, test materials
should be applied alone rather than in combination with other ingredients such as
fungicides to permit evaluation of independent effects. Application equipment
and methods employed should give adequate and reasonably uniform coverage approxi-
mating field practice. Test materials should be in one or more of the commercial
type formulations such as wettable powder, emulsifiable concentrate, ULV, etc.
It is preferable to apply pesticides at three or more dosages approximating minimum
and maximum rates. Initially, new pesticides should be tested in small, replicated
field plots to permit statistical evaluation of results. Large scale field trials
approximating commercial use, preferably replicated, and compared with a standard
treatment should be conducted to determine practicability and compatibility with
the environment. Any auxiliary spray materials including spreaders and stickers
used in combination with test chemicals should be named and used according to
manufacturers recommendations.
The methods described herein are not to be considered exclusive of other
methods. Certain situations may require special methods, and new methods may be
developed which improve on present ones. With some pests several acceptable
methods of evaluating pesticides are available, but only the more common ones are
presented. The suggested methods are purposely kept broad to cover the wide range
of conditions which may be encountered in the diverse climatic, pest and cultural
conditions of different growing regions. More specific information may be obtained
by referring to the literature citations.
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GENERAL METHODS
The following general methods are appropriate for the evaluation of the
efficacy of chemical pesticides in foliar applications (for certain pests,
applications to other p^arts of the plant and/or soil in which they grow) to:
(1) Field Crops, (2) Forage Crops, (3) Rangeland, (4) Vegetables (Field Grown),
and (5) Vegetables (Greenhouse). Specific variations to these methods are
identified throughout the report under the individual pest or pest group in each
section.
Small Scale Field Tests
Pesticides in the early stages of development (prior to establishment of an
experimental tolerance) are usually tested on small, replicated plots to develop
a wide range of information on performance and phytotoxicity. Small plots are
used to insure thorough and uniform coverage of the plants, and to minimize the
crop contaminated with experimental^materials. Crops treated with materials in
this stage of development must normally be destroyed, following completion of the
tests.
Crop and Location of Tests:—Plants should be a uniform size and vigor, and
plant size and planting distance should allow separation into units which may be
treated separately. Varieties chosen should be typical of those common to the
area. Pest density and stage of development should be relatively uniform through-
out the test site. Preferably the pest population should be increasing at the
time of treatment.
Plot Size and Design:—These will vary somewhat with the individual pests,
but a minimum of 3 replicates per treatment should be used where uniformity occurs.
The number of replicates should be increased where plant age, variety, rootstock,
plant vigor or pest populations vary. The use of randomized blocks, latin squares
or split blocks is desirable for later analysis of results. In some situations
it may be desirable to use buffer plots around the test plots to minimize drift
from treatment of adjacent plots.
Applications and Equipment;—Apply at recommended periods for best control
of the pest or pest complex. The experimental materials should be applied alone
initially rather than in combination with other ingredients such as fungicides
so that their independent effects may be evaluated. Apply test materials with
equipment and methods generally known to give adequate and uniform coverage
approximating that in field use, and appropriate to the pest and crop involved.
Apply the test materials in one or more of the commercial type of formulations,
such as wettable powder, emulsifiable concentrate, ULV, etc. The pH can affect
the performance of a pesticide and should be given due consideration.
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The selection of a dosage will depend on available data but it is preferable
to apply materials at two or more dosages approximating minimum and maximum rates.
Where practical, both a standard treatment (one which has a background of informa-
tion on its performance) and an untreated check plot should be included for com-
parison with experimental materials.
The number of trials with each candidate pesticide will vary considerably,
but an adequate number of trials should be conducted to permit accumulation of
data on: (1) Timing and dosage for best control; (2) Performance on various pest
densities and stages; (3) Phytotoxicity to various cultivars at different growth
stages; (4) Effects on non-target species; and, (5) Effects of weather on performance.
Equipment should be thoroughly cleaned before and after each use. Between
each treatment, the entire spray system should be operated with water (or a com-
patible substitute) until only clear water is sprayed. If two or more rates of the
same formulation of the same pesticide are used, begin the application with the
lowest rate in order to minimize contamination.
Sampling;—Sampling methods, counting methods, methods of presenting results
including yields and, in certain cases, plot size and design will differ with
specific pests or pest groups and will be discussed under the individual pest or
pest group.
Analysis and Reporting of Data;—If a question of relative effectiveness of
treatments occurs, an analysis of variance and multiple range test or other appro-
priate statistical analysis should be conducted to determine the statistical
reliability of the differences between treatments. If treatment means alone are
provided, they should be accompanied by the standard deviation.
The following information should be included when reporting test results:
Name and address of investigator.
Product name and formulation used, indicating active ingredient.
Crop (variety) treated.
Location of the test [soil type (if applicable) and soil moisture].
Type irrigation used (furrow or sprinkler).
Plot size.
Number of replications.
Rate of application - a.i. per hectare.
Finished spray volume per hectare.
Method of application (type of equipment, type of spray, coverage).
Stage of crop growth.
Treatment dates.
Harvest date.
How samples were taken.
Number of samples taken.
Percent infestation.
Percent control.
Phytotoxicity (type and degree of).
Comments regarding unusual test conditions or performance.
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Temperature and general weather conditions at time of treatment.
Rainfall or any unusual weather after the treatment.
Include comment on performance as related to commercial acceptability (in"
eluding effects on yield).
Statistical analysis.
References:—Pertinent references are cited.
Large Scale Field Tests
By the time a pesticide receives a temporary or experimental tolerance or
an exemption from a tolerance, several small scale field tests have been conducted
and a considerable amount of data has been collected on efficacy, phytotoxicity
and effects on non-target organisms. It is then desirable to observe its perfor-
mance under typical commercial conditions.
Crop and Location of Tests:—Several field plots should be selected which are
representative of varieties, ages of plants, cultural practices and pest populations
which are commonly encountered throughout the area.
Plot Size and Design:—Plots suitable in size for commercial application
should be used. These should have dimensions large enough to avoid drift problems.
Application and Equipment:—Compounds reaching this stage of development should
be tested under a range of application techniques. This should include dilute and
concentrate air-carrier applications, and aerial application if this method is to
be used commercially. The test material may be combined with other commonly used
agricultural chemicals to substantiate any previous compatibility information.
The formulation and dosage used should be consistent with probable commercial
use in the area. The experimental pesticide should be compared with a standard
treatment applied to an adjacent area of the planting. Where possible, comparison
with a small, untreated check plot is desirable.
The number of trials will vary somewhat with the pest and how readily infesta-
tions may be found; however, 3 to 5 large-scale trials are usually adequate.
Equipment should be thoroughly cleaned before and after each use. Between
each treatment, the entire spray system should be operated with water (or a compatible
substitute) until only clear water is sprayed. If two or more rates of the same
formulation of the same pesticide are used, begin the application with the lowest
rate in order to minimize contamination.
Sampling:—Sampling methods, counting methods and methods of presenting results,
including yields, will differ with specific pests or pest groups and will be pre-
sented under each pest or pest group.
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Analysis and Reporting of Data;—Analysis" of the results of large-scale field
trials may not be practical because of the lack of true replication.
See small scale field tests for reporting of data.
References:—Pertinent references are cited.
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FIELD CROPS
CORN, Zea mays L.
The following general parameters are applicable to the testing of
insecticides for efficacy on corn, Zea mays L. Following this section, there
are additional suggested guidelines for evaluating foliar insecticides for the
control of specific insect pests of corn.
Crop and Location of Tests:—The corn variety selected must be agronomically
adapted for the specific growing conditions experienced in the geographical
location of the test site. The corn variety should be susceptible to feeding
by the test organism (e.g., insect, mite).
The field, or test site within the field, should have uniform growing
conditions (e.g., soil type and available moisture). A single corn variety should
be utilized throughout the test plot. If large-scale plots preclude a single
variety for the entire test site, a single variety must be utilized within each
block of the experimental design. Uniformity of corn varieties is necessary to
avoid masking of treatment effects through significant variety X invertebrate
preference interactions.
Natural or artifical infestations of the test invertebrate may be used
depending upon the specific conditions of the experiment. Extreme care must be
exercised to ensure that laboratory reared invertebrate pests retain their
preference for the host plant rather than prefer an artifical diet. The entire
test site should be protected from pesticide drift originating from commercial
applications of pesticides on adjoining fields.
The minimum plot size for small-plot ground equipment or high clearance
sprayers is 3-4 rows x 15m (ca. 50 ft,). When using minimum plot size, data must
be collected only from the center row(s) in order to minimize the effect of
pesticide drift from adjoining plots. Because of the danger of drift in small
plots, surface winds must be monitored closely and spraying must cease when
pesticide drift is likely to mask treatment effects. When pesticide drift is
unavoidable, plot width and length must be sufficiently large enough to eliminate
drift into that portion of each replication (block) from which data will be collect-
ed.
Minimum plot size for aerially applied pesticides is 3 swath widths x 300 m
(ca. 1000 ft.). Data should be collected only from the center 2 rows of the middle
swath in order to minimize drift effect from adjoining plots. The two remaining
swaths will serve as buffer zones. Surface winds often cause aerially applied
pesticides to drift great distances. When using minimum plot size, spraying
should cease when surface winds cause the pesticides to drift past the two buffer
zones and into the middle swath. When drift is unavoidable, plot size must be
increased to a size large enough to eliminate drift into that portion of each swath
from which data will be collected.
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Experimental Design:—A randomized complete block is the most widely used
experimental design for evaluating pesticides against foliar arthropod pests of
corn.
A minimum of three replications of treatments should be employed for either
ground or aerially applied pesticides at a single location. When the same
experiment is conducted at two or more locations, two replications of treatments
at each location will yield valid experimental results if the data are analyzed
in a combined analysis of variance. Three or more replications are needed,
however, if single locations are to be analyzed individually. Generally it is
desirable to test at several locations (environments) and to utilize different
corn varieties in order to detect treatment x environment interactions, treatment
x variety interactions, and treatment x variety x environment interactions.
Untreated controls and the recognized standard insecticide trea'tment(s)
should be included in each replication (block) of the experimental design to
provide bases of comparison. When it is impossible to have untreated controls
because of the large acreage involved, it should be sufficient to compare the
treatments with one or more acceptable standards.
Application and Equipment:—Equipment should be thoroughly cleaned before and
after each use. Between each treatment, the entire spray system should be operated
with water (or a compatible substitute) until only clear water is sprayed. If two
or more rates of the same formulation of the same pesticide are used, begin the
application with the lowest rate in order to minimize contamination.
Many of the organic phosphate insecticides breakdown rapidly in alkaline
water (pH above 7.0). A testing kit can be used to determine the pH of the water
supply and, in cities, this information is available from the water department.
At the initial testing stage, 2-3 rates should be applied. When an optimum
rate has been established and testing is in the final stages of product development,
then the optimum rate should be used.
The finished spray volume per hectare (acre) varies with crop growth stage
and application method. 5-47 1/ha (ca. 0.5-5 gal/acre) usually are applied by air.
Higher volumes can be applied by modification of the aircraft spray system.
95-568 1/ha (ca. 10-60 gallons/acre) are usually applied by ground equipment,
such as small-plot sprayers and high-clearance sprayers. Higher volumes can be
applied if necessary.
Analysis of Data:—Data should be subjected to analysis of variance and if
significant differences are detected, multiple comparisons of treatment means
should be conducted with a seperation test such as Duncan's Multiple Range or
Tukey's Test.
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Southwestern Corn Borer, Diatraea grandiose11a (Dyar)
The stem of the corn plant is internally girdled by the 2nd generation larvae
of this insect causing stem breakage and harvesting problems.
The stage of crop at application should be whenever the 2nd generation eggs
are oviposited in sufficient quantities to warrent treatment, usually tassel and
silk stages.
The stage of insect at application is the egg or early larval stage.
The intervals between application are 7 to 15 days, until oviposition ceases.
Sampling:—Dissect 10 plants from each treatment in each replication (block)
for number of feeding tunnels of 2nd generation borers.
Examine plants from each treatment in each replication (block) for stalk
girdling and record as percent girdling estimates.
Obtain yield samples at physiological plant maturity by manually harvesting
at least 0.0004 ha (0.001 acre) from each treatment in each replication (block).
If mechanical equipment is used, recheck each harvested plot for dropped ears
due to insect feeding and record as percent of harvested ears.
Harvested ears should be examined individually for southwestern corn borer
damage.
References
Arbuthnot, K.D., and R.R. Walton. 1954. Insecticides for control of the
southwestern corn borer. J. Soon. Entomol. 47:707-708.
Keaster, A.J. 1972. Evaluation of insecticides for control of the southwestern
corn borer in Southeastern Missouri 1967-1969. J. Eoon. Entomol. 65:563-566.
European Corn Borer, Ostr-in-la nub-Halis
Leaves are damaged by larvae feeding in the whorl; tunnelling is seen in the
stalk; stalks break, ears fall due to feeding in the ear shank. Earlier generation
larvae destroy food-conducting vessels with consequent weakening of the plant, re-
duction of ear size and weight, of number of grains and grain weight. Later
generation larval cause loss of ears due to ear dropping and harvest efficiency is
reduced.
The stage of the crop at application should be whenever eggs are oviposited
in sufficient quantities to justify treatment. Artificial infestation of eggs should
be timed so as to properly coincide with natural oviposition. Usually early
whorl stage for first generation and tassel to silk stages for second generation.
The stage of insect at application is the egg or early larval stage.
Often only one application is made, a second application may be made 7-10 days
following the first application.
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Sampling:—Evaluation procedures for the leaf-feeding first-generation borer
consist of a visual plant rating scale of 1-9 (l=little or no feeding damage and
9=highly damaged) for at least 10 randomly selected plants from each treatment
per replication (block).
Stalk evaluations are made for the second generation borer and at least 10
plants from each treatment per replication (block) are dissected for number of
feeding tunnels.
Yield samples are obtained at physiological plant maturity by manually
harvesting at least 0.0004 ha (0.001 acre) from each treatment in each replication
(block). If mechanical harvesting equipment is used, recheck each harvested plot
for dropped ears due to borer feeding and record as percent of harvested ears.
Harvested ears should be examined individually for European corn borer damage.
References
Berry, E.G., J.E. Cambell, C.R. Edwards, J.A. Harding, W.G. Lovely, and G.M.
McWhorter. 1972. Further field test's of chemicals for control of the
European corn borer. J. Eoon. Entomol. 65:1113-16.
Cox, H.C., and T.A. Brindley. 1958. Time of insecticide application in European
corn borer control. J. Eoon. Entomol. 51:133-7.
Harding, J.A., W.G. Lovely, and R.C. Dyar. 1968. Field tests of chemicals for
control of the European corn borer. J. Eoon. Entomol. 61:1427-30.
Corn Earworm, Eeliothis zea
The principal damage is caused by larval feeding in the corn ears resulting
in loss of kernels primarily at the distal end of the ear and secondary contamina-
tion of the ear by pathogenic organisms. The larvae also may occasionally feed as
budworms in the whorl of the corn plant causing destruction of leaf tissue. Usually
it is not economically feasible to treat field corn for corn earworm control.
If adult moths are present and ovipositing, the first application should be
made at silking or 2-3 days prior to silking, or when 7-10% of the ears are silking.
The stage of insect at application is the egg or early larval stage.
Applications may range from as often as once every 24 hours to once every 3
days until the silks turn brown.
Sampling:—United States Standards for U.S. fancy grade fresh sweet corn per-
mit no more than 10% damaged ears from all sources. The most common method of
collecting corn earworm infestation data is to examine 10 or more individual ears
from each treatment per replication (block) at harvest. Data are recorded as
percent of injury-free ears, percent of worm-free ears, or percent of worm-infested
ears.
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RefeTenoes
Janes, M.J., and G.L. Greene. 1972. Corn earworm control on sweet corn ears in
Central and South Florida, 1969-70. J. Boon. Entomol. 65:521-522.
Keaster, A.J. 1969. Corn earworm control on sweet corn in Southeastern Missouri,
J. Eoon. Entomol. 62:1513-14.
Fall Armyworm, Spodoptera fruqiyerda, Beet Armyworm, S. exiqua, Corn Earworm,
Eelioth-is zea
These insects feed in the whorl of the corn plant causing severe destruction
of leaf tissue and occasionally migrate to the ears when the plants tassel. The
principal budworm is the fall armyworm with beet armyworms and corn earworms some-
times present.
The stage of the crop at application is early whorl to tassel. The degree of
control on whorl stage corn is not so important as for the ears.
The stage of insect at application is early to mid-larval stages.
Applications range from 2-22 with intervals ranging from 2-11 days apart.
Sampling:—Counts of at least 10 randomly selected corn plants are made in
the center of each treatment per replication (block). The results are expressed
as percent of injury-free or worm-infested plants. Observations are made from
1-7 days after the last insecticide application.
Reference
Greene, G.L., and M.J. Janes. 1970. Control of budworms on sweet corn in
central and south Florida. J. Econ. Entomol. 63:579-582.
Western Corn Rootworm, D-LdbTot-Loa virgifera, Northern Corn Rootworm, D. longioornis,
Southern Corn Rootworm, D. undea-impunGtata howardi
Adult corn rootworms feeding in large numbers (10+ beetles per ear) will eat
corn silks and may prevent pollination. The adults will oviposit in the field,
and if the field is planted to corn during the next growing season infestations
of western and northern corn rootworm larvae are highly probable.
The stage of the crop at application is the silk stage when silks are visible
and pollen is being shed.
The stage of insect at application is the adult.
Usually only one application is made. When silking intervals are prolonged
or when rainfall may interfer with the first application, a second application may
be necessary.
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Sampling:—Adult counts of at least 10 randomly selected corn plants are made
in the center of each treatment per replication (block). Counts are made prior to
the first application, 24 hours following application, 72 hours following application,
1 week following application, and 2 weeks following application. Sticky traps may
be placed in each treatment per replication (block) to augment or to replace the
individual plant counts.
After the first insect-killing frost, 10 randomly selected soil cores are
removed from each treatment per replication (block) - 5 samples are taken from
within the rows and 5 from the interrow space. A single 1 pint composite sample
is drawn from the thoroughly mixed whole sample originating from the 10 sub samples.
The composite sample is then washed through custom-built rootworm egg extractors
and the sample is counted for number of rootworm eggs. These eggs will hatch
during the next growing season and the counts can be used to estimate insecticide
effectiveness in reducing the infestation during the next growing season.
COTTON
Insect pests are generally present in cotton throughout the cotton producing
areas of the United States in sufficient numbers to seriously effect yields of
cotton unless control measures are applied. Insects of primary importance are
the boll weevil, Anthonomous grand-is Boheman; the bollworm, Heliothis sea (Boddie);
and the tobacco budworm, Heliothis virescens (Fabricious). Other arthropods that
are implicated as serious cotton pests include several species of thrips, the
cotton aphid, Aphis gossypii Glover; the cotton fleahopper, Psallus seriatus
(Rueter); spider mites, Tetranychus spp. These insects cause losses estimated
in excess of $350 million to $400 million annually to cotton.
Boll Weevil
The boll weevil is the most important species of insect that attacks cotton
in the United States and suggested evaluation procedures for this pest are empha-
sized. Many other insect pest species may be sampled and evaluated at the time
data are being collected for this insect species.
Crop and Location of Tests:—Select a good agronomic variety of cotton.
Select good uniform soil for the entire plot area.
Locate tests in four to five geographical areas of the boll weevil infested
states.
Plot Size and Design:—
Ground Application-Plots must be large enough to prevent "spill-over," i.e.,
drift of applied materials to adjacent plots. Plots must be large enough that
data collection will not interfere with normal development and maturity of the
crop. For example, pulling squares from very small plots each week to monitor
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boll weevil infestations would delay maturity of the crop. Delayed maturity
could compound the results of evaluation because late maturity could make the
crop more susceptible to late season pests and weather.
The length of the plots also are important in terms of proper application
of pesticides. Generally, when a spray machine first enters a plot, the speed
of the machine and the boom pressure are slightly less than optimum. Thus, the
rate of application may be higher than the intended rate. It is equally important
also in terms of effective sampling procedures. One example is the potential
effect of excessive square or fruit removal during sampling. In addition, plot
size must be related to the behavior of the insect. For example, the boll weevil
female tends to move down a row rather than across rows during her oviposition
period. Thus, samples collected along a single row will "skew" the infestation
data. Plots should be large enough to collect a random sample across and along
several rows to obtain an accurate sample.
The minimum plot size should be 8 rows x 15.2 m (50 row feet); randomized
block; four replications. Collect all data from the center 4 rows of these plots;
do not collect data from plants within ca. 1.5 m (5 feet) of the ends of the plots.
This provides 4 to 8 rows of buffer between data rows for the respective candidate
compounds.
Aerial Application-For aerial application test plots the length of the rows
are extremely important. Each plot should have at least 3 swath widths per plot
(assuming swath width is at least 12.2 m (40 feet). Collect data from the center
swath; at least three sub-samples may be taken from center swath. This will
provide ca. 24.4 m (80 feet) of buffer data collection areas to prevent the
influence of drift. Do not collect data within 45.7 m to 61 m (150 to 200 ft.)
of the row ends because this area is usually not treated as thoroughly as the
center of the plot.
Application and Equipment:—Standard high clearance on tractor mounted
sprayer equipped with at least two nozzles per row mounted on the spray boom.
One nozzle should be mounted directly over row. Calibrate ground sprayer to
deliver 7.57 to 37.85 liters/ha (2 to 10 gallons of spray per acre). Calibrate
aerial application to deliver 7.57 to 11.35 liters/ha (2 to 3 gallons of spray
per acre).
Sampling:—Insect populations should be monitored at least weekly; counts
should be made just prior to each insecticide application (no more than one day
prior to application).
To monitor boll weevil populations, collect data by the square pulling
method. To do so, collect no less than 25 green (do not collect yellow or flared
squares) squares at random from each replicate. When squares become hard to find
(in late August), take damaged boll counts, but this method is much less accurate
because of multiple egg puncture.
Do not combine egg and feeding punctures. Count only egg punctures. Note
egg punctures. Make notes on adult weevils as to general abundance of young
weevils in white blooms, etc. Attempts to count adults on plants can be very
misleading—it is directly proportional to the aggressiveness and thoroughness of
the individual technician.
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Record weekly damage counts and compute seasonal average infestations.
All statistical analysis should be done on these seasonal averages. Report the
weekly counts also so that the influence of unusually abundant rainfall, etc.
can be studied. Yield data should be collected by mechanical harvester. At
least 1/3 of the plot should be harvested for yield data. Care should be exercised
in noting any excessive skips in the rows harvested. Any such skips should be
measured. Often in test plantings, the frequent activity of insect sampling as
well as inadequate planting procedures (for example, fungicides or effective
systemics for early season pests may have been left out) may result in less than
optimum stands. If skips are the result of phytotoxicity factors associated with
the test material they would not be counted, but this is unlikely to result in
skips (more likely to be consistent throughout the plot). Hand harvesting can be
used, but this provides for greater variation in efficiency because of different
people harvesting. Such variation can greatly influence yield data from small
plots.
Analysis and Reporting of Data:—As mentioned above, data should be collected
only from the center rows to allow a buffer between data rows of adjacent plots.
Also, no data should be taken from the ends of rows. Analyze data by Duncan's
new multiple range test and at the 5 percent level of probability.
The following data should be reported:
Name of Investigator:
Address of Investigator:
Crop:
Soil Type (if applicable)
Experimental Design:
No. of Replicates:
Chemical Tested:
Formulation Tested:
Dosages Tested:
Method of Application:
Time of Application(s):
Other Pesticides Applied:
Varieties:
Soil Moisture:
Plot Size:
Lot No.
Per 100 Gallons:
a. Type of Equipment:
b. Type of Spray:
c. Coverage:
a. Date(s):
b. Stage of Crop:
Per Acre:
Bollworm and Tobacco Budworm
The following test methodology to determine the efficacy of insecticides
to control the bollworm and tobacco budworm on cotton is very similar to the
method previously described under Boll Weevil - Cotton. Only the modifications
of that method are noted below.
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Application and Equipment:—Standard high clearance on tractor mounted
sprayer equipped with at least two nozzles per row mounted on the spray boom.
One nozzle should be mounted directly over row. Calibrate ground sprayer to
deliver 7.57 to 30.28 liters/ha (2 to 8 gals, of spray per acre). Calibrate
aerial application to deliver 7.57 to 11.35 liters/ha (2 to 3 gallons of spray
per acre).
Sampling:—Insect populations should be monitored at least weekly; counts
should be made just prior to each insecticide application (no more than one day
prior to application).
For moniotring Heliothis, collect the following data: (1) egg count;
(2) live larvae in terminals (upper 18 inches of main stem); (3) Heliothis—
damaged squares; and (4) Heliothis damaged bolls.
Heliothis egg counts in small plot research can be misleading because moths
are immobile in plots treated with the most effective material, and egg counts
may be equal to or may surpass counts in the controlled plots. However, a record
of egg counts will allow a more accurate determination of effectiveness of an
ovicide—insecticide. For example, there may be 100 eggs per 100 terminals but
the next week only two larvae may be found on those 100 terminals. This is an
indication of the effectiveness of an insecticide with ovicide properties. Count
eggs only in the terminal portion of the plants. Sample 25 randomly distributed
plants per replicate (within the center of the plot rows).
When sampling for eggs monitor live larvae in the terminals. These larvae
will be invariably small (first to third instar). These counts will indicate
the effectiveness candidate compound against small larvae. Check a minimum of
25 terminals per replicate for these counts. Check for squares for bollworm
feeding damage. Again, a minimum of 25 squares per replicate are checked. This
can be done in conjunction with boll weevil sampling.
In mid to late season, monitor Heliothis damaged bolls. This can be done
by examining all bolls in 3.04 m (10 successive row feet) in each replicate.
Thus a total of 12.2 m (40 row feet) are checked for each material. Count the
total number of bolls present and the number of damaged bolls and convert the
data to a percentage damage level or convert the data to the number of bolls and
number of damaged bolls per acre. Either method is useful; however, the latter
method is best because boll load can be correlated with subsequent harvest yield
data.
Whenever possible collect a representative sample of the Heliothis larvae
infesting the plant. Bring them back to the laboratory and identify them to
species. By doing so, the ratio of the two species can be determined on a
periodic basis. This data is very useful in interpreting the efficacy of the
data. However, the collector must be careful with the sampling technique.
Heliothis zea are more susceptible to organophosphate insecticides. Heliothis
viresoens are more tolerant to organophosphate insecticides. Thus, it is suggested
that these collections be made adjacent non treated control plots.
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Referenoes
Arant, F. S. 1951. Cotton insects and their control with insecticides.
Auburn U. Agria. Exp. Sin. Cira. 106.
. 1955. Cotton insects can cost state's growers $50 million in a single
year. Highlights Agric. Res., Vol. 2, No. 2. Auburn U. Agric. Exp. Stn.
Bradley, J. R. 1975. Personal communication.
Duncan, D. B. 1955. Multiple range and multiple F tests. Biometrics. 11:1-42.
Gilliland, F. S. 1975. Personal communication.
Watson, T. F., and M. C. Sconyers. 1955. Comparison of insecticide application
schedules for control of cotton insects. J. Eoon. Entomol. 48:
Lygus, Lygus spp.
Seasonal applications can start and continue or cease based on numberical
counts of the Lygus spp. population. Generally this is from late May through
late August. The established methods are thorough but very time consuming. De
Vac counts take a lot of hours to count and to identify the many different species
of insects present in the samples.
Crop and Location of Tests:—The variety should be a commercial variety
for the test area, e.g., Acala.
The test site should be well selected to ensure a uniform population which
is more likely to occur when the test site is in close proximity to such crops
as safflower and alfalfa. The cotton should be in good growing condition,
established and maintained under good agriculture practice consistent with the
commercial growing requirements of the crop. Soil type shoud be suitable for the
growth of the crop and as uniform as is possible throughout the test site.
Plot Size and Design:—Use a randomized complete block design.
Use at least 4 replicates per treatment. More replicates are needed where
the population is light. Lygus adults are quite mobile, thus plots must be large
enough to reduce migration between the treatments and also from outside areas.
Ground application plots should be 24-32 rows wide.
should be 6-10 swaths (2 x 12 meters) (6 x 40 feet).
Air application plots
Application and Equipment:—Applications should be made on a scheduled basis,
but only as indicated by population sampling. No buffer rows are used but sampling
is to be made from only the center rows of each treatment replication. Always
include an untreated control, if possible, when crop loss is not a factor. Other-
wise, it should be compared to the accepted standard.
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The application equipment on large plots should be of a commercial type and
the liters per hectare dictated by the size of cotton which can range from 57-227
liters (15-60 gal.) per hectare with nozzle placement such as to provide complete
coverage. Usually the pressure will range between 2-3 kgm/cm2 (25-35 psi).
Sampling:—Evaluate population density by making 50 sweeps per one row in
the center of each treatment. Sample on both ends and in the middle of the single
row on experimental plots. Sweeps should be made twice weekly plus a sweep sample
before and after each chemical treatment. Treat only when twice weekly net sampling
indicates that treatment is due.
Treatments should be made in the "early square" stage when 6-8 Lygus adults
and/or nymphs appear per 50 sweeps.
Treatments should be made in the "early bloom" stage when 10 Lygus adults
and/or nymphs appear per 50 sweeps.
Treatments should be made in the "peak bloom" stage when 15-20 Lygus adults
and/or nymphs appear per 50 sweeps.
All new insecticides should be thoroughly checked and evaluated for any
positive or negative effects on yield and quality. In the advanced stage of
evaluation the cotton should be collected, weighed and graded in accordance with
the acceptable commercial methods.
Any type of and the degree of, phytotoxicity should be reported provided it
can positively be attributed to the test foliar insecticides. Such responses as
stunting, leaf burn and chlorosis are usually the factors to evaluate.
Analysis and Reporting of Data:—The data should be analyzed using analysis
of variance at the 5% level and check mortality, if any, accounted for by using
Abbott's formula.
The following information should be included in reporting test results:
Product name and formulation used, indicating active ingredient.
Crop (variety) treated.
Location of the test.
Type irrigation used (furrow or sprinkler).
Plot size.
Number of replications.
Rate of applications - a.i. per hectare.
Finished spray volume per hectare.
Method of application.
Stage of crop growth.
Treatment dates.
Harvest dates.
How samples were taken.
Number of samples taken.
Percent infestation.
Phytotoxicity.
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Comments regarding unusual test conditions or performance.
Temperature and general weather conditions at time of treatment.
Rainfall or any unusual weather after the treatment.
Include comment on performance as related to commercial acceptability.
Statistical analysis.
Reference
Sagaser, J. N. July 19, 1975. Personal written communications. Velsicol
Chemical Corporation, Commercial Development, 6197 Millbrook Avenue,
Fresno, California. 209/431-1678.
Mites, Tetranijc'hus spp.
There are several different species of the Tetranyahus genus that are a
major problem in cotton. The conditions under which they exist or become a
problem varies somewhat from region to region, but usually it is associated with
weak cotton and under hot, humid, dry climatic conditions.
Crop and Location of Tests:—The cotton variety should be one that is
grown in the test area for commercial purposes. Preferrably choose a variety,
if there is more than one grown in the area, that is known to be highly susceptible
to mites.
Soil suitable for cotton should be selected and preferrably an area where
cotton has been grown previously. The soil type should be uniform and prepared
consistent with good agriculture practice for the crop and area. There are
specific activities that can be carried out in each region to encourage good
mite populations and consultation should be pursued with the local Experiment
Station and Extension authorities.
Plot Size and Design:—Use a randomized complete block design so that the
results can be analyzed, statistically.
Use at least 4 replications per treatment and for ground application, each
plot should be at least 16-24 beds wide (large replicates).
Use large replicates for air application, but replicates width's can be 3-4
swaths wide (36-48 meters) (120-160 feet).
With the replicates as large as have been suggested, buffer rows should not
be necessary.
Sampling:—The fact that, under ideal conditions, mites reproduce rapidly
and populations can reach epidemic levels in a short period of time requires
that observations be made every 2-4 days.
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For ground applications collect 25-50 leaves at random through the center
of each plot and from various levels on the plant, i.e. bottom, middle, top.
The leaves should then be brushed using a McBurnie mite brushing machine. Mites
should then be counted, including all stages; egg, larvae and adult. In the case
of larvae and adults, living and dead should also be recorded. The data can be
presented as average living or dead and number of eggs per leaf.
Economically important levels can occur very rapidly under ideal conditions.
Four-five (4-5) mites per leaf is approaching a critical infestation while 10-12
mites per leaf is critical and requires application.
Sample once weekly starting in June or July, and sample before and after
each application. One or two (1-2) mites per leaf after application represents
good control.
Yields are very ambiguous unless they can be directly related to the test
foliar miticide. Yield data is very valuable, but it must be known that it is
a direct result of the miticide or it is worthless information.
Any type of and the degree of, phytotoxicity should be reported, provided
it can positively be attributed to the test foliar miticides. Such responses as
stunting, leaf burn and chlorosis are usually the factors reported.
Analysis and Reporting of Data:—See Lygus - Cotton.
Eeference
Sagaser, J. N. July 19, 1975. Personal written communications. Velsicol
Chemical Corporation, Commercial Development, 6197 Millbrook, Avenue,
Fresno, California. 209/431-1678.
Pink Bollworm, Pect-inophoTa qossyp-iella
The testing and plot design of tests for Pectinophora gossypiella control
are developed around the nature of the insect pest. The adult pink bollworm moth
deposits the eggs under the calyx of the maturing cotton boll. The egg and hatch-
ing larva are protected here from chemical sprays. Except for a very short period
of a few minutes to a couple of hours - between the hatching of the pink bollworm
egg under the boll calyx and until the larva bores into the inside of the boll -
the larva is not out in the open and susceptible to chemical applications. Chemical
applications and research testing for larval control during this short "exposed
period" of the pink bollworm are mostly unsuccessful or only partly successful.
The best method for pink bollworm control is to control the adult moth. Thus,
research programs are most successfully completed by monitoring and treating for
adult moths.
The population density of the pink bollworm adult is most easily and accurately
monitored by using pheromone traps, using daily moth counts to determine: a) if
the pink bollworm is present in the test area; b) if the population density is in-
creasing or decreasing; and c) the effects of various chemical or biological treat-
ments on the adult moth.
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Tests for pink bollworm control should begin sometime in July, in California
and Arizona, in order to synchronize with the period called "peak boll set".
This period is generally the time when the greatest number of vulnerable bolls are
present, greatest crop injury can occur, and when the greatest population of adult
moths is present. Test treatments showing greatest effectiveness during this
period also automatically have demonstrated that the treatment will be effective
on lesser population densities.
Crop and Location of Tests:—A cotton variety should be selected that is
common to the test area and that is known to be susceptible to the pink bollworm.
The variety should be recorded in the test data forms.
Site selection and the time to make the first application are difficult to
determine. Pink bollworm pheromone traps are excellent and accurate, but are
often not readily available or it is expensive to acquire the traps and pheromone.
Boll cutting will give larval counts and establish that pink bollworm is present,
yet does not indicate if the adult moths are present during the test. Larval
counts prove only that adults were present earlier to deposit the eggs.
Plot Size and Design:—Use 4 replications per treatment and a randomized
complete block design.
For ground applications, plots should be one-tenth of a hectare or larger.
Ground applications should have plots separated by a minimum of 2 buffer rows.
Aerial application plots should be a minimum of 3-5 swaths wide (36-60 m)
(120-200 ft.). Be certain that all sampling of traps and bolls is from the center
of each plot.
Application and Equipment:—Two methods may be used for evaluating treatment
effectiveness on pink bollworm adults: a) "one or two application" testing; or
b) "seasonal application" testing.
"One or two application" testing is sometimes the less accurate of the two
methods. The primary reason is that the test is often completed missing the peak
adult moth density, and/or the control treatments are not held under pressure over
a long enough period to be certain that control would be maintained.
This test is often necessary a) when testing time is limited; b) in early
screening trials; and/or c) when sufficient chemical materials are not available
for seasonal use.
The best way to make the test results most accurate with the "one or two
application" method, is to use pheromone traps prior to the peak boll period. The
first adult moth to appear is a fairly accurate estimation of when to apply the
first treatment. If two applications are desired, the second application is applied
one week following the first application.
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The pheromone trap counts early in the season - just before application,
and following application - will measure the effectiveness of each treatment.
Weekly boll cutting of 100 bolls before, during and after application will indicate
each treatment's effectiveness also.
"Seasonal application" testing for pink bollworm is aimed at controlling
the adult pink bollworm.
Pheromone traps should be placed in the field in adequate numbers and
locations to thoroughly monitor the adult moths. Place the traps and make daily
counts early in the season, before pink bollworms normally appear in the field
(prior to peak boll set). Peak boll set is a 5-7 week period, usually starting
in July, when most boll damage and infestation occurs and when the most vulnerable
bolls are present. Application generally starts just prior and during peak boll
set. This usually coincides with the population count increases in the pheromone
traps and infestations in the bolls.
Boll counts should be made after adult moths appear before and after each
treatment is applied. Boll counts are to be used to monitor populations and the
presence of infestations, not to determine when to apply the treatments.
Treatment applications - Apply the treatments weekly for 5-7 weeks, based on
population pressure of pink bollworm adults as determined by the trap counts.
Make daily pheromone trap counts of adults and weekly boll counts throughout the
entire testing season or period.
Sampling:—There are two methods of evaluation of pink bollworm populations:
1) Pheromone traps and daily adult moth counts from the traps. Pheromone
traps are best for monitoring the adult moth population to determine: a) when
the adult moths' presence starts and ends; b) when peak treatment is needed; and
c) the effect of the test treatments on the adult population.
2) Cutting of 100 bolls weekly. Weekly boll cutting of 100 bolls collected
at random from each treatment indicates if indeed pink bollworm is present in the
test area.
Although delayed, boll cutting tends to give an indication of treatment
effectiveness. Boll cutting for larval counts is not a good indicator of when
to start treatments. Larval presence does not mean continued adult moth presence.
As stated earlier, because the larvae are inside of the bolls, larval treatment is
futile. Adult moth kill is the only effective population control of pink bollworm.
Cotton boll selection - At random, collect 100 of only the firm shiny green
bolls, approximately equal to a quarter or a fifty cent piece in size. These
bolls are generally between 12 and 24 days old. Older or younger bolls are not
used for counts becuase younger bolls are not mature enough for the larvae, and
older, tougher hulled bolls cannot be penetrated by the young larvae just hatched
from the egg. Cut each boll and inspect each section of the boll for larvae damage
Always sample bolls at random and from the center of each plot away from
the plot margins.
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Always include a standard and an untreated check for comparison with the
other treatments.
Analysis and Reporting of Data:—See Lygus - Cotton.
References
Dromgoole, Aubrey. 1975 Personal communication. Velsicol Chemical Corporation,
Rocky, Oklahoma.
Leigh, Tom E. 1975. Personal communication. University of California USDA
Station, Shafter, California.
Sagaser, J. N. July 19, 1975. Personal written communications. Methodology for
Experimental Testing of Western Cotton Pests. Velsicol Chemical Corporation,
Fresno, California.
Shlomo, N., N. Green, and I. Teick. 1973. Trapping pink bollworm moths with
Hexalure: Masking effect of geometrical and positional isomers. J. Boon.
Entomol. 66(6):1349.
Shorey, H. H. 1975. New advances in pink bollworm control. Summ. Pros. Beltwide
Cotton Prod. - Mech. Conf. January 8-9, 1975, New Orleans, Louisiana.
National Cotton Council of America, Box 12285, Memphis, Tennessee.
Tuscano, Nicholas. 1975. Personal communication. University of California
Agricultural Extension Service, Department of Entomology, Riverside, California.
Watson, Theo. 1975. Personal communication. University of Arizona, Tucson,
Arizona.
Young, David F., Jr. 1969. Cotton Insect Control, 1st ed. Onmoor Press,
Birmingham, Alabama.
SORGHUM, Sorghum bicolor L. (Moench)
The following suggested methodology for evaluating pesticides for the control
of foliar invertebrate pests of sorghum is identical in general parameters to the
testing of insecticides for efficacy on corn as described previously in this volume.
The differences occur in the sampling procedures following the specific pest. See
Field Crops - Corn for general parameters.
Greenbug, Schizaphis graminwn (Rondani)
The insect feeds on the leaves and stem. While feeding it injects toxic
saliva which destroys plant tissues. Early symptoms are red patches on some lower
leaves and partly or completely necrotic leaves. Moderate greenbug attack causes
stunting and delayed maturity as well as lowered yields. Severly infested plants
may be killed by greenbug feeding.
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The stage of the crop at application depends upon insect infestation, from
emergence to pre-boot and later.
The stage of insect at application is all life stages whenever population
densities of beneficial insects are insufficient to prevent greenbug outbreaks.
The interval between application varies from 1-3 applications, 3-7 days
apart.
Sampling:—Pretreatment greenbug counts from at least 10 randomly selected
sorghum plants from each treatment per replication (block) should be made.
Two or more post-treatment greenbug counts from at least 10 randomly
selected sorghum plants from each treatment per replication (block) should be
made. Sampling intervals vary from 4 to 15 days. A common sampling scheme is to
make counts at 3, 7, 14, and 21 days after application.
As an alternative to whole plant counts, greenbugs may be counted on 1 leaf
from each of 10 randomly selected sorghum leaves per replication (block). The
same numbered leaf (counting from soil level) should be examined on a given
sampling date.
The number and location leaves killed by greenbugs may be recorded in each
plot 1-2 weeks following peak greenbug infestation.
Yields may be obtained by manually harvesting at least 0.0004 ha (0.001 acre)
from each treatment in each replication (block). Manually harvested sorghum heads
may be threshed, and the seeds cleaned, weighed, and converted to kg/ha (Ibs/acre)
at 12.5% moisture. Mechanical harvesters also may be employed.
The effect of the test insecticides on non-target insects, i.e. beneficial
insects, should be recorded for each insecticide.
References
Gate, J. R., Jr., D. G. Bottrell, and G. L. Teetes. 1973. Management of the
greenbug on grain sorghum. 1. Testing foliar treatments of insecticides
against greenbugs and corn leaf aphids. J. Econ. Entomol. 66:945-951.
Daniels, N. E. 1972. Insecticidal control of greenbugs in grain sorghum.
J. Econ. Entomol. 65:235-240.
Harvey, T. L., and H. L. Hackerott. 1970. Chemical control of a greenbug on
sorghum and infestation effects on yields. J. Econ. Entomol. 63:1536-1539.
Teetes, G. L., and J. W. Johnson. 1973. Damage assessment of the greenbug on
grain sorghum. J. Econ. Entomol. 66:1181-1186.
Ward, C. R., E. W. Huddleston, D. Ashdown, J. C. Owens, and K. L. Polk. 1970.
Greenbug control on grain sorghum and the effects of tested insecticides on
other insects. J. Econ. Entomol. 63:1929-1934.
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Sorghum Midge, ContaT-Lnia sorghicola (Coquillett)
The sorghum midge larvae feed on developing ovaries and grain fails to
mature. Affected spikelets remain tightly closed and, in severe infestations,
whole heads fail to set grain. On dissection, larvae and pupae may be seen in
the spikelets.
The stage of crop at application is when 20% of sorghum heads begin to bloom.
The stage of insect at application is the adult.
The interval between applications is 3-7 days. Usually only 1-2 applications
are made.
Sampling:—Adult midges present at midmorning 2-3 days after application can
be counted on at least 10 sorghum heads for each treatment per replication (block)
as a measure of immigration.
The number of midges emerging from 10-40 sorghum heads for each treatment
per replication (block) is determined by excising heads and holding the heads in
emergence cages.
Mature sorghum heads are collected and the levels of midge infestations are
determined by examination based on midge damage to individual florets. At least
10 mature sorghum heads should be harvested from each treatment per replication
(block).
Yields are likely to be the best method of evaluating insecticide efficacy
against the sorghum midge. Yields may be obtained by machine or manual harvest
of a least 0.0004 ha (0.001 acre) sub plots from each replication (block). Manually
harvested sorghum heads may be threshed, and the seeds cleaned, weighed, and con-
verted to kg/ha (Ibs/acre) at 12.5% moisture.
Beferenoes
Huddleston, E. W., D. Ashdown, B. Maunder, C. R. Ward, G. Wilde, and C. E. Forehand.
1972. Biology and control of the sorghum midge. 1. Chemical and cultural
control studies in West Texas. J. Econ. Entomol. 65:851-855.
Randolph, N. M., M. V. Meisch, and G. L. Teetes. 1971. Effectiveness of certain
insecticides against the sorghum midge based on a new method of determining
infestation. J. Econ. Entomol. 64:87-88.
Stanford, R. L., E. W. Huddleston, and C. R. Ward. 1972. Biology and control
of the sorghum midge. 3. Importance of stage of bloom and effective residual
of selected insecticides. J. Econ. Entomol. 65:796-799.
Ward, C. R., E. W. Huddleston, R. A. Parodi, and G. Ruiz. 1972. Biology and
control of the sorghum midge. 2. Chemical control in Argentina. J. Econ.
Entomol. 65:817-818.
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Banks Grass Mite, Oliqonifchus pratensis (Banks)
Mite damage to the sorghum plant is expressed as discoloration, drying,
and/or premature death of the leaves. An additional problem is the death and
subsequent lodging of mite-infested plants. Additionally, the mites may so
weaken the plant that disease organisms partially overcome the natural resistance
of many plants. The symptomatology is: (1) small, white stipuled spots occur
on the leaf along the midribs; (2) the spots increase in size, especially on the
basal 1/2 of the leaf, followed by red or brown discoloration of the spots; (3)
leaves fold downward along the midrib, especially on the basal 1/2 of the leaf, and
death of all or a portion of the leaf follows; (4) symptoms proceed from leaf to
leaf up the plant, and some leaves may be unaffected. Damage to heads consists of
shriveled seeds and extensive webbing.
The stage of the crop at application is the late-mild to early-soft-dough
stage and later stages of plant growth.
The stage of mite at application is all life stages.
Usually only 1 application is made. Under situations of severe stress a
second application ca. 10 days following the first application may be warranted.
Sampling:—Pre- and post-treatment counts are made by visual selection of 10
of the most heavily infested leaves from each treatment per replication (block).
A single microscopic field of 0.5 -in. diam. is selected in the most densely in-
fested area on the leaf. All life stages (eggs, larvae, early and late-stage
nymphs, and adults) of mites in each microscopic field are counted.
An alternative to counting mites while the mites are on the leaves is to
select the 10 most heavily infested leaves from each treatment as described above.
Then, a strip of cellophane tape is placed across the most-dense colony on the
underside of the selected leaf. The tape is then placed on a 1" X 2" glass
microscope slide. The slide is then inverted and the number of mites per unit
area is determined by viewing a 0.5-inch diam. circle through a calibrated micro-
scope field. (Personal communication, Dr. Jay D. Stone, Kansas State University).
Observations are made on plant lodging by counting lodged plants on at least
0.0004 ha (0.001 acre) from each treatment in each replication (block).
Reference
Ward, C. R., E. W. Huddleston, J. C. Owens, T. M. Hills, L. G. Richardson, and
D. Ashdown. 1972. Control of the Banks grass mite attacking grain sorghum
and corn in West Texas. J. Eoon. Entomol. 65:523-529.
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SOYBEANS
Insect pests are sometimes present in soybeans throughout the soybean
producing areas of the United States in sufficient numbers to seriously affect
yields of soybeans unless control measures are applied. Soybeans are attacked
by insects that feed on the seedlings, foliage and pods. Insects that attack the
seedlings and stems include various species of cutworms, the three-cornered-alfalfa
hopper and the lesser cornstalk borer. The principal forage feeding insects in-
clude the velvetbean caterpillar, Antioavsia gemmatillis; soybean looper,
Pseudoplusia includens; cabbage looper, Tr-ichoplusia ni; beet armyworm, Spodoptera
exigua; the fall armyworm, Spotoptera frugiperda; the green cloverworm, Plathypena
soabra; the bean leaf beetle, Certoma trifureata; and the Mexican bean beetle,
Epilachna varivestis.
Pod feeding insects include the "podworm," Eeliothis zea; and stinkbugs,
Nezara ver"Ldula; and Aeroscternum hilare. The podworm and stinkbugs are perhaps
the most important insects that attack soybeans. The podworm is the "key" insect
pest to soybeans in the south and southeast. This insect attacks beans from pod-
set to pod-maturity. Infestations are usually heavier following treatment for
foliage feeding insects prior to bloom. The podworm usually occurs in damaging
levels from mid August to mid September. The small worm usually starts feeding
on the leaves and blooms then bores through the pods and destroys several beans.
Both the nymphs and adults of stinkbugs suck juices from young soybean pods
causing discoloration to the beans and subsequent reduction in grade.
Podworm, Stinkbugs and Defoliating Insects
Crop and Location of Tests:—Select a good agronomic variety; select good
uniform soil for the entire plot area.
Locate tests in 4 to 5 geographical areas of soybean production.
Plot Size and Design:—
Ground Application - Plots must be large enough to prevent spill-over, i.e.,
drifts of applied candidate compounds to adjacent plots. Plots should be 4 to 8
rows wide and at least 40 to 50 ft. long (border rows are desirable if the test
area is large enough). The plot should be randomized and replicated at least
four times. The rates of materials, i.e., active a.i. per acre, would be variable
with the objective of the test. The finished spray and volume per acre is variable
but generally within the range of 18.9 to 75.6 liters/ha (5 to 20 gals, of spray
mix per acre).
Aerial Application - For aerial application test plots the length of the
rows are important. Each plot should have at least three swath widths per plot
assuming plot width is at least 12.2 m (40 feet). Collect data from the center
swath; this will provide approximately 24.4 m (80 ft.) of buffer data collection
areas to prevent the influence of drift. Do not collect data within 45.7 m (150 ft.)
of the row ends because its area is not usually treated as well as the center plot.
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Application and Equipment:—Standard high clearance on tractor mounted
spray equipped with at least two nozzles per row mounted on a spray boom. One
nozzle should be mounted over the row. A knap sack sprayer may also be used
preferably with compressed C02 and pressure regulator (2.1-4.2 kg/cm^ (30-60 psi)).
The interval between treatment and observation should be from 24 to 48 hours.
The interval between observation should be 5-7 days for the duration of the grow-
ing season. This is necessary to gain information on impact to non-target species
and resurgence of pest species.
The timing of the application for certain insects is extremely important.
For corn earworm (podworm), it is generally necessary to apply before plants
develop a closed canopy. For the southern green stinkbug, economic infestations
usually do not develop before pod-filling stage (4 to 8 weeks after first bloom).
Crop growth stage should always be noted in materials and methods.
Sampling:—Apply materials as foliar sprays at rates postulated to give at
least 80 percent control compared to untreated checks 48 hours posttreatment.
Make insecticide counts on the two middle rows by shaking or beating the foliage
over a ground cloth and recording live insects from the cloth. Sample at least
six of these points within the center two rows of each plot. Three feet of row
at each point is adequate. Record data on the number of live insects per 5.48 m
(18-ft. of row). Calibrate percent control as follows: Percent control equals
100 x divided by the ck, whereas x equals the average number of live larvae 48
hours after insecticidal treatment and ck equals the average no. of live insects
after 48 hours in untreated check. Eighty percent control is generally considered
the minimum level of control. It is usually extremely difficult to get an accurate
count of dead individuals on most species; consequently, counts of live insects
remaining after 48 hours is important. The degree of plant injury and economic
threshold levels in most bean producing areas is one per foot of row for corn ear-
worms and stinkbugs. For all other defoliate feeders it is 33 percent leaf loss
prior to bloom and pod-set and not to exceed 20 percent after pod-set until pod-
maturity.
Yields should be taken especially if tests involve timing of applications
according to economic thresholds. Harvest before beans become dry enough to
shatter. Fifteen to 18 percent moisture is a good time to harvest.
References
Begum, A., and W. G. Eden. 1965. Influence of defoliation on yield and quality
of soybeans. J. Eoon. Entomol. 58:591-2.
Chant, D. A. 1966. Research need for integrated control. Proc. FAO Symp.
Integrated Pest Contr. p. 103-9. Rome, 1965.
Duncan, D. B. 1955. Multiple range and multiple F tests. Biometrics 11:1-42.
Hill, C. C. 1918. Control of the green cloverworm in alfalfa fields. USD A
Farmers Bull. 932. 7 p.
Ledbetter, R. J., and Max H. Bass. 1975. Soybean insect control. Auburn U.
Circ. E-3.
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Pedigo, L. P., J. D. Stone, and R. B. Clemen. 1970. Photometric device for
measuring foliage loss caused by insects. Ann. Entomol. Soo. Amer. 63:815-8.
Sherman, F. 1920. The green cloverworm (Plathypena soabra Fabr.) as a pest of
soybeans. J. Eoon. Entomol. 13:295-303.
Smith, R. H., and M. H. Bass. 1972a. Soybean response to various levels of
podworm damage. J. Eoon. Entomol. 65:193-5.
1972b. Relationship of artificial pod removal to soybean yields.
J. Eoon. Entomol. 65:606-8.
Todd, J. W., and L. W. Morgan. 1972. Effects of hand defoliation on yield and
seed weight of soybeans. J. Eoon. Entomol. 65:567-70.
Turnipseed, S. G. 1972a. Response of soybeans to foliage losses in South Carolina.
J. Eoon. Entomol. 65:224-9.
1972b. Management of insect pests of soybeans. Proo. Tall Timbers Conf.
Eool. Animal Cont. Habitat Manage. 4:189-203.
Mexican Bean Beetle, Epilaohna varivestis, and Bean Leaf Beetle, Cerotoma trifuroata
The following procedure is adequate for field evaluation of foliar insecti-
cides for the Mexican bean beetle, Epilaohna varivestis (larvae and adults), and
the bean leaf beetle, Cerotoma trifuroata (adults).
Crop and Location of Tests:—Choose a variety that is common to this crop on
a commercial basis and for the area in which the field test evaluation is conducted.
The selected test site should be typical for the crop and selected so that
drift of insecticide from neighboring crops is not a hazard or that interference
from any other practice with adjacent areas will not interfere with the results in
the test plot. The soil should be uniform and prepared in a manner acceptable to
the normal method for that crop. Fertilizer and irrigation, if used and/or
necessary, should be used in accordance with good agricultural practice for the
crop. The test site should, if possible, be selected in an area where there has
been a history of Mexican bean beetle and bean leaf beetle infestations.
Plot Size and Design:—Small plots for preliminary evaluations can be two
rows in width and 15 m (50 ft.) in length. Each plot may be considered a single
replicate and four replicates for each insecticide treatment are considered
desirable. It is also suggested that an untreated buffer row be established between
each plot to minimize the effects of drift. 1.5-1.8 m (5-6 ft.) alleyways are
also recommended to separate the blocks. Such a plot setup should be on a ran-
domized complete block design so that the data may be analyzed statistically for
significance.
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Large plots should be set up on the same basis with a randomized complete
block design. The treatment replicates can be 4-6 rows wide and 30 m (100 ft.)
or more long. In the larger plots it is not necessary to leave buffer zones or
to separate blocks.
Air-applied plots should be a minimum of 36 m (50 ft.) wide (3, 12 m swaths)
to prevent drift and to have enough area in the middle of the plots to select a
random representative plant grouping to make the counts. The length of the plots
should be such that the pilot can fly level and safely for at least 180 meters
(600 ft.).
Application and Equipment:—Small plot applications can be applied with CC^
spray equipment. Such equipment is, by design, compact, light and portable.
This equipment is very adaptable and accurate; and since it is light, operator
fatigue can be kept at a minimum. Nozzle selection should be made on the basis
of complete coverage, and usually a fan-type nozzle is adequate when using 95-151
1 (25-40 gals.), usually 132 1 of spray solution per hectare at 3-3.5 kgm/cm2
(25-30 psi). All evaluations, of course, should be done prior to applying the
test materials. Sprayer should be well cleaned before each test and between the
applications of different rates for each treatment. It is advisable to progress
from low to high rate to minimize problems of contamination from one treatment to
the next.
Large plot applications should follow the same basic outline; however, with
much larger plots and with commercial-type spray equipment and all plots should
be set up using a randomized complete block design.
The same plot setup should be used with air application, using 19-38 1 (5-10
gals.) of total spray per hectare. Replication is important, but randomizing
the plots is difficult with air application.
The number of applications will depend on the density of the insect population;
usually a 7-10 day schedule is more than adequate, but should be dictated by the
presence of pests in the test area and that relationship to the untreated controls.
Sampling:—The population level of the insects can be determined by taking
five sweeps per plot with a 38 cm (15 in.) net or by spreading a 1m (3 ft.) long
drop cloth between the rows and dislodging the insects from the plants on both
sides of the cloth by tapping the plants with a stick. The insect counts can then
be recorded as the X number of insects, according to species per sweep or per 1.8 m
(6 ft.) of row 1 m (3 ft.) on each side of drop cloth.
An estimation of insect feeding damage is also made for each plot on a scale
of 0-100%. Each insect's feeding damage is unique and thus easily recognizable.
CeTotoma trifurcata eat rounded holes in the foliage while E. vavivestis skeletonize
the leaves. It should be mentioned, however, that this technique of evaluation
is limited to one application and not multiple sprays, since the feeding damage
evaluation at the time of the first spray could not be distinguished from the feed-
ing damage of the second and subsequent sprays.
See also Introduction - General Methods.
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Eefer-enoe
Tysowsky, Mike, D. H. Brooks, and R. A. Herrett. July 17, 1975. Field test
procedures. Personal communications. ICI United States, Inc., P.O. Box 208,
Goldsboro, North Carolina. 919/736-3030.
Southern Green Stinkbug, Eezar>a viridula (L.)
The southern green stinkbug, Nezara viridula, readily feeds on developing
soybean seed in many areas of the southeastern United States. The nature and
extent of the damage depends upon the state of seed development at which feeding
occurs. Prices paid for soybeans are discounted for stink but damage based on %
of the actual percentage of stinkbug damaged seed. Germinated emergence and
seedling survival are reduced significantly by all degrees of southern green stink-
bug damage.
Crop and Location of Tests:—Test plants should be a variety common to
commercial soybean production, such as "Bragg", and planted in accordance with
the normal planting season for soybeans in the test area. The variety should be
known to be reasonably susceptible to green stinkbug infestations. Other common
varieties grown in the test area are acceptable.
The test site should be so selected to be void of any possible drift hazards
from other fields where insecticides may be applied. The crop should be planted
and maintained in accordance with good agriculture practice for that crop and for
the region in which the test site is located. The lime and fertilizer should be
applied in accordance with soil test recommendations.
Since stinkbug populations will be affected by existing climatic conditions,
care must be taken to see that good records of climatic conditions are maintained
and reported or referenced in all reports.
Application and Equipment:—Use a randomized complete block design. Use at
least 6-8 replicates. In order to maintain a known population, artificial infesta-
tion into cages over soybean plants is recommended.
Small plots can be applied with back pack sprayers with a spray wand prepared
so that the entire plant is sprayed, usually one nozzle over the top and one from
each side. Use 57-95 1 (15-25 gals.) per hectare at 2-2.1 kgm/cm2 (24-30 psi).
For large plots use commercial spray equipment preferrably with drop nozzles
to ensure complete coverage. Use 57-95 1 (15-25 gals.) of spray mixture per hectare
at 2-2.1 kgm/cm2 (25-30 psi). Use .2 to .4 hectare (%-l acre) plots.
For air application use at least 3 swath widths (1x12x36 m) (3x40x120 ft.)
per plot at 19-38 1 (5-10 gals.) per hectare. Plots should be at least .4 hectare
(1 acre) in size so as physical drift will not occur from adjacent plots.
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Sampling:—The value of the foliar sprays may be determined by placing
cages 1.8 x 1.8 x 3.6 m (6 x 6 x 12 ft.) with 1.8 cm (3/4 in.) galvanized iron
pipe frames over 2 rows, 3.6 m (12 ft.) long after the sprays have been applied
and dried on the plants. The stinkbugs are then artificially infested by placing
fourth instar in the cages using 15 bugs per row meter. It is not necessary to
sex the insects. Counts should be made by counting the number of live insects on 3,
7 and 14 days. Before the cages are set over the rows, all insects should be
removed from the area to be caged.
Data should be presented as percent mortality based on number living and
dead. The fourth instar stinkbugs should be collected from an untreated field.
See also Introduction - General Methods.
Eeferenoes
Blickenstaff, C. C., and J. L. Huggass. 1962. Soybean insects and related
arthropods in Missouri. Missouri Agvio. Exp. Stn. Bull. 803, p. 51.
Duncan, R. H., and J. R. Walker. 1968. Some effects of the southern green
stinkbug on soybeans. Louisiana Agrio. 12:10-11.
Johnson, B. J., and M. D. Jillium. 1969. Effect of pesticides on chemical
composition of soybean seed. Agronomy 61:379-380.
Miner, F. D. 1966. Biology and control of stinkbugs on soybeans. Arkansas
Agric. Exp. Stn. Bull. 708, p. 40.
Todd, J. W. , and S. G. Turnipseed. 1974. Effects of southern stinkbug damage
on yield and quality of soybeans. J. Boon. Entomol. 67(3):421-26.
SUGAR BEETS
Beet Armyworm, Spodoptera exigua, and Fall Armyworm, Spodoptera frugiperda
This procedure is adaptable to both small and medium-sized plots for
insecticide evaluation of the beet arymworm, Spodoptera exigua, and the fall
armyworm, Spodoptera frugiperda, on sugar beets.
Crop and Location of Tests;—Choose a variety that is common to this crop
on a commercial basis and for the area in which the field test evaluation is
conducted.
The selected test site should be typical for the crop and selected so that
drift of insecticide from neighboring crops is not a hazard or that interference
from any other practice with adjacent areas will not interfere with the results
in the test plot. The soil should be uniform and prepared in a manner acceptable
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to the normal method for that crop. Fertilizer and irrigation, if used and/or
necessary, should be used in accordance with good agricultural practice for the
crop. The test site should, if possible, be selected in an area where there
has been a hisotry of beet armyworm infestation.
Plot Size and Design:—Small plots for preliminary evaluations can be two
rows in width and 15 m (50 ft.) in length. Each plot may be considered a single
replicate and four replicates for each insecticide treatment are considered
desirable. It is also suggested that an untreated buffer row be established be-
tween each plot to minimize the effects of drift. 1.5-1.8 m (5-6 ft.) alleyways
are also recommended to separate the blocks. Such a plot setup should be on a
randomized complete block design so that the data may be analyzed statistically.
Large plots should be set up on the same basis with a randomized complete
block design. The treatment replicates can be 4-6 rows wide and 30 m (100 ft.)
or more long. In the larger plots it is not necessary to leave buffer zones or
to separate blocks.
Air-applied plots should be a minimum of 36 m (100 ft.) wide (3, 12 m swaths)
(40 ft.) to prevent drift and to have enough area in the middle of the plots to
select a random representative plant grouping to make the counts. The length of
the plots should be such that the pilot can fly level and safely for at least 180 m
(600 ft.).
Application and Equipment:—Small plot applications may be applied with C02
spray equipment. Such equipment is, by design, compact, light and portable. This
equipment is very adaptable and accurate, and since it is light, operator fatigue
can be kept at a minimum. Nozzle selection should be made on the basis of complete
coverage, and usually a fan-type nozzle is adequate when using 95-151 1 (25-30 gals.),
usually 132 1 (30 gals.), of spray solution per hectare at 3-3.5 kgm/cm2 (25-30 psi).
All calculations should be done prior to applying the test materials. Sprayer
should be well cleaned before each test and between the applications of different
rates for each treatment. It is advisable to progress from low to high rate to
minimize problems of contamination from one treatment to the next.
Large plot applications should follow the same basic outline; however, with
the large plots and with commercial-type spray equipment and, all plots should be
set up using a randomized complete block design.
The same plot setup should be used with air application, using 19-38 1 (5-10
gals.) of total spray per hectare. Replication is important, but randomizing the
plots is difficult with air application and is generally not considered necessary.
The number of applications will depend on the density of the insect population;
usually a 7-10 day schedule is more than adequate, but should be dictated by the
presence of pests in the test area and that relationship to the untreated controls.
Sampling:—Pre-treatment insect counts are necessary and it is suggested
that the counts be made on a random basis by choosing 5-10 plants per row, closely
examining for insect damage and recording the number of larvae present. Counts
should be made on plants within the first or last 1.5 m (5 ft.) of each row.
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Post-treatment insect counts on days 1, 7 and 14 after spray application
should be made in the same manner as for the pre-treatment counts. Additional
sprays can be applied to the plots if the insect pressure within them builds to
high levels.
See also Introduction - General Methods.
References
Harris, C. R. , H. J. Svec, S. A. Turnbull, and W. W. Sans. 1975. Laboratory
and field studies on the effectiveness of some insecticides in controlling
the armyworm. J. Econ. Entomol. 68(4):513-516.
Janes, M. J., and G. L. Greene. 1969. Control of fall armyworms and corn earworms
on sweet corn ears in Central and South Florida. J. Econ. Entomol. 62:1031-3.
Moore, S., and D. E. Kuhlman. 1968. Effectiveness of several organic phosphate
insecticides applied as ultra low volume aerial sprays against the true
armyworm on wheat in Gallatin County, 111. Proc. North Central Branch ESA.
23:154-6.
Tysowsky, Mike, D. H. Brooks, and R. A. Herrett. July 17, 1975. Field test
procedures. Personal communications. ICI United States, Inc., P.O. Box 208,
Goldsboro, North Carolina. 919/736-3030.
Weinman, C. J., and G. C. Dicker. 1951. The toxicity of eight organic insecticides
to the armyworm. J. Econ. Entomol. 44:547-52.
SUGAR CANE
Sugarcane borer, D-iatraea saccharalls
This test method is intended for the field evaluation of the efficiency
of insecticides for the control of sugarcane borer, Dlatraea saccharalls.
Granular insecticide formulations have been recommended for the past decade for
the control of this pest. In the most recent years, interest has developed in
the use of low volume and conventional sprays for this purpose. The development
of systemic insecticides effective for control of Lepidopterous borers and recent
advances in aerial application techniques that permit low volume application of
several insecticides have made spray programs feasible.
Crop and Location of Tests:—A variety should be selected that is commer-
cially grown in the area and that is maintained and planted under good agricultural
practice known to be acceptable for the crop in the test area. Scientific name
and variety of crop should be recorded.
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The test site selected should have a previous history of sugarcane borer
infestations. Soil type should be favorable and free of other pests or problems
that may influence the results. The test site should be located so drift from
neighboring crops and/or tests could not occur. The insect population should be
uniform.
Plot Size and Design:—Small plots are 3 rows by 7 m (24 ft.). Treatments
should be replicated 4 times. Treatments should occur in 2-3 week intervals.
At harvest it is suggested that 20 stalks be examined and the number of joints
bored recorded.
In large plots, it is suggested that 25 to 50 randomly selected stalks be
examined for feeding in the leaf sheath and examined for borer larvae. Record
the number of live and dead larvae in post-treatment counts. For pre-treatment
counts, follow the same procedure and correct for check mortality using Abbott's
formula.
Application and Equipment:—It is suggested that the plots be set up on a
randomized complete block design with treatments replicated 4 times. More
replications are required in areas where infestations are slight.
Untreated controls should be used to determine the sugarcane borer population
and to provide a good comparison for the treatments. In addition, a recommended
and accepted standard should be used to compare the acceptance of the experimental
compounds on a commercial basis. If it is impossible to have an untreated control,
then the latter should suffice provided there is an acceptable population of
insects.
The equipment should be well maintained and cleaned well after each treatment.
In the case of liquids, water should be run through the system until it is clear
and the granular equipment should be dusted and preferably some non-toxicant
granules run through the machine to avoid contamination of subsequent treatments.
Always start with the lowest rate to the highest rate. Using this sequence will
minimize the problem of contamination.
When applying sprays as a ground broadcast spray, fan-type nozzles properly
spaced to the nozzle specifications on the boom will provide adequate and thorough
coverage.
Select amount of finished spray per hectare that compares closely with commercial
applications for air and ground applications consistent with the various types of
formulations, i.e. liquid and granular.
Sampling:—Tests should be initiated just prior to or at the time larval feed-
ing begins. Treatments are usually initiated when 5% of the sugarcane stalks are
infested with early instar larvae of the second generation. Applications should
be made on a 2-3 week interval schedule. When feasible and on the basis of the
judgement of the individual investigator, more than one interval should be evaluated.
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For the small plots at a normal harvest, record the number of bored joints.
In the large plot tests, 25-50 randomly selected stalks should be examined for
signs of feeding in the leaf sheath and for borer larvae, recording the number of
live and dead larvae in post treatment counts.
See also Introduction - General Methods.
References
Hensley, S. D., and E. J. Concienne. 1968. Recent developments in insecticidal
control of the sugarcane borer in Louisiana. I.S.S.C.T. Proa. 13th Congress,
Taiwan. Elsevier Publishing Company, Amsterdam.
Hensley, S. D., E. J. Concienne, W. J. McCormick, and L. J. Charpentier. 1967.
Azodrin - a new promising insecticide for control of the sugarcane borer
in Louisiana. Sugar Bull. 45(8):110-114.
Long, W. H., E. J. Concienne, L. D. Newsome, S. D. Hensley, and R. Mathes. 1958.
Recommendations for controlling the sugarcane borer. Sugar Bull. 26(10) : 129-130.
SUNFLOWERS
Sunflower Moth, Homoeosoma eleatellum
Sunflowers are grown under a wide range of conditions in California,
Minnesota, the Dakotas and Texas with an approximate acreage of 500,000-600,000;
however, statistics show quite an acreage variation from year to year. The
acreage has increased over the years and now represents a significant acreage of
a high-cash crop. The sunflower moth, Homoeosoma eleotellum, is considered a
major pest of sunflowers.
Crop and Location of Tests:—The test plants should be a commercial hybrid
of the hybrid sunflower, Heli-anthus annuus L., and one that is commonly grown in
the test area. If possible, select a variety that is known to be susceptible to
the sunflower moth. Planting time is important; a little later planting will in-
crease the insect population but usually decrease quality and yield. However,
this does not apply to the Texas high plains.
The test site should be typical of the area in which the crop is grown com-
mercially. Soil type should be uniform and prepared with a cultural method
consistent with growing the crop commercially. For the test area the crop should
be fertilized and irrigated if necessary, but maintained under good agricultural
practice for the crop in the area the test is located. Attempts should be made
to locate plots in close proximity to shelterbelts, grassed waterways, roadside
ditches, etc., to maximize possible insect infestations. Because of the environment
and insect behavior, a minimum of two locations for each study is suggested.
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Climatic conditions will cause wide variation in the insect populations,
and hence as many locations as possible should be used to provide reliable results.
Plot Size and Design:—The use of statistically designed test plots in
sunflower pest evaluation, in the eyes of the authorities, is one of personal
choice. Some use randomized complete block designs and some use simple plot
techniques designed around the insect population with a given field.
At least four replications should be used per treatment and more replications
may be necessary where the insect population is moderate to light.
Each replicate should have the same number of plants and be the same size
and, in the case of sunflowers, for small plots at least, a minimum of 3 m (10 ft.)
fallow buffer is maintained on all sides of each plot.
For small plots the initial year to two years of study: the plots will depend
on insect population with plots in the area of six rows [100 cm (40 in.)/row] by
16.32 m (54.4 ft.) in length (1/10 of a hectare) (1/40 acre). Plots of this size
are not too large and yet will be adequate if yield information is desired at this
stage of insecticide evaluation.
Large plots: it is again up to the individual researcher, but usually plots
of this nature will run from 0.4-4 ha (1-10 acres) in size. In these plots it is
recommended that buffer areas of at least 7.5 m (25 ft.) be used.
For aerially sprayed plots a minimum of five acres is used and two-three
replicates are suggested. Because of the size of the plot, untreated checks are
not recommended and the use of a recommended standard foliar insecticide is con-
sidered adequate.
Application and Equipment:—Most of the work has been done with six-row
sprayers [100 cm (40 in.)/row] over the top. The procedure and equipment to use
should approximate commercial equipment, and the amount of spray solution and
pressure used should be consistent with that used commercially. Small plots are
at the discretion of the researcher himself, and small equipment well proven as
research equipment will suffice. The research should, when using different rates,
progress from low rates to high rates to minimize contamination when moving from
one rate to another. Sprayers should be thoroughly cleaned after application of
each treatment. Take safety precautions.
Sampling;—Methods used for making control evaluations vary tremendously
from one researcher to the next. There should be 2, 3 or 4 applications usually,
and after the last application a minimum of 100 heads should be cut and taken to
the laboratory for evaluation for insect numbers and damage. Applications should
begin when 20% of the heads are in the flower stage. Some researchers use the
DeVac machine, and when it is used, results should be presented as for other methods.
However, its value in sunflower moth evaluations has not been established.
See also Introduction - General Methods.
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RefeTences
Adams, A. L., and J. C. Gaines . 1950. Sunflower insect control. J. Econ.
Entomol. 43:181-84.
Carlson, E. C. 1967. Control of sunflower moth larvae and their damage to
sunflower seeds. J. Econ. Entcmol. 60:1068-71.
Criswell, T. M. July 29, 1975. Personal communication. Velsicol Chemical
Corporation, Marlin, Texas.
Knowles, P- P., and W. H. Lange. 1954. The sunflower moth. Calif. Agric.
Muma, M. H. 1950. Control tests on sunflower insects in Nebraska. J. Econ.
Entomol. 43:477-80.
Phillips, R. L., N. M. Randolph, and G. L. Teetes. 1973. Seasonal abundance
and nature of damage of insects attacking cultivated sunflowers. Texas
Agric. Exp. Stn. MP-1116. Texas A&M University, College Station, Texas.
Schulz, J. T. July 22, 1975. Personal communication. Department of Entomology,
North Dakota State University, Fargo, North Dakota 58012.
Teetes, George L., M. L. Kenman, and N. M. Randolph. 1971. Differences in
susceptibility of certain sunflower varieties and hybrids to the sunflower
moth. J. Econ. Entomol. 64(5) : 1285-1287 -
Unger, P. W. , A. R. Jones, and R. R. Allen. 1975. Sunflower experiments at
Bushland on the Texas High Plains, 1974. Prog. Rep. Texas Agric. Exp. Stn.
Texas A&M University, College Station, Texas.
TOBACCO
Tobacco Budworm, Eeliothis virescens, Tobacco Hornworm, Manduca sexta, and
Cabbage Looper, Trichoplusia ni
Tobacco is a fairly localized restricted acreage luxury crop which is very
susceptible to attack by several phytophagous insects, the most important of
which include Lepidopterous, Coleopterous and Homopterous species.
It is important to determine the levels of pest populations in commercial
fields and, wherever possible, include a comparison with a standard product.
Although this protocol deals with evaluation methods, it nevertheless should
be pointed out that smoke flavor tests and resulting residues in green and cured
tobacco should be considered very early in the evaluation program.
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Crop and Location of Tests:—The tests should be set up on a variety that
is grown commercially in the area and, preferrably, tests should be set up to
cover different varieties, since each one can react differently to insecticides.
If different varieties are used, however, each variety should be checked individ-
ually and as a separate test. The crop in the selected test site should be planted,
grown and maintained in accordance with the accepted practice for the crop.
Soil that is typical, uniform and suitable for the growth of tobacco should
be selected. The test site should be so selected that it is relatively free of
drift from pesticide treatments of neighboring crops.
Climatic conditions are very important, and optimum conditions such as rainfall,
temperature and soil moisture are all conducive to high insect populations when
good to ideal. Tobacco is very susceptible to climatic conditions, and adverse
conditions can produce plant symptoms which are often confused with insect damage
such as stinkbugs, which are commonly called dry weather sun scald.
Application and Equipment:—Use a randomized complete block design. Use at
least 4 replications per treatment. More replications will be needed if the insect
infestation is light. Each plot should be 2 rows wide by 9.6-12 m long for small
plots and preliminary evaluation, and twice that size for more advanced evaluations.
In the case of budworms, it is usually necessary to make at least two or more
applications at weekly intervals until flower buds appear. Treatments should begin
when budworms of any size are found on 5 or more plants out of 50 any time prior to
flowering.
Hornworms are easily controlled and treatments are justified when 5 or more
hornworms 2.5 cm (1 in.) or longer are found per 50 plants.
The cabbage looper, which is becoming increasingly more important as a tobacco
pest, can occur throughout the development of the tobacco plant since there is
more than one generation per season. Damage is to the leaves as opposed to the
bud for the hornworms and budworms. The larvae is the only damaging stage and eats
ragged holes in the leaves.
Equipment should be cleaned well before each application and treatments should
be made so that the rates progress from the lowest to the highest concentration.
Use one full cone nozzle 30-45 cm (12-18 in.) over the top of each row and apply
a minimum of pressure, i.e. 1-1.4 kgm/cm2 (15-20 psi).
Sampling:—All plants should be checked in both the treated and check plots
and there should be at least one larva per plant to consider that plant infested.
Record infested plants and, on post treated counts, new damage to leaf surface
areas should be checked. Post treatment counts in shade tobacco should be made
every 7 days, and on flue cured tobacco every 14 days.
A high degree of control is necessary, since the insect damage will signifi-
cantly reduce the value of the crop. Control should be at least 90%, although in
many cases a lower percentage is often accepted by the grower, but he is usually
"docked" significantly in the purchase price.
See also Introduction - General Methods.
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Green Peach Aphid, Myzus persioae, and Tobacco Flea Beetle, Epitrix hirtipennis
The green peach aphid, Myzus persicae, is usually a problem throughout the
growing season, but will decrease as the plants become more mature and weather
conditions are not optimum for its development late in the season.
Application and Equipment:—All insecticides should be thoroughly applied
beginning in the early stages of the crop, and test can be continued throughout
the normal growing season. Use up to 57-95 1/ha, less for the small plants and
the maximum amount as the plants approach maturity. Use 2-2.1 kgm/cm^ (25-31 psi)
when making application using a cone nozzle.
Sampling:—For the performance evaluation of the green peach aphid, actual
insect counts per leaf can be made. The counts should be made 4 leaves down from
the bud, selecting a leaf 7.5 cm (20 in.) long or longer. The right half of the
dorsal upper surface between the fourth and fifth lateral veins should be used
and all the aphids in that area should be counted.
Tobacco flea beetle, Epitrix hirtipennis, performance evaluation for early
season should include an evaluation of the number of holes in leaves of the check
plant and all the leaves on at least 10 plants, or examination of enough plants
in the check plot to yield a total of 50 holes recorded. An equal number of plants
in the treated plots should be examined and the number of holes counted and recorded,
See also Introduction - General Methods.
References
Anonymous. 1958. Flue Cured Tobacco; Diseases, Nutrient Deficiencies and Excesses,
Injurious Pests of Cured Tobacco. American Tobacco Company, 245 Park Ave.,
NY 10017.
Anonymous. 1973. Georgia and tobacco. America's Industrial Growth. (Tobacco
History Series, first ed.) The Tobacco Institute, 1776 K Street N.W. ,
Washington, D.C.
Bennett, R. B. , S. N. Hawks, and J. W. Glover. 1964. Curing Tobacco "Flue-Cured".
North Carolina Agric. Ext. Serv., Ext. Circ. No. 444.
Collins, W. R. , S. N. Hawks, Jr., B. 0. Rittrell, R. L. Robertson, F. A. Todd, and
R. Watkins. 1972. Tobacco Information for 1973. North Carolina Agric.
Ext. Serv., Misc. Publ. No. 90.
Kyle, Melvin L. Personal communication. Velsicol Chemical Corporation, Lynnfield
Office Park, 1255 Lynnfield Road, Memphis, Tennessee.
Mistrick, Walter. 1975. Personal communication. Department of Entomology, North
Carolina State University, Raleigh, North Carolina.
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Mistrick, W. J., and F. D. Smith. 1971. Control of tobacco budworm on flue
cured tobacco with insecticides applied mechanically. J. Econ. Entomol.
64:126-32.
Reagan, T. E., R. L. Rabb, and W. K. Collins. 1974. Tobacco budworms: Influence
of early tapping and sucker control practices on infestations in flue cured
tobacco. J. Econ. Entomol. 67(4):551-52.
WHEAT, TvitiQ-um spp.
The following suggested methodology for evaluating pesticides for the control
of foliar invertebrate pests of wheat is identical in general parameters to the
testing of insecticides for efficacy on corn as described previously in this volume
The differences occur in the sampling procedures following the specific pest. See
Field Crops - Corn for general parameters.
Greenbug, Seh'izaph'ls graminum (Rondoni)
The aphids feed on the leaves and stem of the wheat plant and inject a toxic
saliva which causes discoloration and tissue destruction. When conditions are
favorable for greenbug outbreaks the infestation may spread rapidly and the entire
field may be killed.
The stage of the crop at application depends upon insect infestation, from
emergence through heading. The most common crop stage for greenbug attack is the
tillering stage.
The stage of the insect at application is all life stages whenever population
densities of beneficial insects are insufficient to prevent greenbug outbreaks.
The interval between application is 3-7 days and the number of applications
varies from 1-3.
Sampling:—Pre-treatment and post-treatment greenbug counts are made by
counting the total number of all stages of greenbugs present in 0.30 m (1 ft.) of
linear drill row of wheat. At least 5-10 such counts are made for each treatment
per replication (block) at randomly selected counting stations. Usually one pre-
treatment count is made and 3-4 post-treatment counts are made on a schedule of
ca. 1, 3, 7, 14 days. The number of important parasites and predators should be
recorded at each counting station.
Yield data are collected by hand harvesting 0.0004 ha. (0.001 acre) areas
within each treatment per replication (block). The heads are threshed and the
grain weighed and converted to kg/ha (Ibs/acre).
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Referenoes
Daniels, N. E. 1970. Greenbug control with foliar applications in wheat and
grain sorghum, Bushland, 1969. Texas Agric. Exp. Stn. Progr. Rep. 2757:5-7,
Ward, C. R. , J. C. Owens, D. Ashdown, E. W. Huddleston, and W. E. Turner. 1972.
Greenbug control on wheat in 1967-69. J. Econ. Entomol. 65:764-766.
WINTER WHEAT
Pale Western Cutworm, Agrotis ovthogonia
The pale western cutworm, Agrotis orthogonia, is a serious pest of winter
wheat throughout most of the Great Plains of the United States and prairie region
of western Canada, particularly during years of dry weather.
Crop and Location of Tests:—The test plants should be a variety that is
grown commercially in the test area and known to be susceptible to cutworms.
Varieties such as "Lancer" or "Scout" may be used.
For best results select a dryland field where the soil type is uniform. The
crop, winter wheat, should be planted consistent with a cultural method that is
typical for the crop in the test area. It should be so selected that it is free
of drift from pesticide treatments to neighboring crops.
Climatic conditions are very important, as dry spring weather favors cutworm
survival; excessive moisture promotes bacterial and fungus diseases that attack
the larvae and may give complete control. Excessive moisture also drives the larvae
to the soil surface and exposes the cutworm larvae to parasites and predators.
Application and Equipment:—Use a randomized complete block design. Use at
least four replicates approximately .01 ha (1/40 acre). Plots should be larger
if populations are light. For large ground plots where compounds are in the
advanced development stage plots of .4-.8 ha (1-2 acres) are acceptable. Air plots
should be larger, each swath about 12 m (40 ft.) with at least 3 swaths per
treatment.
For small plots, a portable boom backpack sprayer with pressure regulator
and compressed air cylinder may be used in .01 ha (1/40 acre) plots. Use 2 kgm/cm2
(30 psi) and 57 1 per ha (15 gals/acre).
Sampling:—Population densities are determined at various post-treatment
intervals by examining four 0.3 m2 (1 ft.2) samples of soil in each plot to a
depth of 10 cm (4 in.). Soil from each samples is hand-sifted through a screen
and larvae counted. Percent control is determined by population reduction versus
the check.
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At harvest, wheat samples may be obtained for yield data by hand-cutting
four 2.5 m (8 ft.) rows randomly selected from the center of each plot. Samples
can be processed through a stationary thresher, after which the seed is chained,
weighed and yields converted to kg/ha (Ib/acre). All data should be analyzed
statistically by applying the F test and treatment means separated by applying
Duncan's Multiple Range Test at the 5% level.
See also Introduction - General Methods.
References
DePew, L. J. 1970. Further studies on pale western cutworm control in Kansas
1968-69. J. Eoon. Entomol. 63(6):1842-44.
DePew, L. J., and T. L. Harvey. 1957. Toxicity of certain insecticides for
control of pale western cutworm attacking wheat in Kansas. J. Eoon. Entomol.
50(5):640-42.
Jacobson, L. H., and S. McDonald. 1966. Chemical control of the pale western
cutworm infesting wheat in Alberta, -Canada. J. Eoon. Entomol. 59(4):965-67,
Pfadt, R. E. 1956. Control of pale western cutworm in wheat. J. Eoon. Entomol.
49(2):145-47.
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FORAGE CROPS
Forage crops and especially alfalfa support a wide variety of insects
and these include species destructive to forage and other crops, pollinating
insects, species that inhabit the forage because of the lush growth but
have very little effect on the crop, and many predators and parasites of
forages or other neighboring crops. It is suggested that the field evalu-
ation of invertebrate control agents should take this variety of insect
species into consideration. In many cases an evaluation test applied for
one species will yield data on other pest and beneficial species if these
are sampled and counted at the time data are being collected for the major
species being evaluated.
Throughout the suggested practices, we will attempt to recommend
minimums for small plot evaluations. Large scale tests with ground equip-
ment should be applied on minimum 2.02 hectares (5 acre) plots.
Minimum plot size for air application should normally consist of at
least three passes of the plane with samples taken in the middle swath.
Spray volume is important in air application and reference is made to
Wilson and Armbrust (1968).
In all cases, evaluations should be made under ideal application con-
ditions and with equipment that is in good working order and properly cali-
brated to give good coverage of the forage. Sampling of certain life
stages of some pests is difficult and time consuming. Care should be
taken to conduct sampling within the central area of the plot with con-
sideration for edge buffer zones within the plot. In all cases a repli-
cated pretreatment sample should be taken within the test field. It is
not necessary to sample each plot. With species that are widely distribu-
ted, it is generally felt that evaluations should be conducted in major
use areas with 2-3 test sites per area.
Alfalfa Weevil and Egyptian Alfalfa Weevil
Because the alfalfa weevil, Eypera post-tea (Gyllenhal) and the
Egyptian alfalfa weevil,Hypera bTunneipennis (Boheman) are the most im-
portant single insect pest species of alfalfa in the United States, we
will emphasize suggested methods for these two pests.
Crop Variety and Location of Tests:—The alfalfa variety should be
one that is susceptible to damage from the particular insect pest species
under test and should be a variety commonly grown in the geographic area
of the test site. A pure stand of alfalfa would be desirable for testing
but in many geographic areas alfalfa is commonly planted mixed with other
forages such as clovers and grasses. In these cases or those where vol-
untary forages have invaded an originally pure stand, a plant composition
sample of the stand should be taken and each forage type including weeds
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should be reported as a percentage. The test should be located In an area
where the weevil has been economically Important for at least one previous
year.
Experimental Design:—A valid experimental design should be used and
we suggest the randomized complete-block design with a minimum of three
replications per treatment. Plot size will depend on which life stage
is being controlled and for how long. For larval control many researchers
have used a minimum plot size of 3.05 X 6.10 meters (10 X 20 ft.).
Because of adult movements within a field and into a field, data to
determine initial adult control should only be collected up to 24 or 48
hrs after the application. Niemczyk and Flessel (1969) obtained satis-
factory results with 0.04 hectare (1/10 acre) plots. To determine the
effectiveness of adult control programs over an extended period of time,
Wilson and Armbrust (1970) and Niemczyk and Flessel (1969, 1970) used
entire fields or a plot size of several acres with the remainder of the
field being treated with a recommended adulticide.
Application and Equipment:—Spray applications rather than granular
applications appear to give better coverage of the chemical unless a low
percentage granular formulation is used. Most researchers feel that a
minimum of 7.57 decaliters per acre (20 gallons) of finished spray should
be used on first-crop alfalfa at 13.8 Newton's per meter2 (20 p.s.i.).
For spraying regrowth after harvest, 3.79 decaliters per 0.4 hectare
(10 gallons per acre) is usually sufficient.
Sampling:—Population densities of each stage of the weevil are very
time consuming to obtain and usually not necessary for comparing one
treatment with another on a relative basis.
For most relative larval sampling the standard 3.8-decimeter (15-
inch) diameter sweep net is used. It is swung across the top of the al-
falfa the way in which the pendulum of a clock swings, One sweep is equal
to one pass of the net and the return is counted as the second sweep
(Armbrust et al. 1969). The number of sweeps should be adjusted to the
population levels so numbers of insects obtained are valid for statistical
analysis. Results should be reported on the basis of mean number of in-
sects collected per sweep.
Adult sampling is difficult because at certain times and under some
conditions, it is difficult to obtain meaningful numbers. We suggest
that the number of sweeps per plot be adjusted so that valid counts of
adults are obtained.
Additional sampling methods, comparison of methods, and processing of
samples are reported by Callahan et al. (1966), Cothran and Summers (1972),
Pass and Van Meter (1966) and Stevens and Steinhauer (1973).
When researchers (Armbrust et al. 1969) are evaluating the performance
of insecticide treatments applied as larval sprays, counts are usually
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made at pretreatment and at 3, 14, and 21 days after application. Where
more precise performance data are needed, additional sampling at 7, 10,
12 and 16 days after application is suggested. An estimate of percent
of the foliage missing at each sampling data is further suggested.
Alfalfa yields in small plots are sometimes difficult to obtain
because of plant variation and density within a stand of alfalfa and be-
cause of the presence of weeds. Hintz (1974) and Koehler and Rosenthal
(1975) have obtained satisfactory results and their methods are suggested.
A high percentage of feed nutrients in alfalfa are contained in the leaves
which weigh very little in comparison to the bulky stems which contain
a large amount of fibrous material of low nutrient value. Thus alfalfa
weight records alone can be very misleading as an indicator of market
value. Chemical analysis for protein is a good indicator of feed value
and should be combined with weight records to assess pest damage. Pro-
tein can be determined by the method given in the 10th edition, 1965
Official Methods of Analysis, page 16, 2.044,
Analysis and Reporting of Data:—Data means should be compared using
a valid statistical test for significance such as Duncan's new multiple-
range test or Tukey's w-procedure. Treatment performance should be com-
pared with untreated forage and one or more standard labeled insecticides
that are recommended for the particular geographic test location.
The following data should be reported:
Insect population counts recorded as number of insects per sweep.
Insecticide formulation used and amount of active toxicant per hectare.
Amount of spray per hectare and the type of equipment.
Plant height and percent of foliage missing at time of treatment
and on each sampling date.
Phytotoxicity rating.
Temperature and general weather conditions at time of treatment.
Rain measurement within 48 hours following treatment.
References
Armbrust, E. J. , H. D. Niemczyk, B. C. Pass, and M. C. Wilson. 1969.
Standardized procedures adopted for cooperative Ohio Valley states
alfalfa weevil research. J. Eoon. Entomol. 62(1):250-251.
Callahan, R. A., F. R. Holbrook, and F. R. Shaw, 1966. A comparison of
sweeping and vacuum collecting certain insects affecting forage
crops. J. Econ. Entomol. 59(2):478-479 .
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Cothran, W. R., and C. G. Summers. 1972. Sampling for the Egyptian
alfalfa weevil: A comment on the sweep-net method. J. Econ.
Entomol. 65(3):689-691.
Hintz, T. R. 1974. The impact of the alfalfa weevil on the alfalfa
crop. Proc. N. Central Br. ESA 29:167-168.
Koehler, C. S., and S. S. Rosenthal. 1975. Economic injury levels
of the Egyptian alfalfa weevil or the alfalfa weevil. J. Econ.
Entomol. 68(1):71-75.
Niemczyk, H. D., and J. K. Flessel. 1969. Development and testing
of a preventive program for control of the alfalfa weevil in
Ohio. J. Econ. Entomol. 62(5):1197-1202.
Niemczyk, H. D., and J. K. Flessel. 1970. Further testing of in-
secticides for a preventive program for control of alfalfa weevil.
J. Econ. Entomol. 63:1330-1332.
Pass, B. C., and C. L. Van Meter. 1966. A method for extracting eggs
of the alfalfa weevil from stems df alfalfa. J. Econ. Entomol.
58(5):1294.
Stevens, L. M., and A. L. Steinhauer. 1973. Evaluating the D-Vac as
a sampling tool for the alfalfa weevil adult. J. Econ. Entomol.
66:1328-1329.
Wilson, M. C., and E. J. Armbrust. 1968. Chemical control of the
alfalfa weevil in Illinois and Indiana. II. The importance of
spray volume in aerial application. J. Econ. Entomol. 61(5) :
1201-1203.
Wilson, M. C., and E. J. Armbrust. 1970. Approach to integrated
control of the alfalfa weevil. J. Econ. Entomol. 63:554-557.
Weevil Parasites
Most weevil parasites are parasitic in the larval stage. Of these,
Bathyplectes curcul-ionis (Thomson) is more wide-spread than any others
and occurs wherever HypeTa postica is found. Many other parasite species
have been listed by Brunson and Coles(1968).
Because peak parasite activity may not always occur at the time of
insecticide applications for weevil control, separate tests may be neces-
sary to determine effects on parasites. Field data are extremely diffi-
cult to obtain because of adult parasite movements between treated plots
and from untreated areas. Spray applications should be applied during
adult activity and net counts made at 24 and 48 hrs after application.
Counts made after 48 hrs would reflect emergence of untreated adult para-
sites and movements of adults into the treated alfalfa from untreated
areas or other plots.
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Researchers are suggested to refer to Davis (1970) for further details
of insecticide control of weevils with resulting effects on parasites.
Care should be taken not to use percent parasitism differences between
treatments as an indication that one insecticide over another is less
detrimental to the parasite. These differences, besides reflecting initial
parasite kill, may also result from different parasite-host ratios during
the post-treatment period.
References
Brunson, M. H., and L. W. Coles. 1968. The introduction, release, and
recovery of parasites of the alfalfa weevil in eastern United
States. Prod. Res. Rep. No. 101. 3-12.
Davis, D. W. 1970. Insecticidal control of the alfalfa weevil in
northern Utah and some resulting effects on the weevil parasite
Bathypleotes curculionis. J. Boon. Entomol. 63:119-125.
Spittlebugs
Crop and Test Site:—Spittlebugs are commonly found on alfalfa, red
clover and birdsfoot trefoil. Spittlebugs have been abundant in the
Eastern and North Central States. These insects produce little masses
of white froth around themselves and the stems of alfalfa, clover, and
other plants from which they suck sap through their sharp beaks. The young
bugs begin feeding very early in the growing season and cause surprising
losses in yield (USDA 1952). Control of the nymphal stage is easier to
evaluate than control of the adults. The latter move readily until egg
laying takes place and evaluation of adult control would require large
plots.
The plots for evaluation of control of the nymphs can be as small as
6.1 x 6.1 meters (20 x 20 feet). The randomized complete-block design
with 4-6 replications per treatment is suggested.
Applications and Equipment:—Spray applications are usually made at
the first sign of spittle. This will appear as a single, small teardrop.
Applications are best made with a low pressure type sprayer with 3.79 to
7.57 decaliters (10 to 20 gallons) of spray per 0.4 hectare (acre).
Sampling:—Counts should be made before the new adults appear. We
recommend counts at pretreatment and 3, 7, 16 days after application.
Counts should reflect the number of spittlebugs/meter2.
Analysis and Reporting of Data:—Same as for weevil except insect
counts reported on a meter2 or ft2 basis.
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Potato Leafhopper
Crop Variety and Locaticm of Tegts;^-The potato leafhopper does much
damage to alfalfa. It is a pale-green, soft-bodied, wedge-shaped winged
insect only about one-eighth inch long when full-grown. It often becomes
extremely abundant on these crops and sucks the sap out of the leaves,
causing them to turn reddish yellow and die (USDA 1952).
Evaluate on alfalfa, red clover, ladino clover, or birdsfoot trefoil.
Experimental Design;—Adult hoppers move rapidly so sizeable plots
are necessary. Some researchers have found that minimum size plots of
6.10 x 12.2 meters(20 x 40 feet) are adequate with 4-6 replications per
treatment.
Application and Equipment:—Apply the spray when populations of
nymphs reach 1-2 per 20 sweeps and use a low pressure type sprayer.
Sampling:—Count only nymphs from sweeps taken in plots.
Analysis and Reporting of Data:—Same as above.
Aphids
Use same test procedure as for potato leafhoppers.
European Chafer, White Grubs, Clover Root Borer and Sitona Species
Crop Variety and Test Site:—Evaluate insecticides for these soil
insects on susceptible crops and varieties.
Experimental Design:—Because the immature stages move very little the
plots can be relatively small (3.05 x 3.05 meters) (10 x 10 feet). Research-
ers have found that randomized complete blocks or Latin Square designs are
adequate with 4 replications per treatment.
Application and Equipment:—Use low pressure type sprayer or granular
applicators.
Sampling:—Usually 3-5 square foot samples taken per plot to depth of
1 foot in the fall are satisfactory for the European Chafer. Where white
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grubs are heavy in permanent pasture, they can be counted on a square
foot or meter basis after pealing back the pod. For the clover root
borer, 10 roots per treatment is usually a satisfactory sample. These
should be washed, dissected for borers and the root injury scored on a
scale of 1-4.
Analysis and Reporting _q_f__Data:--Same as above.
Seed Chalcids and Plant Bugs
Crop Variety and Test Site:—Same as above.
Experimental Design:--Small plots of 6.1 x 6,1 meters (20 x 20 feet)
are satisfactory for seed chalcids but larger plots of 12.2 x 12.2 meters
(40 x 40 feet) are needed for plant bugs.
Application and Equipment:--Same as above.
Sampling:—For seed chalcids, harvest seed pods at random from 3-5
sites per plot. Counts are made by splitting the pods to determine shriveled
vs. plump seeds. Seeds should be held until chalcids emerge.
For plant bugs count only the nymphs sampled with a sweep net.
Analysis and Reporting of Data:—Same as above.
Reference
U. S. Dept. of Agriculture. 1952. Insects Yearbook of Agriculture. 780 p.
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PANGELAND
The low value of rangeland forage, the rough terrain, and the vast
acreages involved usually necessitates -aerial application of insecticides
in almost all instances. Many of the species of insects which damage range-
land forage are quite mobile and this vagility, plus the variability in
population densities and the necessity of evaluating aerial application,
has led to the use of large (20 to 259 ha) plots for efficacy testing.
Plot size often must be reduced in mountain or forest rangeland.
Careful attention should be given to the overall efficacy evaluation
program to insure that the tests in different areas are a part of the same
experimental design so that the number of replicates at a given site can
be reduced. Sub-plots are often selected at random within the large plots
to improve efficiency. Care should be given to selecting plot locations
which will not involve spray applications over ponds or water courses un-
less it is the intention of the researcher to monitor for pesticides in
those areas.
Insecticides in the development stage where crop destruction is required
present a unique problem. In large pastures, electric fences and/or burn-
ing, where practical, may be required. Where possible, rapid determination
of pesticide residue levels can be used to determine whether the crop can
be utilized or if it must be destroyed.
Minimum plot size for aerial application will usually be three swaths
wide by long enough to assume sustained level flight of the aircraft. Plots
must be long enough to allow for variation in initiation of spray at each
end. Plot size may be reduced by the use of smaller, slower aircraft.
Width of plots or separation between plots must be adequate to prevent
drift onto adjacent plots. Preliminary "screening" can be accomplished
by low pressure-low volume sprayers. Minimum plot size is dictated by the
mobility of the insect species involved. Border treatment with pesticides
labeled for the particular use can be used to further reduce plot size.
Insecticides should be applied with carefully calibrated equipment
under acceptable weather conditions. To make certain of this, more than
one day may be required for aerial application of several treatments.
Grasshoppers
Crop Variety and Location of Tests:—Species composition of the vege-
tation and the terrain are usually dictated by the location of economic
infestations of the pest. Care should be given to uniformity of vegetation
and terrain among treatments. Proximity to watering sites will affect for-
age utilization and distribution of livestock.
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Experimental Design:—At least two replicates, with several sub-plots
per replicate should be the minimum. The use of only one plot per treat-
ment may be acceptable when circumstances dictate and prior approval has
been given by the Environmental Protection Agency. Whether or not untreated
control plots are used, the incorporation of a recommended standard insecti-
cide treatment is suggested.
Plots as small as 1.62 hectares (4 acres) or 35.3 x 457.7 meters
(116 x 1502 ft.), separated from each other by similar size strips have been
used for aerial application for grasshopper control in alfalfa, however,
problems of migration of grasshoppers from untreated adjacent rangeland have
been encountered (Jones and Kantack 1973). The same authors used 3.64 hectare
(9 acre) plots which were 91.4 x 396.1 meters (300 x 1300 ft.) adjoining, each
other to reduce this effect. Skoog et al. (1965) used 16.2 hectare (40 acre)
plots (H x V( mile) with the Piper Pawnee, 64.8 hectare (160 acre) plots (^ mile
x % mile) with a Stearman and 518.4 hectare (1280 acre) plots (2x1 mile)
with a TBM. In another study, 32.4 hectare (80 acre) plots (k x ^ mile)
were used with flight heights of 15.2 and 30.4 meters (50 and 100 ft.); 129.6
hectare (320 acre) plots (% x 1 mile) were used with flight heights of 60.8
meters (200 ft.) (Skoog and Cowan 1968). Holmes et al. (1965), in Canada, used
1.2 hectare (3 acre) plots (100 x 145 yds) for ground application with a low
pressure-low volume sprayer equipped with nozzles 50.8 cm (20 in.) apart on
a 9.14 meter (30 ft.) boom with the sprayer calibrated to deliver 37.4 liters/
hectare (4 gal./acre).
Application and Equipment:—Aerial application equipment designed and
evaluated for the aircraft being used should be properly calibrated. Air-
craft designation; boom size and length; number, size of nozzle, or atomizers
and position on aircraft; pressure; aircraft speed; height and swath width;
type of solvent; concentration of solution and quantity of solution used
should be reported. Dye cards for evaluation of deposit uniformity are re-
commended. Flight runs made crosswind usually increase the uniformity of
deposits. Applications should be made under conditions that avoid exces-
sive convection currents.
Sampling:—Population densities of grasshoppers are usually evaluated
with the visualized square foot technique with (Skoog et al. 1965) or with-
out (Jones and Kantack 1973) teasing. Other workers have used the square
yard as a sampling unit. The number of square feet sampled varies from 25
in 1.62 hectare (4 acre) plots to 100 in larger plots. Samples are taken
along transects that divide the plot into thirds (Skoog et al. 1968) or
through the center section and at diagonals to the line of flight (Jones
and Kantack 1973). The edge effect produced by migration from untreated
areas may be especially pronounced in grasshopper studies.
Sampling at approximately the same time of day and under similar
weather conditions can be used to reduce variation (Jones and Kantack 1973).
Jones and Kantack (1973), citing Anderson (1961), state that areas
sampled should be disturbed as little as possible to minimize changes in grass-
hopper distribution and activity.
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Holmes et al. (1965) used a standard 3.8-decimeter (15 inch) sweep net
with three sweepers each taking 30 sweeps in a 1.2 hectare (3 acre) plot.
Grasshopper counts should be taken immediately prior to the treatment
three days and seven days after treatment. Additional information may be
gained by sampling one or two days after treatment.
Analysis _and_^eporjting_ of Data:—Where possible, treatment means should
be compared using a valid statistical test for significance. The standard
material used in private-state-federal control programs in the geographic
area should be included. Replicated untreated plots are also recommended.
The following data should be reported:
Description of terrain, and dominant vegetation, including plant
height, stage and condition at time of treatment.
Insecticide formulation used, kilograms active toxicant/hectare and
liters/hectare of spray.
Describe equipment in detail (type of aircraft or application equip-
ment, speed, height, swath width, type, number and arrangement of nozzles
or other apparatus, etc.
Ground surface temperature, air temperature at 1.22 meters (4 ft.),
wind velocity, and general weather conditions including rainfall amounts
and interval after treatment.
Grasshopper populations, including dominant species and life cycle
stages, immediately prior to treatment, three and seven days after
treatment.
Plant response, phytotoxicity and other observations.
References
Anderson, N. L. 1961. Seasonal losses in rangeland vegetation due to
grasshoppers. J. Econ. Entomol. 54:369-78.
Crowell, H. H. 1975. Professor of Entomology, Department of Entomology,
Oregon State University. Personal communication.
Holmes, N. D., D. S. Smith, S. McDonald, G. E. Swailes, and L. K. Peterson.
1965. Evaluation of three alternative insecticides for control of
grasshoppers in Alberta. J. Econ. Entomol-. 58:77-79.
Jones, P- A. 1975. Technical Director, Agricultural Chemical Division,
FMC of Canada Ltd. Personal communication.
Jones, P. A. and B. H. Kantack. 1973. Grasshopper control tests in South
Dakota, 1966-1967. J. Econ. Entomol. 66:987-988.
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Nielson, G. L. 1975. Chief, Division of Plant Industries, New Mexico
Department of Agriculture. Personal communication.
Skoog, F. E., F. T. Cowan, and K.Messinger. 1965. Ultra-low-volume
aerial spraying of dieldrin and malathion for rangeland grasshopper
control. J. Econ. Entomol, 58:559-651.
Skoog, F. E., and F. T. Cowan, 1968. Flight height, droplet size and
moisture influence on grasshopper control achieved with malathion
applied aerially at ULV. J. Econ. Entomol. 61:1000-3.
Range Caterpillar
The range caterpillar, Hemileuca oliwiae Cockerell, feeds primarily
on range grasses in areas in northeastern and south central New Mexico
at elevations between 1734 and 2438 meters (4,700 and 8,000 feet). The
infestation has extended into southeastern Colorado and the western edge
of the Texas Panhandle. Range caterpillars consume large amounts of foli-
age, waste additional unconsumed parts of leaves and cause other foliage
to be ungrazed because of the presence of irritating spines on the active
larvae and cast skins (Hewitt et al. 1974). Heavy populations may de-
stroy all grass down to the crown, producing conditions conducive to wind
and water erosion.
Crop and Location of Tests:—Species composition of the vegetation
and the terrain are usually dictated by the location of economic infesta-
tions of the pest. Care should be given to uniformity of vegetation and
terrain among treatments. Proximity to watering sites will affect forage
utilization and distribution of livestock.
Experimental Design:—Since migration is limited in the early instars,
plot size can be considerably smaller than is required when the cater-
pillars are large. Migration by large caterpillars is increased as the
density of the population and percentage of standing crop foliage consumed
increases.
For small worms, plots should be at least three swaths wide by 402.2
meters (k mile) in length. For larger worms, the plot width should be at
least doubled. To reduce drift, plots should be separated by an adequate
distance which will depend on wind velocity and direction.
Plots as small as 2.43 hectares (6 acres) have been used for efficacy
tests by airplane against first and second instars.
Watts et al. (unpublished data) has experimented with circular arenas
encompassing approximately 4.18 m2 (5 yd2) to confine known numbers of
small caterpillars within the test plots on an experimental basis to re-
duce variation in density. These arenas were made of six inch strips of
tin forced ca 2.54 cm (1 in.) into the soil. Larger plots, from 20.25 to
259.2 hectares (50 to 640 acres) have been used on other studies in New
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Mexico. Coppeck (unpublished data) conducted preliminary screening tests
with a compressed air hand sprayer on small plots.
Application and Equipment:—Aerial application equipment that is de-
signed for the aircraft being used should be properly calibrated. Aircraft
designation; boom size and length; number, size of nozzle, or atomizers and
position on aircraft; pressure; aircraft speed; altitude and swath width;
type of solvent; concentration of solution and quantity of solution used
should be reported. Dye cards for evaluation of deposit uniformity are
recommended. Flight runs made crosswind usually increase the uniformity
of deposits. Applications should be made under conditions that avoid ex-
cessive convection currents.
Sampling:—Population densities are usually evaluated by counting the
number of caterpillars in square yard sampling areas located well within
the plot. Various sampling schemes, designed to remove bias and assure
coverage of an adequate area, have been used. The sampling scheme used
should assure that an entire swath width and preferably more be included
in the area to be sampled. A minimum of 10.84 m^ (1-yd^) samples or more,
until at least 50 worms are counted, is needed per plot. Additional sam-
ples will increase precision. When 5, 4.18 m2 (5 yd^) arenas are used,
100 caterpillars per arena should be used.
Because of the habits of the range caterpillar, the accuracy of
visual counts is increased by delaying initiation of counting until mid-
morning when ground temperatures have increased enough to initiate activity
in the caterpillars.
Counts should be taken immediately prior to treatment and at intervals
estimated to embrace partial and maximum kill.
Analysis and Reporting of Data:—Where possible, treatment means
should be compared using a valid statistical test for significance. The
standard material used in private-state-federal control programs in the geo-
graphic area should be included. Replicated untreated plots are also re-
commended .
The following data should be reported:
Description of terrain and dominant vegetation, including plant
height, stage and condition at time of treatment.
Insecticide formulation used, kilograms active toxicant/hectare and
liters/hectare of spray.
Describe equipment in detail (type of aircraft or application equip-
ment, speed, height, swath width, type, number and arrangement of nozzles
or other apparatus, etc.).
Ground surface temperature, air temperature at 1.62 m (4 ft.), wind
velocity and general weather conditions including rainfall amounts and
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interval after treatment.
Range caterpillar populations, including composition by instars, immediate-
ly prior to treatment and at intervals to measure partial and maximum population
reduction.
Plant response, phytotoxicity and other observations.
References
Hewitt, G. B., E. W. Huddleston, Robert J. Lavigne, D. N. Veckert, and
J. G. Watts. 1974. Rangeland Entomology. Range Soi. Ser. 2,
127 pp.
Watts, J. G. 1975. Professor of Entomology, Department of Botany and
Entomology, New Mexico State University. Personal communication.
Harvester Ants
Harvester ants of the genus Pogonomyrmex denude areas around their
nests. When colonies are vigorous and numerous, control efforts may be
initiated.
Crop Variety and Location of Tests:—Areas chosen should be repre-
sentative of the region for which control recommendations are needed.
Accurate ant species determination is necessary because of the variation
in the habits of harvester ants. Lavigne (1966), in southeast Wyoming
found that equally effective control, at least with mirex could be ob-
tained by treating any time between the end of May and the end of August,
which is during the season when ants are actively foraging. Knowlton
(personal communication) feels that more effective control is obtained
by treating in the spring in Utah. Lavigne (personal communication) re-
commends that baits be applied in the morning since harvester ants are
often inactive during midday. He further states that baits applied in the
evening are subject to small mammal feeding, especially ground squirrel.
Experimental Design:—Preliminary screening has most often been ac-
complished by individual mound treatment with baits, dusts or EC formula-
tion mixed with water. Because of the variation in colony vigor, size
and foraging, large numbers of replicates are needed. Untreated control
nests should be located at an adequate distance to prevent foraging from
a treated area. Complete overlap in foraging between adjacent nests has
been shown to occur when Pogonomyrmex owy'heei- mound density was high
(Willard and Crowell 1965).
Race (1966) used 40.5 hectare (100 acre) plots separated by untreated
buffer zones of 152.4 meters (500 ft.) for aerial application of baits.
Plots of 40.5 hectares (100 acres) have also been used by Lavigne
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-55-
(unpublished data). Smaller plots could obviously be used for aerial ap-
plication of baits or sprays.
Replicated, untreated check plots should be included in the experi-
mental design.
Application Equipment;—Simple measuring devices are used for indi-
vidual mound treatment. For larger plots, hand spreading or an electric
powered cyclone seeder mounted on a vehicle have been used (Crowell 1963).
Bait dispersal by aircraft requires equipment designed, evaluated and
calibrated for the type of aircraft used. Race (1965) treated large plots
with a Stearman 650 HP aircraft equipped with a "Swathmaster" to spread
the bait. Lavigne (unpublished data) used a Super Cub (PA-18A) equipped
with a similar metered spreader made by Avery Aviation, Inc.
Sampling:—Control evaluations should be made in the spring of the
year following application. Lavigne (1966) excavated every mound in indi-
vidually treated mound tests. Race (1965) excavated 50 mounds in each
40.5 hectare (100 acre) plot and used an index of control to improve pre-
cision in evaluation of efficacy. Lavigne (unpublished data) excavated
100 mounds in the same size plots. He also evaluated the degree of rein-
festation. Mound abandonment with or without subsequent invasion of treat-
ed mounds is possible (Crowell 1963, Lavigne 1966). Another factor to be
considered is that there is a single queen in harvester ant colonies and
no queen replacement is apparently possible.
Analysis and Reporting of Data:—Treatment means should be compared
using a valid statistical test for significance.
The following data should be reported:
Insecticide formulation; diluent and dilution, and amount of active
toxicant and total mix per nest or hectare.
For baits, include name of bait, source and composition.
Plot size, layout, mound density and size or vigor, and species of
harvester ant involved.
Percent control on the basis of dead colonies or an index by degree
of control.
References
Crowell, H. H. 1963. Control of the western harvester ant,, Pogonomyrmex
occidental-is with poisoned baits. J. Econ. Entomol. 56:295-8.
Knowlton, G. F. 1975. Professor of Entomology, Emeritus, Department of
Biology, Utah State University. Personal communication.
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Lavigne, R. J. 1966. Individual mound treatments for control of the
western harvester ant, Pogonomyrmex occidentalis in Wyoming. J,
Econ. Entomol. 59:525-32.
Lavigne, R. J, 1975. Professor of Entomology, Entomology Section,
Division of Plant Sciences, University of Wyoming. Personal com-
munication.
Lavigne, R. J., and H. G. Fisser. 1966. Controlling Western Harvester
Ants. Mountain States Regional Publication 3, 4 p.
Race, S. R. 1964. Individual colony control of the western harvester
ant, Pogonomyrmex occidentalis. J. Econ. Entomol. 57:860-4.
Willard, J. R,, and H. H. Crowell. 1965. Biological activities of the
harvester ant, Pogonomyrmex owyheei in central Oregon. J. Econ.
Entomol. 58:484-89.
Imported Fire Ant
Crop Variety and Location of Tests:—Experiments should be conducted
on heavily infested areas typical of the area for which control recommenda-
tions are to be made.
Experimental Design:—At least two replicates with several subplots
per replicate are desirable. Untreated and/or a standard insecticide
treatment should be used.
Minimum plot size for ground application is determined by migration
from untreated areas, crossfeeding, or from plots where poor control is ob-
tained. Markin and Hill (1971) used .405 hectare (one acre) plots isolated
with 15.2 meter (50 ft.) wide chemically treated borders to prevent migra-
tion; however, this did not prevent new queens from flying into the area
after treatment and establishing new colonies. Lofgren et al. (1963) and
in personal communication recommended 2.43 to 3.24 hectare (6 to 8 acre)
plots with 3, .405 hectare (one acre) sampling subplots within the large
plots. For aerial plots, Markin and Hill (1971) used 8.1 hectare (20
acre) plots with 10 randomly chosen .08 hectare (1/5 acre) circular sub-
plots for counting.
Application and Equipment:—Hand operated Cyclone seeders, power-take-
off model Cyclone seeders, Gandy fertilizer distributors and a Buffalo
turbine blower have been used to distribute dry materials. Slurry type
baits have been applied by a specially designed applicator which pumped
bait out each end of a 4.05 meter (10 ft.) boom and dropped the slurry
directly to the ground in strips 4.05 meters (10 ft.) apart (Lofgren et
al. 1961, Lofgren et al. 1963). Microencapsulated oil baits have been
applied with a specially designed spreader (Markin et al. 1969). This
apparatus was enlarged and adapted for aircraft application (Markin and
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Hill 1971). Banks et al. (1972) used aircraft equipped with the Texas
A&M type spreader and a special spreader from the Aircraft Operations
Section, Plant Protection Division, ARS-USDA.
Sampling: "--Control is usually determined by the percent reduction in
active mounds based on a pretreatment count of all active mounds in one
acre plots or .08 to .405 hectare (1/5 to 1 acre) subplots within larger
areas. Lofgren et al. (1963) considered mounds active if more than 20
workers or a wingless queen and less than 20 workers were found. Banks
et al. (1972) opened mounds with a shovel. Markin and Hill took pretreat-
ment counts, mapped all mounds and sampled at 10 and 22 weeks. Other
workers have increased sampling intensity beginning as early as 2 weeks
and continuing for up to 26 weeks.
Analysis and Reporting of Data:—Where possible, treatment means
should be compared using a valid statistical test for significance.
The following data should be reported:
Description of terrain and dominant vegetation including plant
height, density, stage and condition at time of treatment.
Insecticide formulation used, amount of active toxicant per
hectare, name, source, and composition of baits.
General weather conditions at time of application and rainfall during
evaluation.
Mound density and percent reduction in active mounds at intervals
after application.
EefeTences
Banks, W. A., G. P- Markin, J. W. Summerlin, and C. S. Lofgren. 1972.
Four Mirex bait formulations for control of red imported fire ant.
J. Econ. Entomol. 65:1468-70.
Lofgren, C. S., V. E. Adler, and W. F. Barthel. 1961. Effect of some
variations in forumlation or application procedure on control of the
imported fire ant with granular heptachlor. J. Econ. Entomol.
54:45-47.
Lofgren, C. S., F. J. Bartlett, and C. E. Stringer. 1963. Imported
fire ant topic bait studies: Evaluation of carriers for oil baits.
J. Econ. Entomol. 56:62-66.
Markin, G. P., C. J. Mauffray, and D. J. Adams. 1969. A Granular Appli-
cator for Very Low-volumes of Microencapsulated Insect Bait or Other
Materials. U. S. Dept. Agr. ARS (Ser.) 81-84. 4 p.
Markin, G. P., and S. 0. Hill. 1971. Microencapsulated oil bait for
control of the imported fire ant. J. Econ. Entomol. 64:193-196.
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-Black Grass Bugs - Ldbops and Irbisia
Grass bugs have been recognized recently as major pests of range grasses,
especially introduced species, in restricted areas of most of the western
states. Early symptoms of damage are yellow or whitish irregular spots on
the leaves which, with continued feeding, become more numerous, coalesce,
and the leaves dry out and die.
Crop Variety and Location of Tests: — Areas chosen should be represen-
tative of the region for which control recommendations are needed. Experi-
ments should be conducted on moderately to heavily infested range on which
the previous grazing history is known.
Experimental Design: — Since migration appears to be less than with
grasshoppers, plot size can be smaller. Plots of 12.2 x 12.2 meters (40 x
40 ft.), as recommended for plant bugs on alfalfa, should be adequate for
ground application. Kamm (personal communication) found 6.1 x 6.1 meters
(20 x 20 ft.) plots to be adequate; however, Haws (personal communication)
experienced difficulty with drift using 9.1 x 9.1 meters (30 x 30 ft.)
plots. A randomized complete block design with a minimum of three repli-
cates is recommended. Care should be exercised that drift does not affect
other treatments or the untreated check. The use of treated borders around
plots will reduce migration where this is a problem.
The minimum size for aerial application plots will be dictated by the
type of equipment used. The distance between plots or the width of plots
should be adequate to prevent drift as grass bug populations appear to be
very susceptible (Haws, personal communication).
Application and Equipment : — Low pressure low-volume boom type sprayers
can be used where terrain permits. Preliminary screening tests may be
conducted with knapsack or compressed air sprayers as long as coverage is
thorough. For aerial application, properly calibrated application equip-
ment designed and evaluated on the type of aircraft being used is recom-
mended. ULV formulations are usually the most suitable for aerial appli-
cation.
Sampling: — No -standardized one-step sampling technique has been de-
veloped which is effective for all instars. The standard 3.8 decimeter
(15 inch) insect net has been used for sampling adults and larger instars.
Sweep net samples vary in efficiency depending upon the growth habits of
the grass species being sampled. Temperature, time of day, cloud cover,
and other variables have a profound effect on the sampling under similar
conditions. Haws (personal communication) reports that disturbance of
the grass during sampling causes grass bugs to drop from the plants. Todd
and Kamm (1974) and Haws (personal communication) have used modifications
of a sampling cylinder from which specimens were aspirated and in some
cases the vegetation was also placed in Berlese funnels for further speci-
men recovery.
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Analysis and Reporting of Data:— Treatment means should be compared
using a valid statistical test For significance.
The following data should be reported:
Description of terrain and dominant vegetation, including plant
height, stage and condition at time of treatment.
Insecticide formulation used and amount of active toxicant per hectare.
Amount of spray per hectare, type of equipment and operating parameters.
Temperature and general weather conditions at time of treatment.
Rainfall amounts and interval from application, especially for first
24 hours.
Insect population counts recorded as number of insect per sweep or unit
of measurement in the vacuum net technique. The dominant species or species
composition of the grass bug population.
References
Haws, B. A. 1975. Professor of Entomology, Department of Biology, Utah State
University. Personal communication.
Haws, B. A., D. D. Dwyer, and M. G. Anderson. 1973. Problems with range
grasses: Look for black grass bugs. Utah Sai. Vol. 34 March.
Kamm, J. A. 1975. Research Entomologist, USDA, ARS, Department of Entomology,
Oregon State University. Personal communication.
Knowlton, G.F. 1966. Grass Bugs: Range and Crop Pest in Utah. Utah State
Univ. Ext. Serv. Entomol. Mimeo Ser. 119.
Knowlton, G. F. 1975. Professor of Entomology, Emeritus, Department of
Biology, Utah State University. Personal communication.
Todd, J. G., and J. A. Kamm. 1974. Biology and impact of a grass bug
Labops hesperius Uhler in Oregon rangeland. J. Range Manage. 27: 453-458,
Chigger, fleoschongastio Americana (Hirst) (Affectjpp Turkeys)
Kung et al. (1969) described the damage of this pest by stating, "The
chigger, Neosohongastia americana (Hirst) attacks turkeys in range pens in many
areas of the southern United States. Since the larva feeds at the site of
attachment, the area becomes inflamed and forms a purulent lesion. The lesion
causes a skin blemish which must be removed when the turkey is processed. The
necessary trimming causes the turkey carcus to be downgraded."
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Crop Variety and Location of Tes^ts_^—Since heaviest populations are
found on soils that tend to crack when dry and on soils with rock outcroppings,
these soil types should be selected. Sandy soils may not support adequate
populations for evaluation of insecticide efficacy (Price and Kunz 1970).
Experimental Design:—Chigger populations as determined by the number of
lesions per turkey are highly variable. At least three and preferably more
replicates are needed. Because of the habits of turkeys resting along the
edges of pens, 4.6 to 6.1 meters (15 to 20 ft.), treated borders are necessary
around the pens containing turkeys on the experimental plots.
Price and co-workers used wire pens of .0035 to .0034 hectare (1/116 to 1/120
acre) to confine 8 to 12-week old turkeys on treated areas. The plots were
cleared of vegetation prior to treatment. Treated barriers of 4.6 to 6.1
meters (15 to 20 ft.) were found to be required to achieve maximum control.
In other studies, .02 hectare (1/20 acre) pens stocked 10 turkeys, 22.8 x 22.8
meter (75 x 75 ft.) plots with pens 13.7 x 13.7 meters (45 x 45 ft.) stocked
with 50 turkeys and .405 hectare (one acre) plots with nine 4.3 x 4.3 meter
(14 x 14 ft.) pens stocked with three turkeys each and placed in an X configura-
tion within the plot, were used (Price and Kunz 1970, Price et al. 1970).
Replicated untreated check plots should be included in the experimental
design. Experiments may need to be designed to evaluate serial treatments
on the same plot.
Application Equipment:—Small plots have been treated with water sprinkling
cans for liquids, fabricated shakers for granules and commercially made portable
hand dusters. Larger plots have been treated with pressure spravers at 8.8-
10.6 kg/cm2 (125-150 psi) at the rate of 3741.6 liters/ha (400 gal. of water/
acre). (Price and Kunz 1970, Price et al. 1970).
Sampling:—Indirect counts, based on the number of chigger lesions per bird
were used in the studies cited above.
The number of lesions on the drumsticks, thighs and breast areas were
counted for each bird. Counts were made weekly for 7 to 20 weeks. Price et al.
(1970) did not make weekly counts; instead, grade as determined by a Federal
meat inspector was used as the criterion of success or failure of the
insecticide.
Analysis and Reporting of Dataj-r-Treatment means should be compared using
a valid statistical test for significance,
The following data should be reported:
Insecticide formulation used and amount of active toxicant per hectare.
Amount of spray, dust or granules per hectare and the type of equipment
used.
Plot size and lay out, including any special vegetation clearing and
number and age of turkeys stocked.
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Temperature and general weather conditions at the time of treatment.
Rainfall amounts and intervals after treatment.
Number of lesions per bird or other index of infestation in treated
and untreated plots at each sampling interval.
References
Kunz, S. E., M. A. Price, and 0. H. Graham. 1969. Biology and economic
importance of the chigger, Neoschongastia americana on turkeys. J.
Econ. Entomol. 67-872-875.
Price, M.A. 1975. Professor of Entomology, Department of Entomology, Texas
A&M University. Personal communication.
Price, M.A., and S. E. Kunz. 1970. Insecticidal screening for chemicals to
control the chigger, Neoschongastia ameri-cana (Hirst) on turkeys. J-
Econ. Entomol. 63:373-6.
Price, M.A., S.E. Kunz, and Jesse J. Matter. 1970. Use of Dursban to control
Neoschongast-ia ccreT-ioana, a turkey chipger „ ir experimental pens. J'.
Econ. Entomol. 6°-377-379.
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VEGETABLES (FIELD GROWN)
CRUCIFERAE
Crops in this group include: Cabbage - Brassica oleracea var. capitata:
Broccoli - Brassica oleracea var. botrytis- Cauliflower - Brassica oleracea
var. botrytis; Brussels sprouts - Brassica oleracea var. germifera; Kale -
Brass-Lea oleracea var. ocephala; Collards - Brassica oleracea var. virdis:
Turnip - Brassica campestris var. rapa; Mustard - Brassica juncea var.
crispifolia; Spinach - Spinacia oleracea.
Cabbage Looper (//I) Trichoplusia ni (Hubner) and Associated Insects
The cabbage looper, Trichoplusia ni (Hubner), is without question the
number one pest of this group. During the 1950's and much of the 1960's,
growers of these crops in many sections of the country were without adequate
looper insecticides. Residue problems, precluding the release of new chemicals
and removal of some previously labeled, the development of resistance and
higher consumer standards—all contributed to an almost untenable situation.
With the appearance of improved strains of the safe bacterium, Bacillus
thuringiensis Berliner, and approval of new insecticides such as methomyl
and methamidophos there is now hope of eventual success in looper control. In
addition, the use of viruses, sex attractants, chemosterilants and other
physiological and biological methods show great promise for the future.
However, constant investigations for improved measures against loopers are
necessary and will continue to be one of the most active areas in insect
control.
Although test procedures for cabbage loopers will be stressed, there are
a number of other insects that may be sampled and recorded using the same basic
test structures. "Some of these associated pests are as follows: Imported
cabbage worm, Pieris rapae (Linnaeus): diamondback, Plutella xylostella
(Linnaeus): fall armyworm, Spodoptera frugiperda (J.E. Smith): beet armyworm,
Spodoptera exigua (Hubner): Garden webworm, Loxostege rantalis (Guenee),
Hawaiian beet webworm, Hymenia recurvalis (Fabricius), and corn earworm,
Heliothis zea (Boddie).
Both foliage sprays and systemic granulars applied to the soil will be
covered.
Crop and Location of Tests:—Select a variety or varieties commonly
grown in the area in question. A uniform test is desirable since the degree
of control or plant response may vary in different soil types. Follow proven
planting techniques and cultural practices.
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Experimental Design:—
Ground Application-A randomized complete block design with three or more
replications per treatment is suggested. Ideally, candidate insecticide
performance should be compared with untreated plots and one or more standard
insecticides recommended for the area in question. However, if it is impossible
to have untreated controls, it should be sufficient to compare the treatments
with one or more of the recommended standards.
Plot size may vary greatly depending on the uniformity of infestation
and population density. A number of investigators have used single row
7.6-15.2 m (25-50 ft.) long plots with success: Boling (1972), Chalfant and
Brett (1965), Chalfant et al. (1973), Creighton et al. (1971, 1974) and
Shorey (1963). Kouskolekas and Harper (1973) utilized 9.1-12.2 (30-40 ft.)
long plots with 4-5 rows. Davis and Kuhr (1974), Greene and Workman (1971),
and Judge and McEwen (1970) made observations on multiple row 15.2 m (50 ft.)
long plots.
One or more adjacent untreated rows would appear to be essential to 1
and 2 row plots and highly desirable in larger test areas. Davis and Kuhr
(1974) planted 2 rows of corn next to their 2 row plots. Hofmaster and
Waterfield (unpublished data at the Virginia Truck and Ornamentals Research
Station, Painter, Virginia) worked with 1-3 row plots 10.7-15.2 m (35-50 ft.)
long which were bounded by 1-3 untreated rows, thereby affording increased
insect pressure and minimizing cross contamination.
Aerial Application-A minimum of 2 and preferably 3 swaths, each 12.2 m
(40 ft.) wide or covering a comparable area is suggested to prevent drift and
have sufficient area in the middle of the plot to collect representative
samples. The length should be sufficient to enable the pilot to fly level
and safely over the plots for at least 182.6 m (600 ft.).
Application and Equipment:—Both sprays and granular applications should
be utilized in investigating insect control and can be adapted to most of the
species concerned.
2
Ground Application-Knapsack sprayers operating at 2.1-4.2 kg/cm (30-60
psi) and delivering 187.1-935.4 liters/ha (20-100 gallons of water/acre) will
give satisfactory results (Shorey 1963, Creighton et al. 1971). Calibrate
the sprayers carefully and apply the spray along each side of the row and
over the top. Where single nozzles are used this will require a trip along
each side and back over the top. Backpack sprayers may have a spray boom
equipped with 3 nozzles per row. These nozzles should be adjusted so as to
cover the top 'and sides of each row (Fofmaster and Waterfield 1972).
In moving to mechanized equipment, a wide variety of pressures and rates
are encountered, e.g., Judge and McEwen (1970) 261.9 liters/ha (28 gallons/
acre) at 4.2 kg/cm2 (60 psi): Greene and Workman (1971) 935.4 liters/ha at
17.6 kg/cm2 (250 psi): and Kouskolekas and Harper (1973) 935.4 liters/ha
(100 gallons/acre at 38.7 kg/cm2 (550 psi)). Generally speaking, the type of
application equipment is of secondary importance if good coverage is obtained.
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When working with large plots it is suggested that the treatments be
applied with equipment that is adaptable to that particular locality. Such
procedure will do much to decrease the danger of subsequent failure should
a product be labeled for a given method that is not generally followed
or cannot be followed in a particular section.
Granules may be applied by a variety of methods. One of the most
commonly used is as a soil sidedress, either at planting, transplanting, or
later in the season. Commercial applicators may be used satisfactorily.
Calibrate the applicator carefully for each formulation and then treat
directly without resetting. Hale and Shorey (1972) applied granules with a
tractor-mounted belt planter by side-dressing 7.6-10.2 cm (3-4 in.) from the
plant row and 5.1-7.6 cm (2-3 in.) deep. Plants were 7.6-15.2 cm (3-6 in.)
high at the time of planting and irrigation was applied within 24 hours.
Aerial Application-Use nozzle arrangement and volume of finished spray
determined to be practical under existing conditions. In most areas the spray
volume will range from 18.7-93.5 liters/ha (2-10 gallons/acre) although good
control has been obtained with lower or higher dosages.
Regardless of the method of application, the equipment should be
thoroughly cleaned before each use. When changing treatments, the tank, boom
and nozzles should be rinsed with water run through the entire system until it
is clear.
If more than one rate (kg/ha or Ibs/acre) of toxicant is used, start the
test seciuences with the lowest rate thereby keeping the chances of contamination
at a minimum. Generally, several rates should be applied when testing is in
the initial phase. After the rate or rate range is established and testing
is in the final stages, emphasis should be placed on the probable rate or rates
to be used.
Sampling:—Make direct counts of larvae, checking at least 10-25 plants or
parts therefrom/plot (Creighton et al. 1971, 1974, Chalfant and Brett 1965,
Chalfant et al. 1973, Greene and Workman 1971). A clearer understanding will
be obtained if the surviving loopers are grouped according to size. Hale' and
Shorey (1972) recorded the loopers as: small (1st stage): medium (2nd to
early 4th); and large (late 4th and 5th stages) .
Be prepared to supplement direct counts with ratings of injury. This
can be especially important when a naturally occurring nuclear polyhedrosis
virus decimates the existing population in a space of 4-5 days (Hofmaster 1961).
Various ratings may be employed: Kouskolekas and Harper (1973) adopted
a 1 to 10 scale; Greene et al. (1969) working on a cooperative cabbage looper
control program in Florida used a damage rating scale of 1 to 6; Greene and
Workman (1971) adapted this 1 to 6 rating on a leaf crop (collards) • Creighton
and McFadden (1974) examined the edible leaves of each plant (collards) , record-
ed the number of injured and uninjured leaves, and used these to calculate
the percentage of plants that were either uninjured or had 1 leaf, 2-10 leaves
or more than 10 leaves injured; and Ratcliffe et al. (1961) adapted a weighted
injury index in which values were assigned to various classes of injury,
multiplied by the number of plants in that class and divided by the total
number of plants checked. Whatever the rating method, be explicit. Do not
use terminology such as medium, severe, etc. without clearly spelling out
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just what these terms encompass.
Take yield records, carefully noting the extent of injury to the marketable
parts of the plant at harvest. Records may be taken from the entire plot or
representative section therefrom. Separate crop into marketable and unmarketable
classification similar to the method of Reid (1940) for cabbage: Class 1 -
head and 4 wrapper leaves free of all feeding; Class 2 - plants with some
caterpillar injury but eligible to U.S. Grade 1: and Class 3 - head and 4
wrapper leaves extensively damaged by feeding and ineligible to U.S. Grade 1.
Analysis and Reporting of Data:—Compare treatment means using a valid
statistical method such as Duncan's multiple range test. Candidate insecticide
performance should be compared with replicated untreated plots and one or more
standard insecticides recommended for the area. Where it is impossible to
leave untreated areas, comparison with one or more standard insecticides should
suffice.
The following data should be reported:
1. Pre-test counts to determine approximate level of the population prior
to treatment. It is realized that this will not be possible for some types of
insects.
2. Insecticide formulation used and kilograms active toxicant/hectare
(Ibs active/acre). Describe application equipment, quantity delivered, pressure,
etc.
3. Insect populations and stage of plant growth on given date, listing
sampling technique.
4. Plant height, stage and condition at time of treatment and sampling.
5. Temperature, humidity, rainfall and general weather conditions at
treatment. Record these for all application dates and all except humidity for
the sampling dates. Overall weather records for the entire test period may be
useful.
6. Percent organic matter and type of soil.
7- Plant response, phytotoxicity or obvious defects in the harvested crop.
Harlequin Bug (Murgantia histrionica) (Hahn)
The harlequin or "fire bug," Murgantia histrionica (Hahn), has been called
the most important insect enemy of cabbage, collards and related crops in the
southern half of the U.S. It sucks the sap from the plants, injecting toxic
saliva and apparently poisoning them as it does so, as damage is far out of
proportion to the number of bugs or juices withdrawn. Damage first appears as
chlorotic spots but these areas soon turn brown and die. Severely injured
plants wither and appear as if scalded. Published references concerning
harlequin control are quite limited.
Sampling:—Make direct counts of both adults and nymphs on 10-25 plants/
plot, keeping the two classes separate. Where populations are low, 50 or more
nymphs may be carefully counted on the plants, the section of the row can be
isolated and the treatments applied (Hofmaster 1959) for determining mortality.
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Supplement with observations on the number of characteristic keg-shaped
egg masses.
Record plant condition throughout the season; either through ratings
or actual counts of the harlequin bugs or their feeding scars.
Collect yield records. Record marketable and unmarketable heads or
leaves and their weights. Yields may be from the entire plot or representative
sections therefrom.
Flea Beetles
A number of species of flea beetles attack crops of this group. The striped
cabbage flea beetle, Phyllotreta striolata (Fabricius)r the western striped
flea beetle, Phyllotreta rcanosa (Crotch); the western black flea beetle,
Phyllotreta pusilla (Horn); the sinuate striped flea beetle, Phyllotreta
sinuata (Stephens): and the spinach flea beetle, Disonycha xanfhomelas
(Dalman) are some of these.
Flea beetles vary greatly in life history and while the larvae of most
species develop in the soil, some of the young feed on or in the foliage.
Examples of foliage feeding larvae include the sinuate striped flea beetle
and spinach flea beetle. Although the flea beetle larvae cause damage, most of
the injury is by the adults. Seedling plants of this group are especially
vulnerable to damage by flea beetles and plant stands may be seriously reduced
in a day or so.
Sampling:—Select at least 25 leaves/plot and count the flea beetle feeding
scars thereon. If damage is heavy, count uniform sections of the leaf. Some
investigators such as Ratcliffe et al. (1961) prefer to count all the beetles on
a plant but this is difficult unless a sampling cage (Hills 1933) is used.
Make larval counts of species that develop on the foliage. Sweeping is discouraged
as an accurate means of evaluation.
On seedlings, count the number of injured plants/0.305 m (1 ft.) of row.
Stand counts may be needed where infestations are severe. If the plants have
several leaflets it may be possible to check 100 or more leaflets/plot. On calm
days, actual counts of beetles/10-25 samples of 0.305 m (1 ft.) of row may be
advantageous. A sampling cage (Hills 1933) may be used to advantage.
Take yields, using methods that are most appropriate for the crop. Yields
may be from the entire plot or representative areas therefrom.
References
Boling, J.C. 1972. Insecticidal control of the cabbage looper in small field
plots. J. Econ. Entomol. 65(6):1737-1738.
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Chalfant, R.B., and C.H. Brett. 1965. Cabbage looper and imported cabbage-
worms: feeding damage and control on cabbage in western North Carolina.
J. Econ. Entomol. 58(l):28-33.
Chalfant, R.B., W.G. Genung, and R.B. Workman. 1973. Control of the cabbage
looper in Florida and Georgia. J. Econ. Entomol. 66(1) -.276-277.
Creighton, C.S., and T.L. McFadden. 1974. Complimentary actions of low rates
of Bacillus thuringiensis and chlordimeform hydrochloride for control of
caterpillars on cole crops. J. Econ. Entomol. 67(1):102-104.
Creighton, C.S., T.L. McFadden, and R.B. Cuthbert. 1971. Control of the
cabbage looper, Trichoplusia ni, and of two associated caterpillar species
on cabbage with Bacillus thuringiensis and chemical insecticides. J. Ga.
Entomol. Soc. 8(2):132-136.
Creighton, C.S., T.L. McFadden, and R.B. Cuthbert. 1974. Chemical Insecticides:
Field Evaluation for Control of Cabbage Caterpillars. ARS-S-32, March 1974,
6 pages.
Davis, A.C., and R.J. Ruhr. 1974. Laboratory and field evaluation of methomyl's
toxicity to the cabbage looper. J. Econ. Entomol. 67(5):681-682.
Greene, G.L., W.G. Genung, R.B. Workman, and E.G. Kelsheimei*. 1969. Cabbage
looper control in Florida - A cooperative program. J. Econ. Entomol.
62(4):798-800.
Greene, G.L., and R.B. Workman. 1971. Cabbage looper control on collards in
Florida. J. Econ. Entomol. 64(5):1331-1332.
Hale, R.L., and H.H. Shorey. 1972. Cabbage looper control on cole crops in
southern California: Granular insecticides in the soil indicate lack of
promise. J. Econ. Entomol. 65(6):1658-1661.
Hills, Orin A. A new method for collecting samples of insect populations.
J. Econ. Entomol. 26(4) :906-910.
Hofmaster, R.N. 1959. Effectiveness of new insecticides against the Harlequin
cabbage bug on collards. J. Econ. Entomol. 52(4) -.777-778.
Hofmaster, R.N. 1961. Seasonal abundance of the cabbage looper as related to
light trap collections, precipitation, temperature and the incidence of a
nuclear polyhedrosis virus. J. Econ. Entomol. 54(4):796-798.
Hofmaster, R.N., and R.L. Waterfield. 1972. Insecticide control of the potato
tuberworm in late crop potato foliage. Am. Potato J. 49:383-390.
Judge, F.D., and F.L. McEwen. 1970. Field testing candidate insecticides on
cole crops for control of cabbage looper and imported cabbageworm in New
York State. J. Econ. Entomol. 63(3) :862-866.
Kouskolekas, Costas A., and James D. Harper. 1973. Control of insect
defoliators of collards in Alabama. J. Econ. Entomol. 66(5):1159-1161.
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Ratcliff, R.H., L.P. Ditman, and T.J. Whitlaw, Jr. 1961. Field experiments on
insecticidal control of insect pests of cabbage and broccoli. J. Econ.
Entomol. 54(2)=356-359.
Shorey, H.H. 1963. Field experiments on insecticidal control of lepidopterous
larvae on cabbage and cauliflower. J. Econ. Entomol. 56(6):877-880.
CRUCIFERAE AND HEAD LETTUCE
Aphids and Thrips
Crop and Location of Tests:—Select a crop variety that is grown
commercially in a suitable test area that is protected from pesticide drift
from any adjoining fields, i.e., having the test area upwind from the adjoining
field should be sufficient. Aphids and thrips should be considered economical-
ly important in the test area.
The plot size should depend on the stage of pesticide development. In
the early stages small hand and ground equipment applications will suffice to
demonstrate efficacy. Plots one row wide by 7.6-15.2 tn (25-50 ft.) long with
1-2 untreated buffer rows between each plot should be large enough for small
"screening" tests.
In the final stages of pesticide development the plot size should be
larger to more closely resemble the commercial ground and air applications,
and large enough to prevent drift from adjacent plots from influencing the
results in the sampling area.
Since most commercial plantings of cruciferae and lettuce are double
row beds, it is suggested that experimental pesticide plots be conducted on
double row beds as it is much more difficult to obtain coverage in comparison
to single row beds. Most commercial ground applicators treat 6-8 beds per
swath, therefore, plots should be 12-16 beds wide by 18.3 m (60 ft.) long.
Air plots should be 36.6 m (120 ft.) wide or 3 swaths 12.2 m (40 ft.)
in width to prevent drift and to have enough area in the middle of the plots
to make aphid and thrip counts over a wide area. The length must be long
enough to enable the pilot to fly level and safely over the plots for at least
182.9 m (600 ft.).
Experimental Design:—Use a randomized complete block design. Use at
least three replications when applied by ground equipment. When applied by
air, two replications will suffice when populations of aphids (apterous) and
thrips are fairly evenly distributed throughout the test area. However, more
replications should be used whenever possible.
Plots should be staked and mapped in any numbering system that will
conceal as much as possible the identity of individual treatments when plot
evaluations are made. One suggested method would be to number and stake the
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plots in consecutive order. (For example, 1-30.) Then give each treatment
a letter that would correspond to two or more of the numbered plots, depending
on the number of replications. Treatment "a" for example might be applied in
plot 3, 11, etc.
Application and Equipment:—Untreated controls should be used to determine
the aphid and thrip severity and to provide a basis of comparison of the
treatments. Also apply the recognized standard to provide a basis of comparison.
If it is impossible to have untreated controls because of the large acreage
involved, it should be sufficient to compare the treatments with one or more
acceptable standard materials.
Equipment should be thoroughly cleaned before each use. Between each
treatment the tanks, boom and nozzles should be rinsed and clean water run
through the system until the water comes out clear. If more than one rate
(AI/A) of the same material and the same formulation are being tested, start
the test sequence with the lowest rate so that the chances of contamination
are kept at a minimum.
A row crop boom attached to any acceptable foliar spray ground equipment
should be used for proper coverage. There are many types of spray tips that
can be used. It is suggested thatconejet cone spray tips (TX series) be used
when low capacity spray volume is needed. The small particle size provides
maximum distribution of the pesticide. When higher pressures and flow rates are
needed, then the disk cone spray tip should be used. There are situations when
the best method is a flat fan type tip directed over the center of the plant row.
This will provide deeper penetration into the plant foliage. The drop side
spray tips could then be the disk type. The nozzles can be mounted on drop
pipes suspended from the boom. Three nozzles per row is suggested when plants
are small. As the plants grow, the number of nozzles should increase to provide
optimum coverage. Regardless of the number of nozzles per row, the spray
pattern from the side tips should be directed in such a way as to apply as much
pesticide as possible to the underside of the leaves. When small screening
tests are applied, knapsack sprayers operating at 2.1-4.2 kg/cm (30-60 psi)
will give satisfactory results. The boom should have 3 nozzles per row. Air
application equipment should be commercially acceptable.
Granules-Many methods of granule placement are possible. It is suggested
that two methods be used. Placing the granules directly in the furrow at
planting time, or applied as a side-dress (with fertilizer saves labor costs)
7.6-10.2 cm (3-4 in.) deep and 5.1-10.2 cm (2-3 in.) to one side of the plant
row.
The rate of application is dependent on the stage of pesticide development.
Two to three rates (AI/A) should be used when testing is in its initial phase.
After the most efficient rate has been established and the pesticide is in the
final stages of development, then emphasis should be placed on the probable
rate or rates (AI/A) to be used.
The finished spray volume per acre would be dependent on the size of the
lettuce plants. When foliar spray is applied by small hand or large ground
equipment, 113.6-227.1 liters/ha (30-60 gals./acre) will give satisfactory results,
When foliar spray is applied by air, 37.9-56.8 liters/ha (10-15 gals/acre) will
provide good results.
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The time of application should be when aphids and thrips first appear in
any numbers that represent fairly closely an economic infestation.
Since the control of aphids and thrips mostly requires a remedial type
treatment or treatments, the testing of pesticides to control aphids and thrips
is a "one application" type screening method. The second application, if
requested, would follow when the effectiveness of the initial application is
gone.
One to three days is suggested as the initial interval between treatment
and observations, and then every 4-7 days thereafter until control in all plots
is no longer considered economic, unless of course specific intervals are
requested.
Sampling:—Count the total number of apterous aphids on 5-10 plants per
plot. The number of plants would depend on the severity of the infestation.
The small size and quick movement of thrips prevent the use of accurate visual
leaf counts. More than one method of counting thrips can be used, including
shaking the plants over jars containing alcohol and selecting leaves at
random and placing them in alcohol jars for counting in the laboratory. It is
suggested that the best method would be the use of a "Burlese." This would
involve selecting plants or leaves at random and placing them in the burlese
where heat and light drive the thrip from the leaves down to the alcohol jars
where they can be counted at the convenience of the investigator. This method
can also be used for aphids and gives more accuracy to the data. When making
counts, care should be taken to keep within a well buffered zone. When
examining small single row hand plots, keep at least 1.5 m (5 ft.) away from
the end of the plot.
The crop on which any new pesticide is being tested should be examined at
least once to determine if there is any deterimental effect on yield. This is
especially important when the pesticide is applied during the early stages of
plant development. All mature cruciferae and lettuce heads in a given area of
the central part of the plot should be harvested. Marketable heads should be
put in field cartons and the data converted to "yield in cartons per hectare
(acre)."
Any type of phytoxicity such as stunting, leaf burn and chlorosis and
the percent of damage should be reported.
Analysis and Reporting of Data:—Data means should be compared using any
valid statistical test for significance such as Duncan's new multiple range
at the 5% level.
The following information should be included in reporting test results:
Product name and formulation used.
Crop (variety) treated.
Location of the test.
Type of irrigation used (furrow or sprinkler).
Plot size.
Number of replications.
Active ingredient kg/ha (Ib/acre).
Finished spray volume 1/ha (gal./acre).
Method of application.
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Stage of crop growth.
Treatment dates.
Evaluation technique.
Sampling technique.
Number of samples taken.
Total insect counts per plot.
Phytotoxicity.
Comments regarding unusual test conditions or performance.
Temperature and general weather conditions at time of treatment.
Rainfall or any unusual weather conditions following the application.
Include comment on performance as related to commercial acceptability.
Statistical analysis.
References
Hale, R.L. 1967-1973. Annual reports on file with the Entomology
Department, University of California, Riverside, California.
Hale, R.L. 1973-1974. Unpublished data.
Hall, I.M., R.L. Hale, H.H. Shorey, and K.Y. Arakawa. 1961. Evaluation of
chemical and microbial materials for control of the cabbage looper.
J. Eoon. Entomol. 54(1):141-146.
McCalley, N.F., and Der-I-Wang. 1972. Field evaluation of insecticides
for control of the green peach aphid and alfalfa looper on head lettuce,
J. Eoon. Entomol. 65(3):794-796.
Shorey, H.H., and I.M. Hall. 1962. Effect of chemical and microbial
insecticides on several insect pests of lettuce in Southern California.
J. Eoon. Entomol. 55(2):169-174.
Cabbage Looper (#2) Trichoplusia ni (Hubner)
Most of the following methodology will also apply to the following pests
on cruciferae and head lettuce: imported cabbageworm, armyworms, diamond-backs,
and beet armyworms.
Crop and Location of Tests:—See statement under Aphids and Thrips.
Only modifications are noted below.
In the early stages of pesticide testing, small hand and ground equipment
applications would suffice to demonstrate efficacy. Plots one row wide by
7.6 m (25 ft.) long with 1-2 untreated buffer rows between each plot should be
large enough since the cabbage looper larva is not very mobile and is very
difficult to kill.
Since most commercial ground applicators treat 6-8 beds per swath, plots
should be 6-8 beds wide by 15.2-18.3 m (50-60 ft.) long.
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Even though treatments by air are not as effective as by ground applications,
they do occur and are necessary under conditions of wet fields, etc. Test plots
by air should be 36.6 m (120 ft.) wide (3 swaths 12.2 m (40 ft.) in width) to
prevent drift, and long enough to enable the pilot to fly level and safely
over the plots for at least 182.9 m (600 ft.).
Experimental Design:—See statement under Aphids and Thrips, substitute
"larvae" for "aphids (apterous) and thrips."
Application and Equipment:—Only deviations from Aphids and Thrips are
noted below.
No method of placing systemic granules in the soil for cabbage looper
control has proven to be economically satisfactory. There are many reasons
for failure and most can be found by consulting the literature.
The time of application should be when cabbage loopers first appear in any
numbers that represent fairly closely an economic infestation. Preferably
the population should include small, medium and large size worms. This
procedure will test the efficacy of the pesticide against as many stages of
the cabbage looper larvae as possible.
Normally, one, three and seven days is suggested as the interval between
treatment and observations for the first 3 evaluations and then every 5-7
days until control in all plots is no longer considered economic. This method
will provide information on quick initial kill and the longevity effectiveness
of the pesticide.
Sampling:—Count the total cabbage looper larvae on at least 10 plants
per plot. (If replicated 4 times, this would mean 40 plants per pesticide
treatment.) Care should be taken when examining small single row hand plots
to keep at least 1.5 m (5 ft.) away from the end of each plot. When plots
are commercial ground or air, keep within a well buffered zone.
A better understanding of the effect of each pesticide tested will be
obtained if the surviving cabbage looper larvae are counted according to
size: Small (1st stage); medium (2nd to early 4th stages); and large (late 4th
and 5th stages).
See also the statement under Aphids and Thrips for information concerning
yield data and phytotoxicity.
Analysis and Reporting of Data:—See statement under Aphids and Thrips.
References
Boling, J.C. 1972. Insecticidal control of the cabbage looper in small field
plots. J. Econ. Entomol. 65(6):1737-1738.
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Hale, R.L., and H.H. Shorey. 1972. Cabbage looper control on cole crops in
Southern California: Granular insecticides in the soil indicate lack of
promise. J. Econ. Entomol. 65(6):1658-1661.
Hale, R.L. 1967-1973. Annual reports on file with the Entomology Department,
University of California, Riverside, California.
Hale, R.L. 1973-1974. Unpublished data.
Hall, I.M., R.L. Hale, H.H. Shorey, and K.Y. Arakawa. 1961. Evaluation of
chemical and microbial materials for control of the cabbage looper.
J. Econ. Entomol. 54(1):141-146.
Shorey, H.H., and R.L. Hale. 1963. Field experiments on insecticidal control
of lepidopterous larvae on cabbage and cauliflower. J. Econ. Entomol.
56(6):877-880.
Shorey, H.H., and I.M. Hall. 1962. Effect of chemical and microbial
insecticides on several insect pests of lettuce in Southern California.
J. Econ. Entomol. 55(2):169-174.
Shorey, H.H., and R.L. Hale. 1965. Cabbage looper, a principle pest of
agricultural crops in California. Calif. Agric. 19(3):10-11.
Shorey, H.H., and R.L. Hale. 1967. Evaluation of systemic insecticides
incorporated in the soil for control of lepidopterous larvae on cole
crops in Southern California. J. Econ. Entomol. 60(6):1567-1570.
CUCURBITS
Crops in this group include: Cantaloupe - Cucwnis melo var. cantalupenis:
Cucumber - Cucumis sativus; Pumpkin - Cucurbita pepo; Squash - Cucurb-ita maxima;
and Watermelon - Ci-trullus vulgaris.
Cucumber Beetles
At least five species of cucumber beetles infest cucurbit plantings in
different areas. These are as follows: striped cucumber beetle, Acalymma
vittata (Fabricius) ; spotted cucumber beetle, Diabrotica undecimpunctata howardi
Barber; western spotted cucumber beetle, Viabrotica undecimpunctata undecimpunctata
Mannerheim; western striped cucumber beetle, Acalymma trivittata (Mannerheim);
and the banded cucumber beetle, Diabrotica balteata LeConte. All have similar
habits and life cycles but, in general, the striped cucumber beetle causes more
overall injury to cucurbits by direct feeding and transmitting bacterial wilt.
Due to the wide distribution and importance of cucumber beetles, test methods
for this group will be described first; with slight modifications they can be
adapted for other cucurbit pests.
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Crop and Location of Tests:—Select a variety or varieties of cucurbits
commonly grown in the same geographic area. Brett and Sullivan (1970) have
demonstrated a variation in insect susceptibility among cucurbits. If the
information is available, plant a more susceptible variety. Follow proven
planting and cultural techniques for the area.
Experimental Design:—
Ground Application-A randomized complete-block design with three or more
replications is suggested. Ideally, candidate insecticide performance should be
compared with untreated plots and one or more standard insecticides recommended
for the area in question. However, if it is impossible to have untreated
controls, it should be sufficient to compare the treatments with one or more
recommended insecticides.
Plot size may vary greatly, depending on the anticipated uniformity of
infestation, stage of insect and population density. The following references
to plot size are not limited to cucumber beetle investigations but include
other cucurbit pests.
Gould (1969), who has conducted extensive cucumber beetle investigations,
adapted single row 10.7 m (35 ft.) long plots in rows planted 193-203.2 cm
(76-80 in.) apart. Waites and Habeck (1968) treated plots 7.6 m (25 ft.) long
by 4 rows wide, while Canerday (1967) selected the same length but varied from
1-3 rows. Roberts and Anderson (1960) used 8 row wide plots 9.1 m (30 ft.) in
length. Staples et al. (1967) employed plots 9.1 m (30 ft.) long by 4.6 m
(15 ft.) wide containing 12 hills with 3-5 plants/hill. Researchers such as
Wright and Decker (1955) used large scale field length plots ranging from
4-16 rows in width.
Aerial Application-A minimum of 2 and preferably 3 swaths each 12.2 m
(40 ft.) wide or covering a comparable area is suggested to prevent drift and
to have sufficient area in the middle of the plot to collect representative
samples. The length should be sufficient to enable the pilot to fly level
and safely over the plots for at least 182.6 m (600 ft.)
Application and Equipment:—Both liquid and granular applications should
be considered in investigations of cucurbit insect control and can be adapted
to most of the species concerned.
Ground Application-Knapsack sprayers operating at 2.1-4.2 kg/cm2 (30-60 psi)
and delivering 187.1-935.4 liters/ha (20-100 gallons/acre) will give
satisfactory results. (Canerday 1967, Fisher 1965.) Calibrate the sprayers
carefully and apply the spray along each side of the row and over the top.
Where single nozzles are used, this will require a trip along each side and
back over the top. Backpack sprayers may have a boom equipped with 3 nozzles/
row. Regardless of the crop involved, the nozzles should be adjusted so as to
cover upper and lower leaf surfaces (Hofmaster and Waterfield 1972) .
Due to the many variations possible in spraying techniques on cucurbits,
no attempt will be made to standardize, especially in field scale plots. The
most practicable end results for large plots will be obtained by utilizing
commercial spray practices best adapted to the crop and area concerned.
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Regardless of the type of equipment used, repeated and early applications
are necessary for the control of cucumber beetles and subsequent reduction of
bacterial wilt. For example, Gould (1969) treated the following days after
plant emergence: 2, 5, 8, 12, 17 and 24.
Aerial Application-Use nozzle arrangement and volume of finished spray
determined to be practical under existing conditions. In most areas the spray
volume will range from 18.7-93.5 liters/ha (2-10 gallons/acre) although good
insect control has been obtained with lower or higher dosages.
Granules may best be applied with a commercial granular applicator
although successful tests have been conducted using a simulated applicator
technique (Gould 1969). Be sure to place granules in the same relative position
consistently and study placement in detail as much information is needed.
Calibrate the granular applicator carefully for each formulation and rate and
then treat directly without resetting.
Note: Bees are extremely valuable and essential as pollinators of cucurbits.
The effect of the test chemical on the bees should be determined insofar as
possible. Harm to the bees will be reduced if treatments are made towards
evening.
Regardless of the method of application, the equipment should be
thoroughly cleaned before each use. When changing treatments, the tank, boom
and nozzles should be rinsed with water run through the entire system until it
is clear.
If more than one rate (kg/ha or Ibs/acre) of toxicant is used, start
the test sequences with the lowest rate thereby keeping the chances of contamina-
tion at a minimum. Generally, several rates should be applied when testing
is in the initial phase. After the rate or rate range is established and
testing is in the final stages, emphasis should be placed on the probable rate
or rates to be used.
Sampling:—Evaluations may require a wide variety of observations.
Overwintered Beetles-These beetles work down to the germinating cucurbits
and often clip them below ground level. In addition, they transmit bacterial
wilt and mosaic and carry the diseases from field to field. Early season
control is most important since the bacterial wilt overwinters in the beetles
and they are infective at the first feeding.
Make direct counts of overwintered beetles per 10-25 hills/plot. Record
bacterial wilt and mosaic as they occur. Gould (1969) measured the average
length of vines at thinning time and also checked the incidence of bacterial
wilt. Staples et al. (1967) developed a portable cage, with the counter inside,
for determining adult populations.
Larvae-If plants appear to be in poor condition later in the season and
do not have obvious wilt, it may be from larval damage to the roots. Examine
5-10 hills/plot.
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New Adults-Adults present as the fruit nears maturity often gnaw holes
in the skin or rind and otherwise scar the fruit. Examine 10-25 fruit/plot,
taking special care to check the area in contact with the soil.
Record number and weight of fruit for at least 3 harvests. Records may
be taken from'the entire plot or representative section therefrom.
Analysis and Reporting of Data:—Compare treatment means using a valid
statistical method such as Duncan's multiple-range test. Candidate insecticide
performance should be compared with replicated untreated plots and one or more
standard insecticides recommended for the area in question. Where it is
impossible to leave untreated areas, comparison with one or more standard
insecticides should suffice.
The following data should be reported:
1. Pre-test counts, where feasible, to determine approximate level of
the insect population prior to treatment. It should be pointed out that this
is not possible for some types of insect infestations.
2. Insecticide formulation used and kilograms active toxicant/hectare
or Ibs. active/acre. Describe application equipment, gallonage, pressure,
etc.
3. Insect populations and stage of plant growth on given date, listing
sampling technique and units of measurement.
4. Plant height, stage and condition at time of treatment and sampling.
5. Temperature, humidity, rainfall and general weather conditions at
treatment. Record these for all applications and all except humidity for the
sampling dates. Overall weather records for the entire test period may be
useful.
6. Percent organic matter and type of soil.
7. Plant response, phytotoxicity or obvious defects in the harvested
crop.
Squash Bug, Anasa tri,st-is (De Geer)
The squash bug, Anasa tristis De Geer, is a very difficult insect to
control. Leaves of attacked plants wilt rapidly, resulting from toxic
salivary secretions and appearing almost as though they were literally
strangled or poisoned. The margins of the leaves soon become crisp and dead
and whole plants may be killed. Later on the fruit is attacked, especially
squash and pumpkin in the fields after frost has killed the vines.
Sampling:—Evaluation of squash bug populations is difficult in the
adult stage early in the season. Nymphal counts are easier to make and much
more accurate overall. Fisher and Green (1965) successfully combined adult
and nymphal counts.
Examine 10-25 plants/plot for evidences of adult feeding injury. Record
degree, if possible.
As nymphs appear, count the number per 10-25 plants/plot or, if the
populations are high, take single leaf samples.
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Record the number of scmash bugs around 10-25 plants/plot in the fall.
Check fruit for injury.
Take yield of marketable and non-marketable fruit, recording number, weight,
and injured and malformed fruit. Records may be taken from the entire plot or
representative section thereform.
Squash Vine Borer, Melittia cucurbitae (Harris)
Control of the squash vine borer, Melittia oucwc'bitae (Harris), must be of
a preventive nature as the borers work inside the stems and vines. Make 4 or
more weekly applications beginning about the time the vines begin to run (about
4 weeks after planting for bush varieties). Carruth and Howe (1948) have shown
a difference in varietal susceptibility to squash vine borers; insofar as
possible choose a more susceptible variety.
Sampling:—Look for wilted plants or masses of coarse excrement, especially
on the stem near the ground level, which the borer has pushed out of the plant.
Count the number of wilted plants/10-25 examined.
Check 10-25 plants for borer tunnels. Record the number of tunnels and
dissect for total larval counts. Carruth and Howe (1948) counted all plants in
a given treatment and determined the percent infested with borers.
Take yield records. Record total number of fruits harvested and average
number and weight of fruit/plant. Records may be taken from the entire plot or
representative section therefrom.
Pickleworm, Diaphania nitidalis (Stoll) and Melonworm, Diaphania hyalinata
(Linnaeus)
These insects are similar and can be evaluated by essentially the same
techniques. There are some differences, however.
Fruits of muskmelon, cucumber and squash are severely injured by the
pickleworm, Diaphania nitidalis (Stoll), watermelon rarely and pumpkin not at
all. Earlier in the season the stems, terminal buds and blossoms are
attacked. The melonworm, Diaphania hyalinata (Linnaeus), on the other hand,
rarely enters the vine or leaf petioles but feeds extensively on the leaves.
Unlike the pickleworm, the melonworm attacks pumpkin.
Brett and Sullivan (1970) have found considerable variation in the
relative susceptibility of cucurbit varieties to pickleworm injurv. When
choosing a test variety, try to select one that is favored by pickleworms.
Unless foliage injury is severe, treat about 1 week before fruit set and
make weekly applications thereafter.
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Sampling:—Counts of infested fruit are reliable (Canerday 1967). Check
10-25 fruit or more/plot and record the number infested. If time permits,
dissect for actual worm count. Frequent checks may be necessary since infested
fruit will rot and disappear in short order.
Familiarize yourself thoroughly with the different types of foliage
injury and record in as many ways as possible: infested stems, terminal buds
or blossoms/10-25 plants/plot in the case of the pickleworm. Check foliage
of 10-25 plants/plot for melonworms.
Take yields. Count damaged and undamaged fruit: record the weight of
marketable fruit and average weight. Records may be taken from the entire plot
or representative section therefrom.
Melon Aphid (Aphis gossypii Glover)
Symptoms in the field first appear as the edges of cucurbit leaves begin
to curl downward with some of them wilted, shriveled, and brown. Like other
species of aphids, the melon aphid, Aphis gossypii Glover, sucks the sap from
the plants causing reduced yields of poor quality. They also transmit cucumber
mosaic virus.
In most test areas, aphids appear in conjunction with tests aimed at other
insects. Occasionally, however, control investigations are started after an
aphid outbreak or as a matter of routine infestation.
Sampling:—Make direct counts of total number of aphids/10-25 leaves/plot,
selected from different plants.
Evaluate plant condition through a foliage or tip injury rating code.
Take yields. Record number and average size of fruit. If some fruit
is unmarketable, determine the number and percent. Records may be taken from
the entire plot or representative section therefrom.
Cabbage Looper (Triahoplusia ni (Hubner))
This cabbage looper, Triohoplusia ni (Hubner), has expanded its host range
to a remarkable extent in recent years, especially in the middle Atlantic and
southeastern states. Cucurbits, cucumbers in particular, have been hard hit and
the looper is now regarded as a major pest of these crops in Virginia and border-
ing states.
Published references concerning looper control on cucurbits appear to be
virtually non-existent. However, the same record taking techniques listed under
the Crucifers are generally applicable for this group also.
Sampling:—After each application, evaluate the results by selecting 10-25
plants or leaves/plot (dependent on the infestation level) and count all the
loopers. Divide loopers into size classifications similar to that used by Hale
and Shorey (1972).
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Take yield records. Records may be taken from the entire plot or represen-
tative section therefrom.
Mites (Tetranuchus sppj
In hot, dry years several species of mites that occur in different regions
often cause rather severe injury to cucurbits. Injury takes the form of a
yellowish, chlorotic effect on the leaves and results in greatly reduced vigor
and yield. As in the case of the cabbage looper, there seems to be little in
the way of published references concerning mite control on cucurbits.
Sampling:—Make direct counts on the number of mites per 10-25 leaves/plot.
If populations are too high, excise 3.22 cm2 (0.5 in. ) or 6.44 cm2 (1.0 in.2)
leaf samples and count the mites thereon. These may be supplemented with
visual ratings of plant vigor.
Take yields, record the total number and average weight of marketable
and unmarketable fruit. Records may be taken from the entire plot or representa-
tive section therefrom.
References
Brett, Charles H. , and Michael J. Sullivan. 1970. The use of resistant varieties
for control of insects on cucurbits in North Carolina. N.C. State Agria. Exp.
Sta. Bull. 440, 25 pages.
Canerday, T. Don. 1967. Control of the pickleworm on cucurbits. J. Econ.
Entomol. 60(6):1705-1708.
Carruth, L.A., and W.L. Howe. 1948. Factors affecting use and phytotoxicitv of
DDT and other insecticides for squash borer control. J. Econ. Entomol.
41(3):352-355.
Fisher, G.T., and R. Green. 1965. Sauash bug control on field pumpkin. Proc.
N. Central BY. ESA 20:123-124.
Gould, George E. 1969. Cucumber beetle control on cucurbit crops. Proc. N.
Central BY. ESA 24(2):119-124.
Hale, R.L., and H.H. Shorey. 1972. Cabbage looper control on cole crops in
southern California: Granular insecticides in the soil indicate lack of
promise. J. Econ. Entomol. 65(6):1658-1661.
Hofmaster, R.N., and R.L. Waterfield. 1972. Insecticide control of the potato
tuberworm in late crop potato foliage. Am. Potato J. ^9:383-390.
Roberts, J.E. , and L.E. Anderson. 1960. Pickleworm control and residue studies
with malathion and Phosdrin. J. Econ. Entomol. 53(3):482-483.
Staples, Robert, Mansoor Ahmad, Sadia Chawdhry, and Gabriel Diaz. 1967.
Effectiveness of several insecticides in controlling cucumber beetles in
eastern Nebraska. J. Econ. Entomol. 60(2):463-466.
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Waites, R.E., and D.H. Habeck. 1968. Evaluation of insecticides for control
of the pickleworm on summer scmash. J. Econ. Entomol. 61(4):1097-1099.
IRISH POTATOES
Irish potatoes, Solanwn tuberosum, are one of the basic food crops in the
world. In addition, they support a wide variety of insect pests, some of which
occur in all areas where potatoes are produced.
Colorado Potato Beetle, Leptinotarsa decemlineata (Say)
The Colorado potato beetle, Leptinotarsa deoemlineata (Say), is well known
to practically everyone. After almost having been eliminated as a potato pest
during the 1950's, this native species has increased to such an extent that it
is the limiting factor in Irish potato production in New York, Virginia and
other eastern and southeastern states. Due to its importance, in this outline
we will emphasize suggested practices for this pest, with the view in mind that
other insects and injury may be sampled and recorded using the same basic test
structures. Both foliage sprays and systemic granulars applied to the soil
should be evaluated.
Crop and Location of Tests:—Select a variety or varieties of Irish
potatoes commonly grown in the area in question. Since some potato varieties
respond differently to insecticidal treatments, especially the soil systemics
(Getzin and Chapman 1959, Hoyman 1969, Libby 1971), it is highly desirable
to observe as many varieties as possible. A uniform soil for the test area is
desirable since the degree of control of plant response may vary in different
soil types.
Experimental Design:—
Ground Application-A randomized complete-block design with three or more
replications per treatment is suggested. Ideally, candidate insecticide per-
formance should be compared with untreated plots and one or more standard
insecticides recommended for the area in question. However, if it is impossible
to have untreated controls, it should be sufficient to compare the treatments
with one or more recommended standards.
Plot size may vary greatly, depending on the uniformity of infestation
and population density. Hofmaster and Waterfield (1972a) obtained good results
with plots 3, 5, or 10 rows wide by 10.7 m (35 ft.) long with 3-5 untreated
rows between plots. Subsequent unpublished investigations by these workers have
shown that 3 row plots, 10.7 m (35 ft.) long with 1 or 2 untreated rows between
plots are about the smallest units that should be used for evaluation of soil
systemics. For "screening" purposes utilizing foliage sprays, single 7.6 m
(25 ft.) long plots with adjacent untreated rows have shown to advantage.
However, as the compounds are taken beyond the screening stage, a 3, 4, 5, or
10 row plot size is recommended. Shands et al. (1972) employed 4 rows 7.6m
(25 ft.) long, Pond (1967) - 4 rows 11 m (36 ft.) long, Powell and Mondor (1973)
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4 rows 30.5 m (100 ft.) long while Bacon et al. (1973) utilized plots 36 rows
wide x 30.5 m (100 ft.) long.
Aerial Application-A minimum of 2 and preferably 3 swaths each 12.2 m
(40 ft. wide) or covering a comparable area is suggested to prevent drift and
have sufficient area in the middle of the plot to collect representative
samples. The length should be sufficient to enable the pilot to fly level and
safely over the plots for at least 182.6 m (600 ft.).
Application and Equipment:—Both spray and granular applications should be
utilized in investigating Irish potato insect control and can be adapted to
most of the species concerned.
o
Ground Application-Knapsack sprayers operating at 2.1 - 4.2 kg/cm
(30-60 psi) and delivering, 187.1-935.4 liters/ha (20-100 gallons of water/
acre) will give satisfactory results. Calibrate the sprayers carefully and
apply tne spray along each side of the row and over the top. Where single
nozzles are used this will require a trip along each side and back over the top.
Backpack sprayers may have a spray boom equipped with 3 nozzles per row.
These nozzles should be adjusted so as to cover the top and sides of each row
(Hofmaster and Waterfield 1972b).
In moving to larger plots a wide variety of pressures and rates are
encountered, e.g., Powell and Mondor (1973) with 187.1 liters/ha (20 gallons/
acre) at low pressure and Pond (1967) 935.4-1169.2 liters/ha (100-125 gallons/
acre) at 28.1 kg/cm^ (400 psi). Insofar as possible, all testing on larger
plots should be with eouipment that is adaptable to the area in question.
Granules may best be applied with a commercial granular applicator attached
to the potato planter. Calibrate the applicator for each formulation and
rate and then plant the potatoes directly without resetting. Many methods of
granule placement are possible. Hofmaster and Waterfield (1972a) studied 8
different methods and concluded that placing the granules directly in the
fertilizer band on both sides of the row gave best results. If the fertilizer
will be broadcast, place the granules about 10 cm (4 in.) from the seed-piece
and about 2.54 cm (1 in.) below the seed-piece level. Some areas such as New
York favor placing the granules directly in the furrow so this method should
be compared to banding.
Aerial Application-Use nozzle arrangement and volume of finished spray
determined to be practical under existing conditions. In most areas the spray
volume will range from 18.7-93.5 liters/ha (2-10 gallons/acre) although good
insect control has been obtained with lower or higher dosages.
Regardless of the method of application, the eauipment should be thoroughly
cleaned before each use. When changing treatments, the tank, boom and nozzles
should be rinsed with water run through the entire system until it is clear.
If more than one rate (kg/ha or Ibs/acre) of toxicant is used, start the
test sequences with the lowest rate, thereby keeping the chances of contamination
at a minimum. Generally, several rates should be applied when testing is in the
initial phase. After the rate or rate range is established and testing is
in the final stages, emphasis should be placed on the probable rate or rates
to be used.
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Sampling:—Direct counts of Colorado potato beetle egg masses and larvae
with supporting measurements of adult foliage injury, either by estimates of
defoliation or the actual number of plants defoliated, give a comprehensive
picture of performance against this pest (Hofmaster and Waterfield 1972a).
Early adult feeding to differentiate effectiveness of soil systemics- Some
systemics become active 7-10 days after plants emerge while others are effective
almost at time of emergence.
1. Number of plants "stemmed" (clipped at ground level by adults feeding)
5-7 days after plant emergence.
2. Number of plants with noticeable foliage injury. Rating of degree
thereof, if feasible.
3. Number of egg masses/10 plants may give some interesting supporting
data.
Effectiveness against potato beetle larvae-
1. Number of larvae/10-25 plants or more. Indicate approximate larval
instars. Record data at definite intervals such as 5, 2.4, 48, and 72 hours
and 7 and 14 days in order to get idea of knockdown and residual. The intervals
selected may be at the discretion of the observer; depending on time available
and need for additional data.
If populations are low, plants can be artificially infested with known
numbers of larvae from the same general area.
2. Some insecticides are slow in action and treated larvae may enter the
soil before dying. Count adult emergence holes/10 samples of 0.093 sq. meters
(1 sq. ft.).
Effectiveness against spring generation adults-
1. Recently emerged adults move about too much for direct counts, unless the
plots are quite large. Numerical foliage injury ratings such as 1 to 5 (Hofmaster
and Waterfield 1972) may be used to advantage.
Take tuber yields and specific gravities . Evaluate potatoes according to
U.S. #1 and U.S. #2 grades. Check on unusual effects of chemicals such as
sprouting, knobs, etc. Yields may be from entire plots or representative sections
therefrom: convert to kg/ha or cwt/acre.
Analysis and Reporting of Data:—Compare treatment means using a valid
statistical method such as Duncan's multiple-range test. Candidate insecticide
performance should be compared with replicated untreated plots and one or more
standard insecticides recommended for the area in question. Where it is
impossible to leave untreated areas, comparison with one or more standard
insecticides should suffice.
The following data should be reported:
1. Pre-test counts to determine approximate level of the insect population
prior to treatment. This may not be possible for all types of insects.
2. Insecticide formulation used and kilograms active toxicant/hectare or
Ibs. active/acre. Describe application equipment, quantity delivered, pressure,
etc.
3. Insect populations on given date, stage of plant growth, and listing
of sampling technique.
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Plant height, stage, and condition at time of treatment and sampling.
5. Temperature, humidity, rainfall and general weather conditions at
treatment. Record these for all applications and all except humidity for the
sampling dates. Overall weather records for the entire test period may be
useful.
6. Percent organic matter and type of soil.
7. Plant response, phytotoxicity or obvious defects in the harvested crop.
Potato Flea Beetle, Epitrix cuaimeris (Harris)
Follow the same general experimental technique as described for the
Colorado potato beetle. The only variations will be in sampling.
Sampling:—Potato flea beetles, Epitrix cucwneris (Harris) move around
so much that sampling them is difficult. Sweeping is not reliable due to
variations in technique and nature of the potato plant.
Count the feeding scars on five leaves/plant, two low down, two near the
middle and one from the top of five or more plants selected at random from each
plot. If the numbers are too large to count, excise definite areas such as
3.22 cm (0.5 in. ) or 6.44 cm^ (1.0 in.2) with a cork borer or other suitable
means and count the scars thereon. (Hofmaster et al. 1967.)
In some areas, two meaningful foliage injury counts may be taken; over-
wintered beetles, and first brood adults. In Virginia these would be approxi-
mately 5-6 weeks apart. Start insecticide applications in both cases as soon as
the beetles appear.
Flea beetle larvae work into the soil and feed on rootlets and tubers.
Injury to the tubers consists of small holes with corky slivers or elongated
winding scars. Count the number of scars on at least 20 tubers or section
thereof, if the injury is heavy. (Hofmaster et al. 1967.)
Take tuber yields and specific gravities. Yields may be from the entire
plot or representative areas therefrom; convert to kg/ha or 100 cwt/acre.
Evaluate according to U.S. #1 or U.S. #2 grades.
Potato Leafhopper, Empoasca fabae Harris, and Other Leafhoppers
Follow the same general technique as for the Colorado potato beetle.
The only variations will be in sampling.
Sampling:—
Adults-Check for presence of adult leafhoppers by sweeping but do not make
counts this way. The adults are so agile that attempts to count them accurately
are not generally practical.
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Nymphs-
1. Apply regular treatment schedule and evaluate by counting the nymphs
on the underside of the leaves (Hofmaster et al. 1967). Select at least 50
leaves/plot.
2. Make visual numerical ratings for development of "hopperburn" injury
by the potato leafhopper, Empoasoa fabae Harris, and southern garden leafhopper,
Empoasca solana DeLong, also the speckled white-stippled appearance by the
western potato leafhopper, Empoasca dbrupta DeLong. Record the extent of purple-
top wilt infection by the aster leafhopper, MacTosteles fascifrons (Stal) and of
curly top virus infection by the beet leafhopper, Circulifer tenellus (Baker).
Count the number of injured or infected plants/given unit or plot and
possibly grade injuries such as "hopperburn", purple-top wilt, etc. Check while
plants are actively growing at blossom time.
Observe the tubers for obvious disease. (If facilities are available, it
might be desirable to store seed and check for disease development when planted
later, either in the greenhouse or field.)
Take yields and specific gravities' yields may be from the entire plot or
representative sections therefrom; convert to kg/ha or cwt/acre. Evaluate
according to U.S. #1 or U.S. #2 grades.
European Corn Borer, OstTJnia nubi-lalis (Hubner)
Irish potatoes are the principal spring host plant of the European corn
borer in Virginia and other Atlantic seaboard states. In addition, the fall
crop is also attacked.
Foliage treatments must be preventive by nature. Two criteria may be used
for initiating the spray program: 1) Consistent moth flights as determined by
light trap collections; and 2) Appearance of egg masses in the field. Successful
tests against this pest require a thorough knowledge of the life history and
cultural practices in the area in question. Applications should be on an approxi-
mate 7 day schedule, and must be started before the borers have entered the plants,
Soil systemics should also be evaluated, especially new chemicals. These
must be applied at planting.
Sampling:—Corn borer infestations are self evident as the plants either
break over or wilt and die. Usually only one field count will be necessary but
this will entail dissection of at least 5 plants/plot - preferably 10 or more
plants.
Insect data may be taken in several forms: 1) Number of plants injured
by corn borers; or 2) Number of borers/plant or plants. (Hofmaster et al. 1967.)
Supporting data should consist of yields and specific gravities. Evaluate
as U.S. #1 or U.S. #2 grade. Yields may be taken from entire plots or represen-
tative sections therefrom; convert to kg/ha or cwt/acre. Note possible secondary
effects from corn borers on the tubers, such as stem-end discoloration, reduced
size, etc.
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Potato Psyllid^ Pavatrioza cockerelli (Sulc)
These small insects are often called jumping plant lice and are problems in
the western states. The feeding of potato psyllid nymphs causes a disease known
as psyllid yellows. This is characterized by a change in color from green to light
yellow and upward curling of the leaves over the midrib. In advanced stages the
plant appears to consist principally of primary stems. The set of tubers is
substantially increased but they never reach marketable size; aerial tubers also
form in the leaf axils.
Sampling:—Start treatments when one or more adult psyllids can be caught
in 100 sweeps of a standard sweep net, with the net opening hitting 2/3 below the
top of the plants (one adult psyllid/100 sweeps may reduce yields as much as 10
bushels per acre). If the psyllid populations are not determined, start
insecticide applications when the plants are 6 inches tall (U.S. Agric.
Handbook 264: Potato Insects: Their Biology and Control, pages 40-41).
Make counts of the'number of psyllid nymphs on at least 25 leaves/plot.
(Gerhardt 1966.)
Check for development of psyllid yellows. Record the number of plants
obviously infected and group in an acceptable rating class to differentiate the
degree of injury.
Take yields and specific gravities. Grade potatoes carefully into U.S.
#1 and U.S. #2 classes: check size average. Yields may be taken from entire
plot or representative sections therefrom, convert to kg/ha or cwt/acre.
References
Bacon, O.G., N.F. McCalley, W.D. Riley, and R.H. James. 1972. Insecticides
for control of potato tuberworm and green peach aphid on potatoes in
California. Am. Potato J. 49:291-295.
Gerhardt, Paul D. 1966. Potato psyllid and green peach aphid control on
Kennebec potatoes with Temik and other insecticides. J. Econ. Entomol.
59(1):9-11.
Getzin, L.W., and R.K. Chapman. 1959. Effect of soils upon the uptake of systemic
insecticides by plants. J. Econ. Entomol. 52(6):1160-1165.
Hofmaster, R.N.^and R.L. Waterfield. 1972a. Insecticides applied to the soil
for the control of the Colorado potato beetle in Virginia. J. Econ.
Entomol. 65(6):1672-1679.
Hofmaster, R.N., and R.L. Waterfield. 1972b. Insecticide control of the potato
tuberworm in late crop potato foliage. Am. Potato J. 49:383-390.
Hofmaster, R.N., R.L. Waterfield, and J.C. Boyd. 1967. Insecticides applied
to the soil for the control of eight species of insects on Irish potatoes
in Virginia. J. Econ. Entomol. 60(5):1311-1318.
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Hoyman, W.G. 1969. Injury of potato foliage by systemic insecticides. Am.
Potato J. 46:182-183.
Libby, J.L. 1971. Phytotoxic effects of soil applied systemic insecticides on
Norland variety potatoes. Proc. N. Central. Br. ESA 26:99.
Pond, D.D. 1967. Field evaluation of insecticides for the control of aphids
on potatoes. J. Econ. Entomol. 60(5):1203-1205.
Powell, Bonnie, M., and T.W. Mondor. 1973. Control of the green peach aphid
and suppression of leaf roll on potatoes by systemic soil insecticides and
multiple foliar sprays. J. Econ. Entomol. 66(1):170-177.
Shands, W.W., and Geddes W. Simpson. 1972. Spraying potatoes to prevent
leafroll spread by the green peach aphid. Am. Potato J. 49:23-34.
The following test methodology to determine the efficacy of insecticides
to control aphids on potatoes is very similar to the method previously described
under Cruciferae and Head Lettuce - Aphids and Thrips. Only the modifications
of that method are noted below.
Crop and Location of Tests:—See also Aphids and Thrips - Cruciferae and
Head Lettuce.
In the early stages of testing,plots 3 beds wide by 7.6 m (25 ft.) long
should be large enough if the counts are made from the middle row of each plot.
Sampling:—Count the total number of apterous aphids on 50-75 leaves per
plot. The number of leaves selected would depend upon the intensity of the
infestation. It is suggested that the leaves be selected at random from the
middle area of the plot. Care should be taken to keep within a well buffered
zone.
Small screening hand plots that are 3 beds wide by 7.6 m (25 ft.) should
have an observation area one bed wide and 1.5 m (5 ft.) from the end of each
plot. This method would provide a 2 bed buffer zone on each side of each plot.
Ground plots that are 12-16 beds wide by 18.3 m (60 ft.) long should have
an observation area 4-6 beds wide and at least 4.6 m (15 ft.) away from the end
of each plot. This method would provide an 8-10 bed buffer zone on each side of
each plot.
Air plots that are 36.6 m (120 ft.) wide by 182.9 m (600 ft.) long should
have an observation area 12.2 m (40 ft.) wide and 30.5-45.7 m (100-150 ft.)
away from the end of each plot. This method would provide a 24.4 m (80 ft.)
buffer zone on each side of each plot.
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References
Bacon, O.G., N.F. McCalley, W.D. Riley, and R.H. James. 1972. Insecticides
for control of potato tuberworm and green peach aphid on potatoes in
California. Am. Potato J. 49:291-295.
Gerhardt, Paul D. 1966. Green peach aphid control on Kennebec potatoes with
Temik and other insecticides. J. Econ. Entomol. 59(1):9-11.
Hale, R.L. 1967-1973. Annual reports on file with the Entomology Department,
University of California, Riverside, California.
Pond, D.D. 1967. Field evaluation of aphicides for the control of aphids on
potatoes. J. Econ. Entomol. 60(5):1203-1205.
Potato Tuberworm, Gnorimoschema operculella (Zeller)
The following test methodology to determine the efficacy of insecticides
to control potato tuberworms is very similar to the method previously described
under Cruciferae and Head Lettuce - Aphids and Thrips. Only the modifications
of that method are noted below.
Crop and Location of Tests:—In the early stages of pesticide testing,
small plots with ground applications would suffice to demonstrate efficacy if
the width and length of the plots were large enough to prevent drift of applied
materials to adjacent plots: and large enough to sample tubers without irift
from adjoining plots influencing the sampling area.
For the very early tests that involve "screening" only, plots can be 3
beds wide by 7.6 m (25 ft.) long. However, as the compounds are tested past
the initial screening stage, larger plots are recommended. Plots 12-18 beds
wide by 18.3 m (60 ft.) long should be large enough to prevent the normal
movement of adult moths from unduly influencing the results between plots under
normal tuberworm pressure.
In the final stages of pesticide development the plot size should be larger
to more closely resemble the commercial ground and air applications. But in any
event should be large enough to prevent drift from adjacent plots from influencing
the results. Since most commercial ground applicators treat 6-8 beds per swath,
plots should be 18-24 beds wide by 60.9 m (200 ft.) long. The length to be
long enough to harvest a representative sample of tubers. Air plots should
be 36.6 m (120 ft.) wide or" 3 swaths of 12.2 m (40 ft.) in width to prevent drift
and to have enough area in the middle of the plot to harvest a representative
sample of tubers. The length to be long enough to enable the pilot to fly
level and safely over the plots for at least 182.9 m (600 ft.).
Application and Equipment:—A broadcast boom with flat fan tips (8004
is suggested) arranged equidistant should provide optimum coverage when using
ground equipment. When small screening tests are applied, knapsack sprayers
operating at 2.1-4.2 kg/cm2 (30-60 psi) will give satisfactory results. The
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boom should have 3- flat fan nozzels per row. Air application equipment
should be commercially acceptable.
The finished spray volume per acre would be dependent on the size of the
potato plants. When foliar spray is applied by small hand or large ground
equipment, 227.1-378.5 liters/ha (60-100 gallons/acre) will give satisfactory
results. When foliar spray is applied by air, 37.9-56.8 liters/ha (10-15
gallons/acre) will give satisfactory results.
The time of application should be when the rows start to close (leaves
from adjoining beds touching across furrow). (Note: there is testing
presently being conducted to ascertain whether earlier pesticide applications
are feasible when '"Monitoring" traps show moth activity.)
Since the control of tuberworms recmire preventive type treatments,
the spray should be applied every 10-14 days until harvest, making sure to
observe the waiting period from the last application to the harvest when
using registered standard materials. The number of days interval is dependent
on the area in which the testing is being conducted. When feasible more than
one time interval between treatments should be evaluated.
Sampling:—Normal harvest procedures for the area in which the test is
being conducted should be followed.
Select harvested tubers at random over a wide area of the plot so that a
representative sample can be taken, but at all times keeping within a well
buffered zone.
Small screening hand plots that are three beds wide by 7.6 m (25 ft.)
long should have a tuber selection area one bed wide and 1.5 m (5 ft.) from
the end of each plot. This method would provide a 2 bed buffer zone on each
side of each plot.
Ground plots that are 12-24 beds wide by 18.3 m-60.9 m (60-200 ft.) long
should have a tuber selection area 4-8 beds wide (middle one-third) and at
least 4.6 m (15 ft.) away from the end of each plot. This method would provide
a 8-16 bed buffer zone on each side of each plot.
Air plots that are 36.6 m (120 ft.) wide by 182.9 m (600 ft.) long should
have a tufeer selection area 12.2 m (40 ft.) wide (middle one-third) and 30.5-
45.7 m (100-150 ft.) away from the end of each plot. This method would provide
a 24.4 m (80 ft.) buffer zone on each side of each plot.
The total number of tubers selected for examination per each pesticide
tested, regardless of the total number of plots, should be 500-600 tubers.
This would give a wider range of selectivity and provide a better reading of
the tuberworm damage.
Each tuber should be examined and recorded as damaged if a tuberworm mine
is found. Extreme care should be taken to be sure that the mine is made by
the tuberworm. Normally one mine is enough to grade the tuber down or
discard it as a "cull", so normally the number of mines per tuber are not
significant enough to record unless "severity of infestation" type data is
requested.
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The total number of tubers infested is recorded as well as tbe percent
tubers infested. Care should also be taken to separate "Green tubers" (those
that are exposed or on the surface) from the "Marketable" tubers when recording
those that are infested.
References
Bacon, O.G., N.7. McCalley, W.D. Riley, and R.H. James. 1972. Insecticides
for control of potato tuberworm and green peach aphid on potatoes in
California. Am. Potato J. 49:291-295.
Hale, R.L. 1967-1973. Annual reports on file with the Entomology Department,
University of California, Riverside, California.
Hale, R.L. 1973-1974. Unpublished data.
Hofmaster, R.N., and R.L. Waterfield. 1972. Insecticide control of the potato
tuberworm in late crop potato foliage. ,4777. Potato J. 49:383-390.
Shorey, H.H. , A.S. Deal, P.L. Hale, and. M.J. Snyder. 1967. Control of potato
tuberworms with phosphamidon in Southern California. J. Econ. Entomol.
60(3):892-893.
LETTUCE
European Lettuce Root Aphid, Pemphigus bursarius (L.)
The following test methodology to determine the efficacy of insecticides
to control European lettuce root aphids on lettuce is very similar to the
method previously described under Cruciferae and Head Lettuce - Aphids and
Thrips. Only the modifications of that method are noted below.
Crop and Location of Tests:—See also Aphids and Thrips - Cruciferae and
Head Lettuce.
For the very early tests that involve "screening" only, plots can be 2
beds (4 rows) wide by 7.6 m (25 ft.) long. However, as the compounds are
tested past the initial screening stage, larger plots are recommended. Plots
4 beds (8 rows) wide by 15.2 m (50 ft.) long should be large enough to provide
adequate space in the treated area.
In the final stages of pesticide development the plot size should be
larger to more closely resemble the commercial ground applications, but in
any event should be large enough to prevent drift from adjacent plots from
influencing the results. Since most commercial ground applicators treat 6-8
beds per swath, plots should be 6-8 beds wide by 30.5 m (100 ft.) long. The
length to be long enough to be able to randomly select and sample lettuce
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root systems to determine the degree of infestation and extent of damage to
the plants.
Application and Equipment:—If granular materials are used, then the
hoppers, tubes and shoes or shanks should be emptied and inspected to see that
no material clings or plugs any part of the equipment.
A broadcast boom with flat fan tips (8004 is suggested) arranged equidistant
should provide optimum coverage when using ground equipment. For a granular
application, equipment that meters out small amounts such as the Gandy,
Gustafeson, etc., and is capable of dispensing the correct amounts to be applied
through shanks should be used.
The time of application should be just before the first irrigation following
thinning of the lettuce.
One application of spray (broadcast) or granular application should be
sufficient if the material has capabilities of controlling the lettuce root
aphid. Granular applications tend to provide more effective and longer control.
For additional information, see Aphids and Thrips - Cruciferae and Head
Lettuce.
Sampling:—Normal harvest procedures for the area in which the test is being
conducted should be followed.
Select lettuce plants to be inspected at random over a wide area of the plot
so that a representative sample can be taken, but at all times keeping within a
well buffered zone.
Small screening hand plots that are 2 beds (4 rows) wide by 7.6 m (25 ft.)
long should have a plant selection area from the middle two rows (inside row of
each bed), and 1.5 m (5 ft.) from the end of each plot.
Ground plots that are 4-8 beds (8-16 rows) by 15.2-30.5 m (50-100 ft.) should
have a plant selection area from the middle rows and 4.6 m (15 ft.) from the end
of each plot.
The total number of lettuce plants inspected for each plot should be at
least 25. If 50 plants can be inspected this would give a wider range of
selectivity and provide a better reading of the lettuce root aphid infestation
and damage.
Each plant should be given a rating for general appearances. The method
is immaterial as long as the rating scale is consistent and is used only to show
any differences in the plant on the surface that may be caused by the root aphid
below the surface.
Each plant should be dug and the root system and surrounding soil area
inspected for presence of the lettuce root aphid.
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To determine the degree of infestation, it is suggested that a count be
taken, for a given period of time (2-3 min.) by 2 or 3 investigators, of the number
of aphids present on roots and in the soil.
Reference
Snyder, M.F. 1975. Personal communication. Farm advisor, Santa Barbara County,
Santa Maria, California.
LIMA BEANS
Lygus Bug, Lygus spp.
The following test methodology to determine the efficacy of insecticides
to control lygus bugs on lima beans is very similar to the method previously
described under Cruciferae and Head Lettuce - Aphids and Thrips. Only the
modifications of that method are noted below.
Crop and Location of Tests:—Small hand plots are not very practical
because of the mobility of the adult lygus bugs. Plots 12-18 beds wide by 18.3 m
(60 ft.) long should be large enough to prevent the normal movement of adult
lygus from unduly influencing the results between plots under normal lygus
pressure.
Since most commercial ground applicators treat 6-8 beds per swath, plots to
test commercial ground applicators should be 18-24 beds wide by 30.5 m (100 ft.)
long. The length must be long enough to harvest a representative sample of bean
pods.
Application and Equipment:—A broadcast boom with flat fan tips (#8002-
8004 is suggested) arranged equidistant should provide optimum coverage when using
ground equipment. Air application equipment should be commercially acceptable.
When foliar spray is applied by ground equipment, a finished spray volume of
227.1-378.5 liters/ha (60-100 gals./acre) will give satisfactory results.
When foliar spray is applied by air, 37.9-56.8 liters/ha (10-15 gals./acre)
will give satisfactory results.
The most critical time for the initial treatment is when the beans are in
the early blossom and bud stage and when the lygus population is 1 nymph or adult
per sweep. This method protects the young blossoms and buds and consequently
increases production of pods. A sweep is one complete pass across one bed (2 rows)
Fifteen sweeps per area is recommended.
The time interval from the initial application to the second treatment is
based on the number of lygus (nymphs and adults) per sweep. This method protects
the developing pods and maturing beans.
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One to three days is suggested as the initial interval between treatment
and observations and then every 7 days thereafter until control is no longer
considered economic.
Sampling:—Count the total number of lygus nymphs and adults from 30 sweeps
per plot. Make the sweeps across one bed (2 rows). One complete pass equals
one sweep. Be sure that the sweeps are made from the middle area of the plot.
To evaluate the effect of lygus control to injury of the mature lima beans,
normal harvest procedures for the area in which the test is being conducted
should be followed.
Select harvested beans at random over a wide area of the plot so that a
representative sample can be taken, but at all times keeping within a well
buffered zone. The beans can be selected directly from the bin on the harvester.
Select approximately 10-20 Ibs. of harvested beans from each plot. From this
sample take 5-10 cups and examine each bean from each cup for lygus injury and
record as damaged. The total number of beans from this sample is counted so that
the percent lygus injury can be recorded.
All beans in a given area of the central part of the plot should be harvested
Marketable beans should be weighed and the data converted to kg yield per
hectare (Ibs. yield per acre).
References
Bushing, R.W., and V.E. Burton. 1974. Partial pest management programs on dry
large lima beans in California: Regulation of L. hesperus. J. Eoon. Entomol.
67(2):259-261.
Hale, R.L. 1967-1973. Annual reports on file with the Entomology Department,
University of California, Riverside, California.
Hale, R.L. 1973-1974. Unpublished data.
McEwen, F.L., and G.E.R. Hervey. 1960. The effect of lygus bug control on the
yield of lima beans. J. Eoon. Entomol. 53(4):513-516.
Sanchez, R.L. 1964. Lygus bug control during flowering in dry lima beans.
Calif. Agric. 18:7.
Shorey, H.H., A.S. Deal, and M.J. Snyder. 1965. Insecticidal control of lygus
bugs and effect on yield and grade of lima beans. J. Eoon. Entomol.
58(1):124-126.
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PEAS
Pea Aphid
The pea aphid, Acyrthosiphon (=Maerosiphum) pisi (Harris), is the most
serious pest of canning and dried peas throughout the pea- and alfalfa-growing
districts of the United States and Canada. Overwintering as eggs or as vivi-
parous females on alfalfa, clovers and other perennial legumes, where it builds
up large colonies in early spring, winged migrants appear on young pea plants
in early May. Reproduction is rapid and colonies develop on terminal shoots
causing leaf distortion and death of the tips. Young pea plants are killed
outright, and yield of older plants is reduced or the quality of peas is affected.
This aphid is also an important vector of pea enation mosaic virus, also of
bean yellow mosaic of peas and alfalfa. Most commercial growers must be prepared
to treat their pea fields and suppress this insect sufficiently to prevent partial
or complete losses of their crop (Metcalf et al. 1962).
Crop and Location of Tests:—Select a variety or varieties of peas commonly
grown in the same geographical area. Locate test plots near alfalfa or other
overwintering hosts for the pea aphid to increase intensity and uniformity of
infestation in peas.
Soil type should be specified if systemics are being tested (Specht and
Chisholm 1970)- Regional or climatic differences may influence efficiency of
the test chemical so test plots should be located in the various regions in
which peas are grown (Kumar and Rabinder 1973).
Experimental Design:—A randomized complete block design with four or more
replicates per treatment is suggested. Plot size may vary greatly depending upon
the anticipated uniformity of infestation and population density, also the type of
equipment and insecticide formulation being used.
In-furrow treatments with systemic insecticides were made in 3- to 6-row
plots that were a minimum 7 m (20 ft.) long (Cook et al. 1963). Systemics in
foliar sprays were applied to peas in rows with compressed air sprayers (Apple
and Martin 1955) . Anderson and Brooks (1947) employed 5-row plots up to 65 m
(200 ft.) long for ground equipment with dusts, sprays, and aerosols; and for
aircraft application their plots were 1 ha (2.47 acres) or larger.
Application and Equipment:—Systemics are applied to the seed before planting
as granules in the furrow with the seed or as sprays to the foliage (Bronson and
Dudley 1951). Dusts and low volume sprays are applied by ground equipment or
aircraft (Anderson and Brooks 1947).
Sampling:—Sampling methods may vary according to the type of experiment
and condition of the crop.
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Cook et al. (1963) estimated the number of living aphids on each of 20-25
randomly located pea plants in each plot and grouped them into 10 categories
from 0 aphids to more than 400.
Anderson and Brooks (1947), and Apple and Martin (1955) sampled populations
by jarring aphids into a pan placed beside the row of plants.
Anderson and Brooks (1947), Davich and Apple (1951), and others used standard
size sweep nets and a prescribed number of strokes for collecting aphids from
plots. The aphids were either counted or measured and the numbers estimated.
Pretreatment samplings should be made. Samples are usually taken 1 day
posttreatment and again 7 and 14 days (Davich and Apple 1951; Bronson and Dudley
1931).
Take yield data including weight and quality of shelled peas, and weight
of vines.
Analysis and Reporting of Data:—Compare treatment means using a valid
statistical method such as Duncan's Multiple Range Test. Candidate insecticide
performance should be compared with replicated untreated plots and one or more
standard insecticides recommended for the area.
The following data should be reported:
1. Make pretreatment counts to determine the approximate level of the
population prior to treatment.
2. Insecticide formulation used and kilograms active ingredient/hectare
(Ibs. a.i./acre). Describe application equipment, quantity delivered, pressure,
etc.
3. Insect populations and stage of development on a given date, listing
sampling technique.
4. Plant height, stage and condition at time of treatment and sampling.
5. Temperature, humidity, rainfall and general weather conditions at
treatment. Record these for all application dates and all except humidity for
the sampling dates. Overall weather records for the entire period may be useful.
6. Percent organic matter and type of soil, also soil temperatures where
systemics are being tested.
7. Plant response, phytotoxicity or obvious defects in the harvested crop.
8. Yield of harvested peas and of vines.
References
Anderson, L.D., and J.W. Brooks. 1947. Pea aphid control in Virginia. J.
Econ. Entomol. 40:199-205.
Apple, J.W., and R. Martin. 1955. Pea aphid control with demeton in relation
to pea plant maturity. J. Eoon. Entomol. 48:193-5.
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Bronson, I.E., and J.E. Dudley, Jr. 1951. Two systemic insecticides for control
ol the pea aphid. J. Econ. Entomol. 44:747-50.
Cook,^W.C., L. Butler, K.C. Walker, and P.E. Featherston. 1963. Granular
in-furrow treatments with phorate and di-syston against the pea aphid on
peas. J. Boon. Entomol. 56:95-98.
Davich, T.B., and J.W. Apple. 1951. Pea aphid control with contact and systemic
insecticidal sprays. J. Econ. Entomol. 44:528-33.
Kumar, R. , and C.C. Burkhardt. 1973. Cyolane and Cytrolane performance against
pea aphids on alfalfa in two climatically different localities. J. Econ.
Entomol. 66:181-2.
Metcalf, C.L., W.P. Flint, and R.L. Metcalf. 1962. Destructive and Useful
Insects, 4th ed. , McGraw-Hill, New York. 1087 pp.
Specht, H.B., and D. Chisholm. 1970. Influence of soil type on the efficacy
of disulfoton and menazon in control of pea aphid on canning peas. J.
Econ. Entomol. 63:1588-9.
Pea Weevil
The pea weevil, Bruchus pisomm (Linne), attacks peas throughout the country.
There is only one generation per year and the winter is passed in the adult stage;
in the south, the adults leave the seeds in the fall and hibernate in protected
places but, in the north, they remain in the seeds that are left in the field or
in untreated seed that is planted. Adults feed on foliage and pollen of pea plants
and lay their eggs on the pods. Hatching larvae bore into the pods and each one
enters a separate seed. Infested green peas at harvest have a dot-line entrance
hole which is generally overlooked and the peas are eaten. This pea weevil never
lays eggs on dry peas, and the adults must get to the growing plants in the spring
or perish without laying eggs.
Crop and Location of Tests:—Since the pea weevil is most serious in the dry
pea or seed growing areas of the intermountain areas, test plots of peas should be
located in Idaho or neighboring states. Also, establish test plots in other areas
where this insect is a serious economic problem, especially where adults come to pea
fields from hibernating quarters.
Experimental Design:—A randomized complete block design with four or more
replicates per treatment is suggested.
Plot size of 0.0405 hectare (0.1 acre) is suggested (Brindley et al. 1948),
but plot size may vary depending upon the anticipated uniformity of infestation
and population density.
The experiment should include an untreated control and one or more standard
treatments for comparison with test compounds.
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Application and Equipment:—Make one application of dust or spray formula-
tions to the foliage of peas during the period of early bloom and before the
adults lay their eggs on the young pods.
Adapt the equipment at hand which is being used for control of pea aphids.
To test systemics against the pea weevil, follow the same procedures as
outlined for tests against pea aphids.
Sampling:—Select 50-100 pea pods at harvest from each plot and observe for
adult emergence from the dry peas in late summer. Samples can be held in screened
containers to allow normal drying and maturity of peas and yet retain emerging
weevils. Since only one weevil develops per pea seed, the effectiveness of test
material is readily determined.
Analysis and Reporting of Data:—See this section under Pea Aphid.
Eeferences
Brindley, T.A., R. Schopp, and F.G. Hinman. 1947. Field tests versus
laboratory tests with DDT against the pea weevil. J, Eoon. Entomol.
41:832-3.
Metcalf, C.L., W.P- Flint, and R.L. Metcalf. 1962. Destructive and Useful
Insects, 4th ed., McGraw-Hill, New York. 1087 pp.
PEPPERS, Capsicum annuum
European Corn Borer, Ostr>in-La nubi~la1i,s (Hubner)
The European corn borer, Ostrinia nub-ilalis (Hubner) , is a limiting factor
in pepper production in the mid-west, mid-Atlantic states and southeastern states.
Detection is especially difficult since the young borers enter the fruit under
the cap and leave little external evidence. Due to its extreme importance in
certain areas, suggested practices for this pest will be emphasized. Other insects
and injury may be sampled and recorded, using essentially these same test methods.
Both foliage sprays and systemic granulars applied to the soil should be evaluated.
Crop and Location of Tests:—Select the variety or varieties commonly grown
in the same geographic area.
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Exgerimental Desipnj_—
Ground Application-A randomized complete block design with three „. ^^
replications per treatment is suggested. Ideally, candidate insecticide perfor-
mance should be compared with one or more standard insecticides recommended for
the area in question. However, if it ±s impossible to have untreated controls,
it should be sufficient to compare the treatments with one or more recommended
standards.
Plot size may vary greatly, depending on the anticipated uniformity of
infestation and population density. Hofmaster et al. (1960) used 3 row plots
15.2 m (50 ft.) long with 2 untreated rows between each plot. Later unpublished
data showed that single 15.2 m (50 ft.) rows with 1 adjacent untreated row gave
consistent results. Tysowsky (1969) obtained good results by treating single
24.4 m (80 ft.) long plots bordered by untreated rows. Burbutis et al. (1960
and 1963) and Ryder et al. (1969) conducted extensive field research on corn
borer on peppers using plots ranging from 4 rows wide x 21.3 m (70 ft.) long to
plots 122 m (400 ft.) long and 20 rows wide. Hale and Shorey (1971) worked with
plots ranging from 6-12 rows wide and 18.3-45.7 m (60-150 ft.) long.
Aerial Application-A minimum of 2 and preferably 3 swaths each 12.2 m
(40 ft.) wide or covering a comparable area is suggested to prevent drift and
to have sufficient area in the middle of the plot to collect representative
samples. The length should be sufficient to enable the pilot to fly level and
safely over the plots for at least 182.6 m (600 ft.).
Application and Equipment:—Both liquid and granular applications should be
considered in investigating pepper insect control and can be adapted to most of
the species concerned.
Ground Application-Due to the nature of the pepper plant and difficulty
in hitting the cap area, problems of coverage can occur with backpack sprayers
although this method may be used to advantage in combating pests other than the
corn borer.
Hofmaster et al. (1960) applied 935.4 liters of water/ha (100 gallons/acre)
at 17.6 kg/cm2 (250 psi) using 5 or 6 nozzles/row. Tysowsky (1969) also used a
power sprayer in small plots, application was at 7.03 kg/cm2 (100 psi) at 467.7
liters/ha (50 gallons/acre). Burbutis et al. (1960 and 1962) and Ryder et al.
(1968) conducted extensive field scale tests with power equipment delivering
467.7-935.4 liters/ha (50-100 gallons/acre) with both high pressure and air
blast sprayers. Hale and Shorey (1971) evaluated application methods against
another pepper pest, the green peach aphid, and found nozzle arrangement to be
important.
Granules are usually side-dressed in the fertilizer band after the peppers
have been transplanted and are established. Commercial applicators may be used
(Ryder et al. 1969) or hand application (Shorey 1963). In Delmarva, two applica-
tions, one at 2-4 weeks after transplanting and another 4-6 weeks later are recom-
mended. Placement will be governed by plant size but 5.1-12.7 cm (2-5 in.) deep
and 7.6-15.2 cm (3-6 in.) from the plant are suggested.
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Aerial Application-Use nozzle arrangement and volume of finished spray
determined to be practical under existing conditions. In most areas the spray
volume will range from 18.7-92.5 liters/ha (2-10 gallons/acre) although good
insect control has been obtained at lower or higher dosages.
Regardless of the method of application, the equipment should be thoroughly
cleaned before each use. When changing treatments, tne tank, boom and nozzles
should be rinsed with water run through the entire system until it is clear.
If more than one rate (kg/ha or Ibs/acre) of toxicant is used, start the
test sequences with the lowest rate, thereby keeping the chances of contamination
at a minimum. Generally, several rates should be applied when testing is in the
initial phase. After the rate or rate range is established and testing is in the
final stages, emphasis should be placed on the rate or rates to be submitted for
registration.
Sampling:—Check and dissect, if necessary, 25-100 mature peppers/plot for
corn borer injury. Be sure to look carefully under the cap area. If larger
samples with uneven numbers are collected, obtain percent infestation and convert
to arc sin ± for analysis. (Burbutis et al. 1960 and 1962, Hofmaster et al.
1960, Rydef et al. 1969). Since many fruits rot if infested with borers, keep a
close check for "rots" and record these. Examine and remove "rots" as they appear.
Take yields, recording the marketable fruit, % loss due to borers and number
of "rots". Yields may be from the entire plot or representative sections there-
from; convert to metric tons/ha or tons/acre.
Analysis and Reporting of Data:—See statement under Cabbage Looper -
Cruciferae. (Obviously, in treatments of a precautionary type (corn borer)
based on a preventive schedule, pre-test counts cannot be taken as such.
However, light trap collections may provide helpful information.)
Green Peach Aphid (#l) Myzus persicae (Sulz.)
Yields may be seriously reduced by aphid feeding and the fruit made unsalable
from a black fungus developing in aphid "honeydew" which dripped on the fruit.
Follow the same general procedures as outlined for corn borers. The only differences
will be in sampling.
Sampling:—Count the total number of aphids/10-100 leaves/plot or parts
thereof, if the infestation is heavy. (Burbutis et al. 1960 and 1962, Hale and
Shorey 1971, Hofmaster et al. 1960, Shorey 1961 and 1963.)
Harvest and record marketable fruit and peppers covered with black "honey-
dew" fungus. Yields may be taken from the entire plot or representative
sections therefrom; convert to metric tons/ha or tons/acre.
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Pepper Maggot^ Zonosemata electa (Say)
^ The larvae of this Tephephritid fly feed entirely inside the pepper fruits.
A single maggot makes the pepper worthless for marketing. This pest is unusual
in that it is single brooded and the larvae pupate in the soil, with adults
emerging the following year (Davidson and Peairs 1966).
Control demands a thorough knowledge of the biology. Check for the
appearance of adults (two-winged, yellow striped flies about 0.76 cm (0.3 in.)
long) and make regular treatments as long as the flies are around. In New
Jersey treatments should start the last week of June and continue at 7 day
intervals until July 15; treat every 10 days thereafter through July. Plots
should be 4 rows wide by 15.2 m (50 ft.) long with at least 4 replications.
Sampling:—Check 50-100 fruit/plot for pepper maggot injury. Race and Reed
of Rutgers University, New Brunswick, New Jersey, suggest the following method of
evaluation (personal communication):
After the 3rd spray application (usually about mid-July in New Jersey)
collect 50 peppers from the center rows of each plot; 25% of the collected
peppers/plot should be the smallest size present in the field, ranging up to
thumbnail size; 25% should be the largest size and the remaining 50% should be
somewhere in between.
Check for egg punctures by examining the outside surfaces of all fruits.
The egg puncture is easy to spot and is usually typified by a small dimple-like
or depressed area. Experience can be gained very quickly in determining those
fruits which have egg punctures and those which do not. Peppers with egg
puncture marks should be opened carefully with a sharp blade. (It is not
necessary to open those peppers which do not show the typical egg puncture
scar.) Look for the tiny eggs on the inside surface of the fruit wall or
presence of maggots feeding on the core. Full grown maggots obtain a length
of approximately 6.4 cm (% inch). Usually not more than 2 or 3 maggots occur
in each pepper and often only one.
Record the number of fruit with egg punctures and total number of punctures.
At the same time obtain the number of fruit infested with maggots and total
number of maggots.
Take yields and estimate loss due to pepper maggot. Yields may be from the
entire plot or representative sections therefrom; convert to metric tons/ha or
tons/acre.
References
Burbutis, P.P-, R.S. VanDenburgh, D.F. Bray, and L.P- Ditman. 1960. European
corn borer control in peppers. J. Soon. Entomol. 53(4):590-592.
Burbutis, P.P., D.J. Fieldhouse, D.F. Grossman, R.S. VanDenburgh, and L.P.
Ditman. 1962. European corn borer, green peach aphid and cabbage looper
control in peppers. J. Soon. Entomol. 55(3):285-288.
Davidson, Ralph Howard, and Leonard Marion Peairs. 1966. Insect Pests of Farm,
Garden and Orchard. John Wiley & Sons, Inc., 675 pages (306-307.)
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Hale, R.L., and H.H. Shorey. 1971. Effect of foliar sprays on the green peach
'aphid on peppers in southern California. J. Boon. Entomol. 64(2):547-549.
Hofmaster, R.N., D.F. Bray, and L.P. Ditman. 1960. Effectiveness of insecticides
against the European corn borer and green peach aphid on peppers. J. Econ.
Entomol. 53(4):624-626.
Ryder, J.C., P.P. Burbutis, and L.P. Kelsey. 1969. Systemic insecticides for
control of European corn borer and green peach aphid on peppers. J. Econ.
Entomol. 62(5):1150-1151.
Shorey, H.H. 1961. Effect of various insecticide treatments on populations of
the green peach aphid on peppers in southern California. J. Boon. Entomol.
54(2):279-282.
Shorey, H.H. 1963. Soil applications of systemic insecticides for control of
green peach aphid on peppers. J. Boon. Entomol. 56(3):340-342.
Tysowsky, Michael Jr. 1969. Insecticide tests for the control of the European
corn borer on peppers. Trans. Peninsula Hortic. Soo. 59:22-25.
Green Peach Aphid (#2) Mysus persicae (Sulz.)
The following test methodology to determine the efficacy of insecticides to
control green peach aphids on peppers (bell or chili) is very similar to the
method previously described under Cruciferae and Head Lettuce - Aphids and Thrips.
Only the modifications of that method are noted below.
Crop and Location of Tests:—In early stages of testing, plots 3 beds wide
by 7.6 m (25 ft.) long should be large enough if the counts are made from the
middle row of each plot.
Since most commercial ground applicators treat 6-8 beds per swath, plots
to test using commercial ground applicators can be 6-8 beds wide by 18.3 m
(60 ft.) long.
Application and Equipment:—When the pepper plants are small enough so that
a ground application can be safely made without knocking an excessive amount of
blossoms and small pods from the plant, a row crop boom should be used for
proper coverage.
Sampling:—Count the total number of apterous aphids on 50-75 leaves per plot
The number of leaves selected would be dependent on the intensity of the infesta-
tion. It is suggested that the leaves be selected at random from the upper one-
third and the lower one-third of the plants. Care should be taken to keep within
a well buffered zone in the middle area on the plot.
Small screening hand plots that are 3 beds wide by 7.6 m (25 ft.) long
should have a leaf selection area one bed wide and 1.5 m (5 ft.) from the end of
each plot. This method would provide a 2 bed buffer zone on each side of each
plot.
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Ground plots that are 6-8 beds wide by 18.3 m (60 ft.) long should have
a leat selection area 2-4 beds wide and at least 4.6 m (15 ft.) away from the
end of each plot. This method would provide a 4 bed buffer zone on each side
of each plot.
Air plots that are 36.6 m (120 ft.) wide by 182.9 m (600 ft.) long should
have a leaf selection area 12.2 m (40 ft.) wide (middle one-third) and 30.5-
45.7 m (100-150 ft.) away from the end of each plot. This method would provide
an 24.4 m (80 ft.) buffer zone on each side of each plot.
References
Burbutis, P.O., D.J. Fieldhouse, D.F. Grossman, R.S. VanDenburgh, and L.P. Ditman.
1962. European corn borer, green peach aphid and cabbage looper control in
peppers. J. Eoon. Entomol. 55(3):285-288.
Hale, R.L., and H.H. Shorey. 1971. Effect of foliar sprays on the green peach
aphid on peppers in Southern California. J. Eoon. Entomol. 64(2):547-549.
Hale, R.L. 1967-1973. Annual reports on file with the Entomology Department,
University of California, Riverside, California.
Hale, R.L. 1973-1974. Unpublished data.
Hofmaster, R.N., D.F. Bray, and L.P. Ditman. 1960. Effectiveness of insecticides
against the European corn borer and green peach aphid on peppers. J. Eaon.
Entomol. 53(4):624-626.
Shorey, H.H. 1963. Soil applications of systemic insecticides for control of
the green peach aphid on peppers. J. Eoon. Entomol. 56(3):340-342.
Shorey, H.H., and R.L. Hale. 1963. Control of green peach aphid on peppers.
Calif. Agric. 17(12):10-11.
SNAP BEANS, LIMA BEANS AND SOUTHERN PEAS
The crops include snap bean - Phaseolus vulgar-is, lima bean - Phaseolus
lunatus, and cowpea or southern pea - Vigna sinensis. These beans are infested
by a large number of insect pests both in the field and in storage.
Mexican Bean Beetle, Epilao'hna varivestis Mulsant
The Mexican bean beetle, Epilaahna varivestis Mulsant, has received more
research efforts and publicity than any other bean pest. Like so many imported
pests, its spread was extremely rapid, especially after moving eastward across
the Mississippi around 1920. Suggested test procedures for this insect will be
emphasized. However, other insects and injury may be sampled and recorded
employing the same or quite similar test methods. Both foliage sprays and systemic
granulars should be evaluated.
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The following test methodology to determine the efficacy of insecticides
to control the Mexican bean beetle on beans is very similar to the method
previously described under Cabbage Looper - Cruciferae. Only the modifications
of that method are noted below.
Experimental Design:—Plot size may vary greatly, depending on the uniformity
of infestation and population density. The following references to plot size are
not limited to Mexican bean beetle investigations but include other bean pests.
Chalfant (1973) employed plots 15.2 m (50 ft.) long by 4-6 rows wide in
southern pea studies in Georgia. Judge et al. (1973) used 2 row 18.3 m (60 ft.)
long plots with 2 buffer rows while Webb et al. (1970) obtained good results with
single 9.1 m (30 ft.) rows. Comments from a number of workers indicated that 3-6
row plots ranging from 9.1 m (30 ft.) to 22.9 m (75 ft.) in length should afford
good test conditions for the entire bean insect complex. Where optimum stress is
desired, single row 9.1 m (30 ft.) to 22.9 m (75 ft.) long plots with 1 or more
buffer rows may be used to advantage.
Application and Equipment:—Specially adapted small plot sprayers such as
the C02 sprayer used by Wolfenbarger and Schuster (1963) are helpful. Mechanized
equipment (Chalfant 1973) in which a tractor drawn sprayer delivering 467.7
liters/ha (50 gallons/acre) at 3.5 kg/cm2 (50 psi) with 3 nozzles/row, can be
used in small plots to simulate field scale conditions.
Granules may be applied with a commercial granular applicator attached to
the planter. Calibrate the applicator for each formulation and rate and then
plant directly without resetting. Webb et al. (1970) used an Alan distributor in
placing the granules 2.54 cm (1.0 inch) below the seeds in the furrow or 5.08 cm
(2.0 inches) to the side of the beans. Judge et al. (1970)distributed the granules
directly over the beans; whereas Fisher (1966) placed the granules in the
fertilizer band. Ideally, the insecticides should be placed approximately 5.1 cm
(2.0 inches) to the side of the beans and at this same depth. Whatever the place-
ment decided upon, be sure to pinpoint the granular location as accurately as
possible. Although many chemicals are phytotoxic when in direct contact with
the seeds, it will be advisable to include a direct contact series.
Sampling:—Make direct counts of larvae, taking samples of 10-25 plants/plot.
If populations are not too heavy, record all larvae on the plant; otherwise
check the larvae on at least 25 leaves/plot. Judge et al. (1970) sampled 15 plants/
plot. The pupae attach themselves directly to the leaves. Occasionally it is
desirable to make pupal counts, providing the initial treatment was applied prior
to pupation. A further check on insecticidal efficiency may be obtained by
determining whether adults emerge from pupae present at the time of treatment.
Activity of the test insecticide against the adults should be determined
by feeding injury ratings.
Take yield records - 2 or 3 harvests. Checks on pod quality and size may
show unexpected differences. Records may be from entire plot or representative
sections therefrom.
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Bean Leaf Beetle, Cerotoma tr-ifuroata (Forster)
Damage by bean leaf beetles, Cerotoma trifurcata (Forster), is two-fold.
The adults feed on the underside of the leaves, eating rounded holes in them,
while the larvae feed underground on the roots and stems, often girdling the
plants.
Sampling:—
Adults-Make direct counts on 10-25 plants/plot. Supplement with counts of
feeding holes/10-25 leaves/plot.
Larvae-Remove plants from the soil and examine roots for larval injury and/
or larvae. Check 5-10 plants/plot at least one time.
Take yields from 2 or 3 harvests, either from the entire plot or represen-
tative sections therefrom.
Bean Aphid, Aphis fabae Scopoli
As is the case with most aphids, continuous feeding by the bean aphid,
Aphis fabae Scopoli, causes the leaves to turn yellow, plants to become dwarfed
and malformed with quality and yield reduced.
Sampling:—Dependent on populations, count all aphids on 10-25 leaves/plot
or representative portions of 3.22 cm (0.5 in.2) or 6.44 cm^ (1.0 in. ) therefrom.
Hagel (1970) found samples of 25 leaflets to be adequate.
Take yields from 2 or 3 harvests and record differences in size and
quality of pods. Records may be from the entire plot or representative sections
therefrom.
Cowpea Curculio, Chaloodermus aeneus Boheman
The curculio larvae feed within the developing seeds of various members of the
bean family but prefer southern peas. Infestation usually occurs in the field
where the female deposits eggs in feeding punctures as the southern peas begin to
form. Pea pods infested with curculio can be recognized by small, brown, wart-
or blister-like spots on the surface. These are either feeding punctures or
areas present which may contain an egg or small grub. Make 3-5 treatments at 4-5
day intervals, beginning at blossoming.
Sampling:—Chalfant (1973) collected 50-100 pods/plot at 5-7 days after the
last treatment. The pods were shelled and feeding and oviposition punctures
(stings) on the green peas recorded. Other workers including Dupre and Beckham
(1955) and Wolfenbarger and Schuster (1963) supplemented the above technique by
collecting 50-100 pods at the developmental stage for processing, placing them
in holding containers fitted in such a manner as to allow the larvae to fall to
the bottom as they matured and left the peas.
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Examine 50-100 pods/plot for stings, feeding punctures and damaged peas.
Record the number of injured and uninjured pods and also the number of damaged
peas and punctures/pod.
Place 50-100 pods/plot in holding cartons and check for larval emergence.
Records should be taken of the total numbei of emerged larvae and damaged peas.
Take yield records and estimate loss due to the curculio. Records may
be from the entire plot or representative sections therefrom.
Leafhoppers
Two species of leafhoppers, the potato leafhopper, Empoasea fabae (Harris),
and beet leafhopper, Ci-TOulifer tenellus (Baker), cause extensive damage to beans.
The potato leafhopper causes dwarfed, crinkled and curled foliage, rosette
formation, or small triangular brown areas at the tips of the leaves, gradually
spreading around the entire margin. Affected plants produce few pods.
The beet leafhopper carries a virus disease known as "curly top" and is
limited to the western areas. Beans in the seedling or crookneck stage are most
susceptible to curly top and usually die when infected. However, plants infected
when they are in a more advanced stage of growth often survive but produce
stunted pods. Curly top is the most important factor limiting the growing of
snap beans for seed in southcentral Idaho where the bulk of the nation's bean
seed is produced. Unlike the potato leafhopper, the beet leafhopper does not
reproduce on bean plants.
Sampling:—Count the number of potato leafhopper nymphs on 10-25 leaves/
plot or, if the infestation is not heavy, on the entire plant. Judge et al.
(1970) found counting all the nymphs on 15 plants to be practical. Supplement
these counts with an evaluation of leafhopper damage to the foliage. Record
plants with visible symptoms and grade according to severity.
Count the number of beet leafhopper adults/10-25 plants/plot. To do so will
require a special sampling cage similar to the one developed by Hills (1933) and
widely accepted by entomologists in the curly top areas. Supplement these counts
with an evaluation of curly top damage. Make observations shortly after plant
emergence and record plant stand since young plants may be killed. Check for
stunted and distorted plants.
Make several harvests. Look closely for small, malformed pods and
compare these with the number of apparently normal pods. Records may be taken
from the entire plot or representative sections therefrom.
References
Chalfant, Richard B. 1973. Cowpea curculio: Control in southern Georgia.
J. Econ. Entomol. 66(3):727-729.
Dupre, M., and C.M. Beckham. 1955. The cowpea curculio, a pest of southern peas.
Ga. Agric. Exp. Sta. Bull. N.S. 6, 32 p.
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' • • 1966. Control of the potato leafhopper on canning lima beans using
systemic insecticides. Proc. N. Central Br. ESA 21:120-122.
a^£ ' ' ' 1970. Systemic insecticides and control of insects and mites on
beans, j. Econ. Entomol. 63(5):1486-1489.
Hills, Orin A. 1933. A new method for collecting samples of insect populations.
J. Boon. Entomol. 26(4)-.906-910.
Judge, F.D., F.L. McEwen, and H.B. Rinick, Jr. 1970. Field testing candidate
insecticides on beans and alfalfa for control of Mexican bean beetle,
potato leafhopper and plant bugs in New York state. J. Eoon. Entomol.
63(l):58-62.
Webb, Ralph E., Floyd F. Smith, and A.L. Boswell. 1970. In-furrow applications of
systemic insecticides for control of Mexican bean beetle. J. Econ. Entomol.
63(4):1220-1223.
Wolfenbarger, D.A., and M.F. Schuster. 1963. Insecticides for control of the
cowpea curculio, Chaloodermus aeneus, in southern peas. -J. Eoon. Entomol.
56(6)-.733-736.
SWEET CORN
Corn Earworm, HeUothis zea (Boddie)
The following test methodology to determine the efficacy of insecticides
to control corn earworms on sweet corn is very similar to the method previously
described under CruCiferae and Head Lettuce - Aphids and Thrips. Only the
modifications of that method are noted below.
Crop and Location of Tests:—The plot size should depend on the stage of
pesticide development. In the early stages, small hand applications would
suffice to demonstrate efficacy, either as dusts or sprays. For the very early
tests that involve "screening" only, plots can be 3 rows wide by 15.2 m (50 ft.)
long.
In the final stages of pesticide development the plot size should be larger
to more closely resemble the commercial ground applications. But in any event
should be large enough to prevent drift from adjacent plots from influencing
the results. Plots should be a minimum of 4 rows wide by 60.9 m (200 ft.) long.
Airplane applications are ineffective on moderate to heavy earwonn popula-
tions which occur in most market sweetcorn-producing areas of the middle and
southern parts of the U.S.A.
Application and Equipment:—Preliminary tests can be hand treatments either
as dusts or sprays. Large scale field tests should be made with a high clearance
spray rig, using 2-4 nozzles per row adjusted to cover only the ear area with
particular attention to thorough coverage of the silks.
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Satisfactory results can be obtained by applying a finished spray volume of
113.6-189.3 liters/ha (30-50 gals./acre). A moderately coarse spray with
hollow cone nozzles provides good results.
The time of application should be when the corn ears start to silk. It
should be remembered that the problem is primarily with eggs laid on the silks
and the young larvae hatching from these eggs in 3-5 days.
In view of the fact that the larvae migrate down the silk and soon are
concealed within the silk channel between the husks at the tip of the ear and the
silk grows rapidly, it is necessary to make 3-6 applications at 2-3 day intervals
for adequate control.
Sampling:—Select at random 25-50 ears from the middle row or rows from each
plot. Keep 1.5-3.0 m (5-10 ft.) away from the end of each plot when sampling the
ears. Each ear should be carefully examined for earworm damage and recorded. The
data should be recorded as "percent ears infested".
References
Anderson, L.D. 1975. Personal communication. Entomology Department, University
of California, Riverside, California.
Anderson, L.D., and H. Nakakihara. 1968. Toxicity of pesticides to corn earworm
on sweet corn in Southern California. J. Eoon. Entomol. 61(6):1477-1482.
Fall Armyworm, Spodoptera frugiperda (Smith)
The fall armyworm, Spodoptera fTugiperda (Smith), is often found associated
with corn earworms and will generally be controlled in the sweet corn ear with the
same sprays used against earworms. However, there are some important differences
in habit that make the fall armyworm a special problem at times.
Quite often, especially following cool, wet springs, tremendous fall armyworm
outbreaks occur making crop protection almost impossible. Unlike the earworm,
which lays its eggs singly for the most part, the fall armywofm deposits up to 100
or more eggs in clusters. Then, too, earworms seldom become numerous enough to
seriously damage young sweet corn whereas fall armyworms may completely destroy
a planting within a short time after plant emergence. Brett (1953), working in
North Carolina, has stated that the fall armyworm is the limiting factor in the
production of late sweet corn in that area. The same is true for Virginia.
No attempt will be made to discuss plot size or equipment for treatment once
the silk stage is reached since the techniques for earworm control will be appli-
cable. However, due to the habits of the fall armyworm in feeding deep in the
whorls of the young sweet corn plant, it will be necessary to apply chemicals from
an overhead boom directly above. Harrison et al. (1959) and Reed (1959) were
among the first to recognize the possibility of using granulars on sweet corn.
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-107
In most sweet corn areas it will be necessary to maintain a 2-3 day or
shorter application schedule after silking begins.
Sampling^ — Make direct counts of armyworms or armyworm injury in 10-50 corn
plants (Harris 1961, Janes 1974, Reed 1959). Henderson et al. (1962) point out
the necessity of unrolling the leaves and thoroughly examining the whorls. If
the plants have been rather severely injured prior to treatment, be sure to base
the records on fresh damage. Foliage injury ratings may be useful also.
Count the armyworm infestation in samples of at least 25 ears/plot (Bowman
and Young 1969, Janes 1973). Carefully observe and record the degree of injury
into the same classes as used forearworms.
References
Bowman, M.C., and J.R. Young. 1969. Persistence and degradation of residues of
Ciba C-9491 and their control of fall armyworms and corn earworms. J. Econ.
Entomol. 62(6) :1468-1472.
Brett, Charles H. 1953. Fall armyworm control on late planted sweet corn.
J. Econ. Entomol. 46(4) :714-715.
Harris, Emmett D., Jr. 1961. DDT spray formulations and dosages for control of
corn stem weevil, Hyperodes hum-il-is ., and fall armyworms, Layphgma frugiperda.,
on sweet corn. J. Econ. Entomol. 54(3) :546-549.
Harrison, Floyd P., Roderick M. Coan, and L.P. Ditman. 1959. Experiments on
control of fall armyworm in sweet corn. J. Econ. Entomol. 52(5) :838-840.
Henderson, C.F., H.G. Kinzer, and J.H. Hatchett. 1962. Insecticidal field
screening tests against the fall armyworm in sorghum and corn. J. Econ.
Entomol. 55(6) -.1005-1006.
Janes, M.J. 1973. Corn earworm and fall armyworm occurrence and control in
sweet corn ears in Florida. J. Econ. Entomol. 66(4) :973-974.
Janes, M.J. 1974. Foam application of methomyl to sweet corn and leafy
vegetables. J. Econ. Entomol. 67(2) :249-250.
Reed, John P. 1959. The role of granulated insecticides for control of sweet
corn pests in New Jersey. J. Econ. Entomol. 52(5) :972-974 .
Corn Flea Beetle, Chaetocnema pullcai"La Melsheimer
Very little literature is available on the control of the corn flea beetle,
Chaetocnema pulicaria Melsheimer. This pest is important for two reasons:
1) It may completely destroy young corn seedlings by direct feeding; and 2) Over-
wintered beetles carry bacterial wilt (Stewart's disease) within their bodies
and transmit it to the corn plants, where it is picked up by uninfected beetles
who may carry the disease to other healthy corn plants.
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Robert (1955) states that "the growing of resistant varieties is the only
practicable way of controlling bacterial wilt." However, at about this same
time Adams and Chupp (1954) and Luckman (1955) demonstrated that flea beetle
control with insecticides would definitely reduce Stewart's disease in sweet corn.
In determining efficiency of insecticides, plot size need not be large but,
due to the activity of infectious beetles, each plot should be isolated as much
as possible from other treated areas. Henderson et al. (1962) treated 3 row,
15.2 m (50 ft.) long areas but had each plot bordered by up to 6 adjacent untreat-
ed rows.
Sampling:—Count the number of flea beetles on 25-100 sweet corn plants/
plot. Henderson et al. (1962) used a Hills' sampling cage in determining flea
beetle populations (Hills 1933).
Later in the season rate the incidence of bacterial wilt. Be sure to
familiarize yourself with the symptoms as they are described by Robert (1955).
Take yield records, noting number, weight, size and general conformation
of the ear. Measurements as to plant height and observations on general
condition may be helpful.
References
Adams, J. Alfred, and Charles Chupp. 1954. Flea beetle control - a preventive of
Stewart's disease on sweet corn. Farm Res., New York, Geneva Agric. Expt.
Stn. 20(2):8-9.
Henderson, C.F., H.G. Kinzer, J.H. Hatchett, and E.G. Thompson. 1962. Field
insecticide screening tests against the corn flea beetle. J. Boon. Entomol.
55(6):1008-1009.
Hills, Orin A. 1933. A new method for collecting samples of insect populations.
J. Eaon. Entomol. 26(4):906-910.
Luckman, W.H. 1955. A new way of reducing Stewart's disease in sweet corn.
Proc. N. Central Br. ESA 10:79.
Robert, Alice L. 1955. Bacterial Wilt and Stewart's Leaf Blight of Corn.
U.S. Dep. Agric. Farmers Bull. 2092. 13p.
European Corn Borer, Ostrinia nubilalis (Hubner)
The European corn borer, Ostrinia nubilalis (Hubner), is often associated
with corn earworms and generally will be controlled in the sweet corn ear with
the same sprays and schedule used against earworms. There are some important
differences in habit that make the corn borer a special problem in certain areas.
The European corn borer moths, in contrast to the corn earworm adult which
lays its eggs singly for the most part, deposits its eggs in clusters of up to
50 on the undersides of the leaves. The young worms bore into various parts of
the plant, ears included, and often cause the stalks to break and ear section to
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me m contact with the ground. Unless the corn borers are controlled, complete
osses of sweet corn plantings may occur, especially in late summer in the south-
eastern states. Damage to the ears may be especially critical since the borers
o ten feed along the entire length of the ear, rendering it entirely unfit for
marketing or processing.
No attempt will be made to discuss plot size or equipment once the silk
stage is reached since the techniques for earworm control will be applicable.
However, due to the habits of corn borers in feeding deep within the whorls of
the young sweet corn plant, it will be necessary to apply chemicals from an over-
head boom directly above the row. Harrison et al. (1959) and Reed (1959) were
among the first to recognize the possibility of using granulars against sweet
corn pests.
In most sweet corn areas it will be necessary to maintain a 2-3 day applica-
tion schedule after silking begins. Earlier in the season, applications may be
based on light trap collections of moths, the number of egg masses or egg hatch.
Harrison and Press (1971) have reviewed the literature on timing of treatments
for corn borer control and conclude that those who have worked with this phase
have many points of view and have approached the problem from many aspects. From
this it would appear unwise to attempt to establish definite overall guidelines.
Instead check local practices for the area concerned. Pest management groups
working with corn borers should be able to give helpful advice.
Sampling:—Make direct counts of corn borers and borer injury in 25-100
sweet corn plants (Harrison and Press 1971, Hudson 1962 and 1963). Dissect the
plants and record the number of larvae, total number of tunnels and number of
infested plants.
Count the corn borer infestation in samples of 25-100 ears/plot. Carefully
observe and record the degree of injury into the same classes as used for earworms.
Eeferences
Harrison, Floyd P., Roderick M. Coan, and L.P. Ditman. 1959. Experiments on
control of fall armyworm in sweet corn. J. Eoon. Entomol. 52(5):838-840.
Harrison, Floyd P., and John W. Press. 1971. Timing of insecticide applications for
European corn borer control in sweet corn. J. Eoon. Entomol. 64(6):1496-1499.
Hudson, M. 1962. Field experiments with Bacillus thuringiensis and chemical
insecticides for the control of the European corn borer, Ostrinia nubilalis,
on sweet corn in southwestern Quebec. J. Eoon. Entomol. 55(1):115-117.
Hudson, M. 1963. Further field experiments on the use of Bacillus thuringiensis
and chemical insecticides for the control of the European corn borer,
Ostrinia nubilalis, on sweet corn in southwestern Quebec. J. Eoon. Entomol.
56(6):804-808.
Reed, John P- 1959. The role of granulated insecticides for control of sweet
corn pests in New Jersey. J. Eoon. Entomol. 52(5):972-974.
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TOMATOES, Lycopersicon esoulentwn
Tomato Fruitworm, Hel-iothis zea (Boddie)
The tomato fruitworm, Hel-ioth-is zea (Boddie) , is the most serious pest of
tomatoes in the United States and is especially damaging in the southern areas.
The fruitworm is a most versatile insect and is also known as the corn earworm
and cotton bollworm. Due to its overall importance, suggested practices for this
pest will be emphasized. Other insects and injury may be sampled and recorded
using essentially the same test method. Both foliage sprays and systemic granulars
applied to the soil should be evaluated. The specialized tomato growing procedure
of pole culture is covered under Tomatoes, Poled.
The following test methodology to determine the efficacy of insecticides to
control tomato fruitworms on tomatoes is very similar to the method previously
described under Cruciferae and Head Lettuce - Aphids and Thrips. Only the modifica-
tions of that method are noted below.
Experimental Design:—Plot size may vary greatly, depending on the anticipated
uniformity of infestation and population density- Unpublished data at the
Virginia Truck and Ornamentals Research Station, Painter, Virginia, indicates that
single row 13.7 m (45 ft.) long plots with adjacent untreated rows are entirely
satisfactory but would approach the minimum size. There is little evidence to
indicate that the buffer row was really necessary when the tomatoes were planted
in rows 1.8 m (6 ft.) apart. Harding (1971) favored plots two rows wide and 10.7 m
(35 ft.) long. Middlekauf et al. (1963) used larger plots, 10 rows 1.5 m (5 ft.)
wide by 15.2 m (50 ft.) long, when treatments were made in a commercial field.
Shorey and Hill (1963) obtained good results in commercial fields with plots
approximately one-half the size of the above.
Application and Equipment:—Hofmaster and Waterfield (unpublished data at
the Virginia Truck and Ornamentals Research Station, Painter, Virginia) have
utilized a Hudson Porta-Power high pressure sprayer, equipped with 37.9 liter (10
gallon) milk cans, in applying tomato insecticides. Application was at 935.4
liters/ha (100 gallons/acre) in 1.8 m (6 ft.) rows at 17.6 kg/cm2 (250 psi) with 6
nozzles/row. Some workers have gone to the other extreme, e.g. Harding (1971)
treated with a C02 tractor mounted sprayer operating at 2.1 kg/cm2 (30 psi) and
delivering 40.2 liters/ha (4.3 gallons/acre).
Due to the many variations possible in spraying techniques on tomatoes it
would seem rather useless to attempt to standardize, especially in field scale
plots. The most practicable end results for large plots will be obtained by
utilizing commercial spray practices best adapted to the area concerned.
Granules may best be applied with a commercial granular applicator specially
adapted for direct seeded tomatoes or transplants. Be sure to place granules in
the same relative positions consistently. Calibrate the granular applicator care-
fully for each formulation and rate and then plant the tomatoes directly without
resetting.
See also Cabbage Looper - Cruciferae for further details on ground and aerial
applications.
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-Ill-
Sampling:—Make direct counts of fruitworm damaged tomatoes. Fruitworms feed
mainly on the tomato fruit, attacking tomatoes of all sizes. They do not usually
confine their feeding to a single tomato but move from fruit to fruit. Sometimes,
however, the only evidence of a nearly grown fruitworm will be a very small pinhole
where the newly hatched fruitworm entered.
Treat on a 5-7 day schedule and check mature fruit for fruitworms. Since
fruitworm injury is often relatively light it is advisable to select 100 or more
fruit/plot. Harding (1971) sampled 200 fruit/plot while Shorey and Hill (1963)
checked over 2000 tomatoes/plot.
Fruitworms may destroy young tomatoes. If this situation exists, count the
total number of infested fruit/10-25 or more plants/plot and remove the small,
infested tomatoes as they are observed.
Take yield records and record both worm-free and infested fruit from entire
plot or representative area therefrom and convert yields to metric tons/ha or
tons/acre.
Colorado Potato Beetle, Leptinotarsa. decemlineata (Say)
Tomatoes are not favorite host plants of the Colorado potato beetle,
Leptinotarsa deoemlineata (Say), but suffer extensive damage in certain areas,
especially in the South where the tomatoes are often transplanted or seeded before
the potatoes emerge. The hungry overwintered beetles seek out the young tomato
plants and feed and lay eggs. Later, about the time the tomatoes mature, the
potatoes are harvested and the beetles, forced to seek food elsewhere, often feed
on the tomato fruits and foliage.
Sampling;—Count the number of potato beetle larvae or adults/10-25 plants.
Observe fruits at harvest for feeding injury. Take yields from entire plot or
representative area therefrom and convert to metric tons/ha or tons/acre.
Potato Flea Beetle, Epitrix eucimeris (Harris)
Overwintered potato flea beetles, Epitrix auGumeris (Harris), are often
present at tomato transplanting or direct seeding as in the case of the potato
beetle. Flea beetle damage by both adults to foliage and larvae to roots can be
very severe and actually kill the transplants or direct seeded tomatoes. Direct
seeded tomatoes are especially vulnerable and plantings may be completely destroyed
in several days.
Sampling:—Select at least 25 leaves/plot and count the flea beetle feeding
scars thereon, using the same technique as described by Hofmaster et al. (1967).
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In direct seeded tomatoes, count the number of injured plants/10-25 samples/
0.305 m (1 ft.) of row. Stand counts may be needed where infestations are severe.
If the plants have several leaflets, it may be possible to check feeding scars on
100 or more leaflets/plot. On calm days, actual counts of beetles/10-25 samples of
0.305 m (1 ft.) of row may be possible. Use of a special sampling cage similar to
the one developed by Hills (1933^ will be helpful.
Take yields from the entire plot or representative areas and convert to
metric tons/ha or tons/acre.
Aphids
Aphids seldom kill tomato plants but often stunt them and injure the fruit
clusters so that yields are reduced. The potato aphid, Macrosiphwn euphorblae
(Thomas), is the most common species. Aphids also transmit virus diseases of
tomato.
Sampling:—Select at least 25 leaves or terminals from as many different plants/
plot and count the aphids.
Take yields records; check fruit and plants for virus disease at this time.
Records may be taken from entire plot or representative section; convert to metric
tons/ha or tons/acre.
References
Creighton, C.S., T.L. McFadden, and R.B. Cuthbert. 1971. Control of Caterpillars
on tomatoes with chemicals and pathogens. J. Econ. Entomol. 64(3):737-739.
Creighton, C.S., T.L. McFadden, and R.B. Cuthbert. 1973. Tomato fruitworm:
Control in South Carolina with chemical and microbial insecticides 1970-1971.
J. Econ. Entomol. 66(2):473-475.
Hills, Orin A. 1933. A new method for collecting samples of insect populations.
J. Econ. Entomol. 26(4):906-910.
Harding, J.A. 1971. Field comparisons of insecticidal sprays for control of four
tomato insects in south Texas. J. Econ. Entomol. 64(5):1302-1304.
Hofmaster, R.N., R.L. Waterfield, and J.C. Boyd. 1967- Insecticides applied to
the soil for the control of eight species of insects on Irish potatoes in
Virginia. J. Econ. Entomol. 60(5):1311-1318.
Middlekauf, W.W., C.Q. Gonzales, and R.C. King. 1963. Effect of various insecti-
cides in the control of caterpillars attacking tomatoes in California. J.
Econ. Entomol. 56(2):155-158.
Shorey, H.H., and I.M. Hall. 1963. Toxicity of chemical and microbial insecticides
to pests and beneficial insects on poled tomatoes. J. Econ. Entomol.
56(6) .-813-817.
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TOMATOES, POLED (Fresh Market)
Tomato Fruitworm, Heliothis zea (Boddie) and Tomato Pinworm, Keiferia lycoper sicella
(Busck)
The following test methodology to determine the efficacy of insecticides to
control tomato fruitworm and tomato pinworm on tomatoes is very similar to the
method described under Cruciferae and Head Lettuce - Aphids and Thrips. Only the
modifications of that method are noted below.
M Crop and Location of Tests:—For the very early tests that involve "screen-
ing" only, plots can be 3 rows wide by 7.6 m (25 ft.) long. However, as the
compounds are tested past the initial screening stage, larger plots are recommended.
Plots 4-8 rows wide by 15.2 m (50 ft.) long should be large enough to prevent the
normal movement of adult moths from unduly influencing the results between plots
under normal fruitworm and pinworm pressure.
Since most commercial ground applicators treat 4 rows per swath, plots to test
commercial growing applications of insecticides should be 8 rows wide by 30.5 m
(100 ft.) long. The length to be long enough to harvest a representative sample of
fruit.
Application and Equipment:—Hy-Boy type spray equipment with vertical booms
on each side of each plant row using 3-5 nozzles (depending on the height of the
tomato plants) on each boom would provide good coverage when using ground equipment.
Air application equipment should be commercially acceptable.
The finished spray volume per acre would be dependent on size of tomato plants.
When foliar spray is applied by small hand or large ground equipment, 378.5-757.0
liters/ha (100-200 gals/acre) will give satisfactory results. When foliar spray
is applied by air, 56.8-75.7 liters/ha (15-20 gals./acre) will give satisfactory
results.
The time of application should be when small tomatoes first appear on the vine.
Since the control of the tomato fruitworm and the tomato pinworm require
preventive type treatments, the applications should be applied every 10-12 days
until harvest, making sure to observe the waiting period from the last application
to the harvest when using registered standard materials. The interval between
applications is dependent upon the area in which the test is conducted. When
feasible more than one time interval between applications should be evaluated.
Sampling:—Since poled tomatoes (fresh market) are harvested over a period
of several weeks, the sampling of the fruit for examination should be when there
are enough harvestable fruit to get a representative sample. Select tomatoes at
random over a wide area of the plot so that a representative sample can be taken,
but at all times keeping within a well buffered zone.
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Small screening hand plots that are 3 rows wide by 7.6 m (25 ft.) long should
have a fruit selection area one bed wide and 1.5 m (5 ft.) from the end of each
plot. This method would provide a 2 row buffer zone on each side of each plot.
Ground plots that are 4-8 rows wide by 15.2-30.5 m (50-100 ft.) long should
have a fruit selection area from the middle 2-4 rows and 10-20 ft. away from the
end of each plot. This method would provide a 2-4 row buffer zone on each side of
each plot.
Air plots that are 36.6 m (120 ft.) wide by 182.9 m (600 ft.) long should have
a fruit selection area 12.2 m (40 ft.) wide (middle one-third) and 30.5 m-45.7 m
(100-150 ft.) away from the end of each plot. This method would provide a 24.4 m
(80 ft.) buffer zone on each side of each plot.
A total number of 350-400 marketable tomatoes is selected at random per
each pesticide treatment, regardless of the number of plots.
Each tomato should be examined and recorded as damaged if found to have a
fruitworm or pinworm larva, or if only the damage is present on the fruit.
Extreme care should be taken to be sure that the damage is caused by the fruitworm
or pinworm. Normally one hole caused by one larvae is enough to grade the tomato
down or discard it as a "cull", so normally the number of holes or larvae per
tomato are not significant enough to record unless "severity of infestation" type
data is requested. The total number of tomatoes infested is recorded as well as
the percent tomatoes infested.
Plants in plots treated with any new pesticide being tested should be examined
at least once to determine if there is any detrimental effect on yield. This is
especially important when the pesticide is applied during the early stages of
plant development, such as when there are many blossoms on the vine. All tomatoes
in a given area of the central part of the plot should be harvested. Marketable
tomatoes should be harvested in commercial field boxes, and that number converted
to "boxes yield per ha (acre)". Because poled tomatoes are harvested several
times, it is recommended that more than one harvest be made for the yield records.
References
Creighton, C.S., T.L. McFadden, and R.B. Cuthbert. 1971. Control of caterpillars
on tomatoes with chemicals and pathogens. J. Eoon. Entomol. 64(3):737-739.
Creighton, C.S., T.L. McFadden, and R.B. Cuthbert. 1973. Tomato fruitworm:
Control in South Carolina with chemical and microbial insecticides. J. Eoon.
Entomol. 66(2):473-475.
Hale, R.L. 1967-1973. Annual reports on file with the Entomology Department,
University of California, Riverside, California.
Hale, R.L. 1973-1974. Unpublished data.
Middlekauf, W.W., C.Q. Gonzales, and R.C. King. 1963. Effect of various insecticides
in the control of caterpillars attacking tomatoes in California. J. Eoon.
Entomol. 56 (2):155-158.
Shorey, H.H., and R.L. Hale. 1963. Toxicity of chemical and microbial insecticides
to pest and beneficial insects on poled tomatoes. J. Eoon. Entomol.
56(6):813-817.
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GPEENHOUSE VEGETABLES
Greenhouse vegetables are important high value crops in many states.
Tomatoes are most widely grown: lesser crops are lettuce, cucumber, radish,
cress, endive and several other vegetables. These crops are often rotated
such as tomatoes in fall and spring, with lettuce as a winter crop. Spring
crops of vegetable plants and ornamental or bedding plants are grown by
some operators. A fall crop of tomatoes is grown on some vegetable farms
where the greenhouses are used in late winter and spring for growing vege-
table seedlings for early spring field plantings.
Approximately 30 species or groups of closely related species of insects,
mites, slugs, snails, sowbugs, and symphylans feed on foliage or fruits, stems
and roots, or destroy the seedlings (Smith 1959).
The pesticides for use on greenhouse vegetables are applied in several
ways:
Sprays Equipment for applying liquid sprays varies from knapsack
sprayers for spot spraying or in small greenhouses, to small portable power
sprayers for narrow aisles, to stationary pumps with extensive pipe or hose
lines.
Low volume pesticides are applied with special equipment and special
formulations.
Aerosols Liquified gas propelled aerosols containing the dissolved
insecticide in methychloride with a mutual solvent when needed are released
with considerable turbulence (Smith et al. 1947, Smith and Lung 1948, Smith
1950). Mechanical aerosols with insecticide in a volatile solvent are dis-
charged with equal turbulence by high velocity air streams from lightweight,
portable equipment including such machines as the Solo, Klip-On, Florafume
or Spacemaster foggers, Nicrogen and others (Johnson et al. 1965). Thermo-
generated fogs produced from insecticides in special petroleum distillates
are discharged also with turbulence by such machines as Dyna-Fog Model "70"
or Flora-Fog (Snetsinger 1964).
Fumigants Toxic vapors from granular calcium cyanide scattered on aisle
surfaces or from released volatile pesticides (dichlorvos) through the poly-
ethylene tube ventilating system are further distributed by normal convection
currents from the heating system or turbulators (Weigel 1926, Smith and Ota
1967).
Smokes Combustible powders containing the insecticide in a slow burning
mixture generate smoke with turbulence that becomes distributed throughout
the greenhouse. Smokes are especially useful for treating small greenhouses.
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By methods outlined above, the greenhouse operator can program his pest
management operations that require a minimum of time and maximum safety to
operators and his high value crops (Fulton and Smith 1958) . Minimum effective
dosages against the vulnerable stages of the pest are emphasized in most con-
trol programs. Pest control in greenhouses is largely dependent upon chemi-
cals with vapor toxicity of short duration and minimum periods of residual
action which permit harvest with short waitinp periods (Fulton et al. 1950).
However, these vegetable crops are more sensitive to chemicals and to tempera-
ture changes when grown in the greenhouse than when grown in the field. There-
fore, the greenhouse operator must recognize optimum conditions of light,
temperature and relative humidity for applying pesticides.
In evaluating the efficacy of candidate pesticides for use on pests affecting
greenhouse vegetables discussed in this report, the impact they may have on
non-target species that may be included in integrated control programs should
be determined.
Minor Pests of Greenhouse Vegetables
At least 13 species of insects and related organisms sporadically damage
greenhouse vegetable crops on which they become established from neighboring
outdoor crops, ornamentals, or weedsr or they are introduced on infested
plants or other materials such as shipping containers.
Test methods for obtaining data for these minor pest species listed below
have not been developed in this report.
Broad mite
Citrus mealybug
Fungus gnat
Garden fleahopper
Grape mealybug
Greenhouse thrips
Mushroom mite
Onion thrips
Ringlegged earwig
Sowbug
Tomato russet mite
White mold mite
Wireworm
- Polyphagotarsonemus lotus (Banks)
- Planococcus c-itr-i (Risso)
- Lycor-ia inconstans (Fitch)
- Halticus bracteatus (Say)
- Pseudococcus mari-tinrus (Ehrhorn)
- Heliothrips haemorrhoidalis (Bouche)
- Tyrophagus lintneri. (Osb .)
- Thrips tabaci, (Lindeman)
- Euborellia annulipes (Lucas)
- Armad'ill'idu'm vul-gare (Latr.)
- Aculops lycopersici (Massee.)
- Er-iophyes cladop'bt'hirus (Nalepa)
- Melanotus spp.
References
Fulton, R.A., and F.F. Smith. 1958. Respiratory protective devices:
Methods for testing them against pesticides. Agric. Chem. Aug. £• Sent.
Fulton, R.A., F.F. Smith, and M.S. Konecky. 1950. Comparative toxicity of
vapors of four organic phosphates to chrysanthemum aphid and two-spotted
spider mite. J. Econ. Entomol. 43:940-1.
Johnson, G.V., A.H. Yeomans, and F.F. Smith. 1965. Mechanical aerosol
applications in greenhouses. Flor. Exc. 111(8):34-37, 60, 69.
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Sleesman, J.P., and R.K. Lindquist. 1971. Seek effective controls for green-
house whitefly. Greenhouse Veq. Res. Sunm. , Ohio Pep. OAKDC , Wooster,
Ohio. 56(3):35-37.
Smith, F.F. 1950. Tetraethyl Dithiopyrophosphate in Aerosols for Control of
Greenhouse Insects, USDA BEPQ Circular F- °m (Virneo) .
Smith, F.F. 1959. Control of Insect Pests of Greenhouse Vegetables. USDA
Agric. Handbook #142. 25pp.
Smith, F.F., R.A. Fulton, P.H. Lung, and P. Brierley. 1947. Potent new
insecticide and new method undergo thorough trial. Flor. Pev.
99(2569) : 31-35. Feb. 20.
Smith, F.F., P.P. Lung, and R.A. Fulton. 194P . Parathion in Aerosols for
the Control of pests on Greenhouse Plants. U?DA BEOP Circular E-75Q
(mimeo) .
Smith, F.F., and A.K. Ota. 1967. Control of insects in a greenhouse
equipped with a polyethylene tube ventilating system. FToT. P&v .
140(3636) ;11, 68. Aug. 3.
Smith, F.F., A.K. Ota, and A.L. Boswell. 1970. Insecticides for control of
the greenhouse whitefly. J. Econ. Entomol. 63:522-27.
Snetsinger, R. 1964. Pesticide application in the greenhouse. (Reprinted)
Suffolk Country Farm News. May, p. 32. (New York).
Weigel, C.A. 197.6. Calcium Cyanide as a Fumigant for Ornamental Greenhouse
Plants. USDA Dept. Circular 380, 16 pp.
At least four species of aphids are commonly found on greenhouse vegetables.
The foxglove aphid Acyrthosiphon solani (Kltb.), green peach aphid Myzus persicae
(Sulzer) , melon aphid Aphis gosspyii Glover, and potato aphid MacrosipPvw
euphorbiae (Thomas) cause stunting and curling of new growth, yellowing and
death of older leaves. Fruits and foliage become coated with honeydew followed
by black sooty mold. In addition, aphids transmit cucumber mosaic virus to
tomatoes and cucumbers.
Aphids are readily controlled with soil systemics, also with aerosols,
smokes, fumigants., or sprays on most crops except on dense foliage of lettuce
or cucumbers. To be effective, early season control is important.
Crop and Location:—Plants of cucumber, lettuce, tomato, cress, or
radish are grown in 10 cm (4 in.) pots or larger containers and infested with
desired species of aphid from test colony.
For the tests, use vigorous aphid colonies, composed predominately of
apterous nymphs and adults and free of parasites, predators, and fungus
infections that would confound the results.
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Experimental Design:—Groups of 4 or more plants, each of desired test
crops and desired aphid species, may be used for systemics applied to the soil,
for sprays applied with knapsack sprayer, or for spacing among other plants in
greenhouse units 28.3 m^ (1000 ft.3) or larger houses for testing aerosols,
mists, combustible powders or smokes, and fumigants.
Each formulation should be compared with a standard formulation of known
performance and with an untreated control.
After minimum effective treatment has been established, make series of
applications with natural infestations in commercial greenhouses: place pots
of infected test plants at intervals to determine efficiency of control and
effect on crop.
See Leafminers for other details.
Application and Equipment:—See statement under Leafminers.
Sampling:—Make 24-hour posttreatment count of dead or moribund aphids
that drop from plants onto papers placed beneath the pots before treatment,
also those that lodge on plant parts. Make 1-day and 3-day count for
survivors.
In naturally infested commercial crop, make 1-day and 3-day counts
posttreatment for mortality. Make counts at 7 day intervals for buildup of
population to determine need for retreatment.
Record observations on host plant reaction such as tip burn on lettuce,
chlorosis or flower bud abscission on cucumber or tomato following treatment,
Analysis and Reporting of Data:—See statement under Leafminers.
Reference
Smith, F.F. 1962. Control of Insect Pests of Vegetables, USDA Agric.
Handbook #142. 25 pp.
Beetles
Spotted cucumber beetles, D-idbrot-ica unidecimpunctata howardi Barber, and
striped cucumber beetles, Acalyrma wittata (Fabricius) , damage outdoor crops
and enter the greenhouse in spring and autumn. The.v feed on stems and foliape
of cucumber and infect plants with bacterial wilt; they also attack tomato and
lettuce.
Several species of flea beetles, but especially potato flea beetles,
Epitri.x cucumer-is (Harr.) , enter greenhouses in spring and fall and damage
young tomato plants.
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D an Location:—These pests as adult beetles are sporadic invaders on
, — " ^ i»•— u i_ r t-> ^- o CLO ava. *_j. _i_ L- LJCC^I LCO CLJ_C_ oL'^'-i-ci.^i.j^^^ j_iiv
greenhouse vegetable crops and normally do not breed on them. Control
esigned for treating entire greenhouses are therefore essential.
measures
n1--If a screening program for new chemicals is desired,
follow procedures for rearing and testing insects under Leaf Eating Caterpillars.
For tests with sprays, select randomly located groups of 20-30 cucumber
or tomato plants or comparable areas of cucumber, lettuce, or tomato seedlings
that are being damaged by one or more of these pests .
For tests with aerosols or fumigants, select units of 28.3 m3 (1000 ft.3)
or commercial greenhouses.
Include untreated control and a treatment with test chemical of known
performance as a standard for effectiveness.
Application and Equipment:—See Leaf Eating Caterpillars.
Sampling:—Make pretreatment counts of adults present in 3 or more randomly
located groups of plants in infested greenhouses.
To obtain information on mortality of beetles in treated areas, place
sheets of paper or polyethylene under groups of plants before treatment.
Make 24 hour posttreatment count of living beetles that are present on the
plants and record those dropping onto sheets and record on basis of m2
(10.8 ft. 2). The dead beetles on sheets may not reveal total mortality since
insects may disperse for various distances before they succumb.
Make insect injury ratings of 1-5 on seedling tomatoes or other affected
hosts 24 hours posttreatment. Fully describe leaf damage such as seedlings
with injured leaves and cucumber plants with gouged stems.
Record host plant injury following application of test material 1 day
and 7 days posttreatment, including foliage injury such as chlorosis,
marginal burn, also flower bud abscission on tomatoes and cucumbers.
Analysis and Reporting of Data:—See statement under Leafminers.
Eeference
Smith, F.F. 1959. Control of Insect Pests of Greenhouse Vegetables.
USDA Agric. Handbook /f!42. 25 pp.
Cutworms
Several species of cutworms including the black cutworm Agrotis ip si-Ion
(Hufnagel) , variegated cutworm Peridroma sauaia (Hubner) , and the dingv cutworm
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Feltia subgothica (Haw.) attack lettuce, cucumbers, tomatoes, and cress,
especially in the seedling stage. The variegated cutworm and others known
as climbing cutworms also climb older plants and feed on leaves, buds, and
fruit. All hide in the soil or mulch during the day and feed at night. In
the greenhouse, adults and young larvae have been controlled by aerosols
containing parathion or malathion. Baits containing bran, molasses, sometimes
other ingredients, and a toxicant are effective against older cutworm larvae.
Crop and Location:—For tests in greenhouses with cutworm infestations
on lettuce, tomato, cucumber, or cress, select plots of adequate size to reduce
influence of larval dispersal from contiguous plots.
Experimental Design:—If facilities are available, cutworm larvae may be
reared and released in plots 1 or 2 days before treatment. See Leaf Eating
Caterpillars for rearing methods.
All treatments should be replicated 3 or more times for evaluation of
results. Also include an untreated control and a treatment with test chemical
of known performance as a standard for effectiveness.
Application and Equipment:—For application of aerosols, fumigants , or
ground sprays, see this section under Leaf Eating Caterpillars.
Bran baits prepared with or without molasses and with the test compound
as toxicant are broadcasted late in the afternoon at rate of 11.2 to 22.4 kg/ha
(10 to 20 Ib/A) (Metcalf et al. 1962). It should not be scattered on the
plants but directed to the ground.
Sampling:—Make direct counts of dead larvae found in soil depressions
around the base of injured plants.
Make counts of cutworm-injured plants at 1 and 7 days posttreatment.
Analysis and Reporting of Data:—See statement under Leafminers.
Reference
Metcalf, C.L., W.P. Flint, and R.L. Metcalf. 1962. Destructive and Useful
Insects. McGraw-Hill Book Co., New York. 1083 pp.
Garden Symphylan
The garden symphylan Scutigerella immaculate. (Newport) is a widespread
pest of vegetable crops, fruits, and ornamentals in 25 states and occurs both
in greenhouses and out-of-doors. High soil temperatures in southern states
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pest ri-rr soils in areas of low rainfall limit even wider distribution of this
AT,,*-' i_ rri8ation of dry-land areas promotes further distribution of this pest
(Waterhouse 1910}
-, . 1S ng infestations in greenhouses are usually suppressed by pre-
ing soil fumigations with ethylene dibromide or D-D mixture as used for
nematode control of soil sterilization with steam or hot water, but these
of effe ' When the symphylans penetrate to soil depths below the zone
o e ective treatment or they migrate from untreated areas through drainage
tiles, gravelly soil, or earthworm tunnels. They survive by feeding on organic
matter trom manure or decaying vegetable matter between crops. For reproduc-
1966) £Ver' they req-uire living plant roots of the growing crop (Shanks
Plants injured by symphylans are stunted, grow slowly or die due to the
severe pruning of the root system. Soil drenches with lindane have been an
effective supplementary post-planting treatment in greenhouses on both
vegetables and ornamentals.
Field experiments have demonstrated that certain chemicals are highly
effective in protecting crops from symphylan damage. These chemicals seem
worthy of testing for effectiveness-cm vegetable crops in the greenhouse.
Complete control of symphylans for 18 weeks in Oregon resulted from soil
treatments or by dipping bare roots and stems of broccoli plants being trans-
planted to the field (Berry and Crowell 1970). In Pennsylvania applications
in the row or broadcast resulted in protection of corn and beans for 62 days
(Gesell and Hower 1973).
Since natural infestations in greenhouses tend to be localized and
populations vary, performance data may not be readily obtained. Ramsey (1971)
proposed the desirability of artificially infesting experimental plots and
outlined a procedure for mass rearing symphylans.
Rearing colonies of garden symphylans can be accomplished by placing 20
adults in a .947 liter (1 quart) glass canning jar with 2.5 cm (1 in.) of
gravel in the bottom and loosely filled with soil at 25% soil moisture and
held at 21.1°C (70°F). Fresh carrot roots are supplied twice weekly as food
(Shanks 1966). In later studies, Berry (1972) used ground hemlock bark at
30% moisture and temperature of 24°C (75.2°F). By supplying both lettuce
leaves and carrot roots as food, he obtained 20 fold increase in 6 months.
Portions of the media containing symphylans are distributed among the plots
(Ramsey 1971).
Crop and Location:—Young tomato, cucumber, or lettuce plants should be
set in infested areas in the greenhouse. Radish and cress should be seeded.
Plots of tomatoes and cucumbers should be 3 rows wide and 5 m (16.4 ft.) long.
Plots of lettuce, radish, and cress should be of comparable size.
Experimental Design:—Symphylan populations already present may be
supplemented from reared colonies to insure a uniform infestation. Allow
several days time for symphylans to become distributed before treatments are
applied. Each series of tests should be replicated 4 or more times in random-
ized block design. A known effective treatment as a standard and an untreated
check should be included for comparison with candidate materials.
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Application and Equipment:—Dipping roots of transplants can be done at
time of setting plants in the growing sections of greenhouses. Measured
quantities of drenches can be applied to the soil at the base of each plant
after they have been transplanted from pots to greenhouse beds, or in a
furrow beside the plants made with a wheel hoe. Granules can be applied in
the furrow for band treatments with a hand shaker. Broadcast treatments on
small plots can be made with a hand shaker and to larger plots with equipment
generally available for applying measured quantities of granules or powders
to agricultural crops. The granules can be incorporated in the soil with a
garden rotary cultivator (Gesell and Hower 1973) .
Sampling^—Make uniform soil samplings: 2 or more per plot, to a depth of
20.32 cm (8 in.) to include part of the root zone of the growing plants and
record the living symphylans in the sample by visual examination or more
accurately by flotation of symphylans by stirring the soil sample in water.
Pretreatment samplings should be made in each plot. Make weekly samplings
posttreatment to determine the residual effectiveness of the treatment.
Make observations on growth effects of symphylan damage on the crop and
differentiate from damage due to chemical treatments.
Take yield data of harvested crops.
Analysis and Reporting of Data:—See statement under Leafminers.
References
Berry, R.E. 1972. Garden symphylan: reproduction and development in the
laboratory. J. Boon. Entomol. 65:1628-32.
Berry. R.E., and H.H. Crowell. 1970. Effectiveness of Bay 37289 as a
transplant dip to control the garden symphylan in broccoli. J. Fcon.
Entomol. 63:1718-19.
Gesell, S.S., and A.A. Hower. 1973. Garden symphylan: comparison to row
and broadcast application of granular insecticides for control. J.
Econ. Entomol. 66:822-23.
Ramsey, H.L. 1971. Garden symphylan populations in laboratory cultures.
J. Econ. Entomol. 64:657-60.
Shanks, C.H. 1966. Factors that affect reproduction of the garden symphylan,
Scutigerella -immaculata. J. Eoon. Entomol. 59:1403-06.
Waterhouse, J.S. 1970. Distribution of the garden symphylan, Scutigevella
i-mmaculata, in the United States-a 15-year survey. J. Econ. Entomol.
63:390-94.
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GreenhouE
greenhouse whitefly Trialeurodes vaporariomm (Westwood) is
the most serious pest of greenhouse vegetables and ornamental
crops and is established in greenhouses throughout the United States.
inis wnitefly does not survive the winter out-of-doors in cold climates
uuc it breeds during the summer on vegetables in commercial fields and home
gardens including squash, potatoes and tomatoes, also on numerous ornamentals
and weeds. It is being distributed on vegetable and ornamental plants
from greenhouses and garden centers. Flying adults reinfest greenhouse
crops in the fall. Greenhouse cucumbers and tomatoes are most seriously
infested because of the higher temperatures at which they are grown: but
lettuce, radishes, and cress are also infested.
Infested foliage becomes yellowish-green and the plants are stunted from
whitefly feeding on plant sap. Foliage and fruits are often blackened by
sooty fungus that grows on the honeydew secreted by the adults and nymphs.
Reduction in yields of tomatoes results from sooty mold fungus that grows on
honeydew deposits, also by direct feeding damage on the foliage (Lindquist
et al. 1972).
At normal temperatures for growing greenhouse tomatoes, the life cycle
from egg laying to adult is about 35 days - eggs, 11-12 days: first nymphal
stage, 2-4 days: second, third and fourth nymphal stages, 4 days each: and
quiescent pupal stage about 9 days. Adults mate and begin laying eggs within
20 to 40 hours and continue to lay eggs daily for 30 to 40 days.
The motility of adults and their daily reproduction over several weeks
results in infestations in all stages of the insect on the same plant.
Successful control of greenhouse whitefly has been dependent upon regularly
timed applications of the most widely used insecticides that kill the adults,
the newly hatched motile nymphs in the first instar and the sessile nymphs
in the second instar. Nymphs in the third and fourth instars are more resis-
tant than younger nymphs, the pupae are highly resistant, and the eggs are little
affected by most registered chemicals (Gentile 1972, Krueger et al. 1973,
Smith et al. 1970, Webb et al. 1974).
Crop and Location: — For the preliminary tests to obtain data on mortality
of various whitefly stadia, all plants should be grown under isolation before
and after infestation and treatment .
Select a variety of tomato or cucumber commonly grown in commercial
greenhouses. For preliminary tests, an excellent host plant is the Henderson
bush lima bean, seedlings of which are easily grown: adult whiteflies readily
oviposit on the primary leaves, and the nymphs and pupae are uniformly exposed
for treatment and examination (Smith et al . 1970, Webb et al . 1974).
For soil applications of chemicals with systemic action and certain fumi-
gants or aerosols (mechanical, liquified gas, or thermal), circumstances may
make it necessary to conduct a series of applications on mixed populations in
larger greenhouse units: or infested plants with whiteflies of known age can be
placed at intervals throughout the compartment or experimental greenhouse unit.
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Experimental Design:—Groups of infested plants with 25 to 50 insects
per leaf and in desired developmental stage or age group should be replicated
three or more times for each material and dosage rate. Each series of tests
should include comparable groups of plants that receive (a) a known effective
treatment as a standard and- (b) no treatment. Treated and untreated groups of
plants should be isolated to prevent posttreatment reinfestation.
Application and Equipment:—To obtain whitefly nymphs of known age and
development, expose groups of plants successively for 2-8 hours to caged
ovipositing adults. Continue to expose other groups at 2-3 day intervals until
all stages are represented in the series. Avoid excessive egg deposition by
prolonged exposure to adults and later overcrowding of nymphs, which lead to
high mortality in checks. Kill adults remaining on plants after exposure
using dichlorvos vapors (Smith 1970, Webb et al. 1974) and reisolate plants
until time for treatment.
Sprays may be applied with 7.5 liter (2 gal.) compressed air sprayer
operating at 2.1-4.2 kg/cm^ (30-60 psi) and wetting both upper and lower leaf
surfaces. Also, uniform coverage can be assured by dipping plants in the spray
formulation.
Greenhouse compartments of 28.3 m^ (1000 ft. ) or larger are needed for
testing materials in gas propelled aerosols using methyl chloride as propellent,
mechanical aerosols with methylene chloride or other volatile solvent,
microgenerators using appropriate formulations of test material, or fumigants
such as granular calcium cyanide, also resin strips or other materials as
corn cobs impregnated with dichlorvos (Smith et al. 1970).
Soil treatments with systemic insecticides - see statement under Leafminers,
Sampling:--Samplings to determine mortality of immature stages are made
at 7 and 14 days posttreatment. Ten or more leaf discs, 1 cm (0.394 in.)
diameter, cut with leaf punch or cork borer (Smith et al. 1970), entire
leaflets, or half leaves (Webb et al. 1974, Krueger et al. 1973) are collected
at the same relative position on treated and untreated plants. Examinations
should be made with microscope and illumination so that dead and living nymphs
can be differentiated. From 100 to 200 or more individuals should be included
in sample counts from each treatment.
Mortality of adults on plants treated in plots on the growing crop can
be made by leaf counts before and after treatment and by dead adults on
squares of black paper placed beneath the plants at time of treatment (Smith
et al. 1970, Webb et al. 1974). Mortality of immature stadia by leaf disc
or leaflet samples can also be made on the growing crop after a series of
scheduled applications have been made (Smith et al. 1970).
Analysis and Reporting of Data:—See statement under Leafminers.
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References
Gentile A r 1070 A -,
•<-• iy/2. An evaluation of SBP 1382 for the control of whiteflies
on poinsettia. FZor>. Rev. April 13, 19-20.
Llndauist R.K., T.T.L. Bauerle, and R.R. Spadafora. 1972. Effect of the
65^1406-08 y °n ylelds of greenhouse tomatoes. J. Econ. Entomcl-
Krueger, H.R., R.K. Lindquist, J.F. Mason, and R.R. Spadafora. 1973. Application
of methomyl to greenhouse tomatoes: greenhouse whitefly control and
residues in foliage and fruits. J. Econ. Entomol. 66:1223-24.
Smith, F.F., A.K. Ota, and A.L. Boswell. 1970. Insecticides for control
of the greenhouse whitefly. J. Econ. Entomol. 63:522-27.
Webb, R.E.,^F.F. Smith, A.L. Boswell, E.S. Fields, and R.M. Waters. 1974.
Insecticidal control of the greenhouse whitefly on greenhouse ornamentals
and vegetable plants. J. Econ. Entomol. 67:114-118.
Leafminer
The vegetable leafminer (Liriomysa sp.) which has been identified as
L. rmnda Frick (Smith et al. 1962) or L. sativae Blanchard (Lindquist and
Krueger 1975) is a major pest of ornamentals, lettuce, tomatoes and cucumbers
in northern greenhouses. The same species or closely related species damage
greenhouse crops in many states. This vegetable leafminer was probably in-
troduced into northern greenhouses from the Gulf States or California and
was distributed on chrysanthemums or other ornamentals. Its wide host range
includes a large number of vegetable crops, ornamentals and weeds. It does
not survive the cold winters in the north but breeds throughout the year in
greenhouses. Leafminers infest nearby outdoor crops during the summer, then
return to new greenhouse crops in the autumn.
Leafminer injury consists of small stippled spots or punctures in young
leaves caused by the female ovipositor. The oozing droplets of sap supply food
for both males and females. The more conspicuous injury, however, is the
serpentine mines caused by feeding larvae from eggs deposited in older leaves.
A single larval mine per tomato leaflet causes a measurable reduction in yield
(Wolfenbarger and Wolfenbarger 1958).
In most field experiments (Wolfenbarger 1958), insecticides have been
evaluated on the decrease in numbers of mines in treated plots. Contact or
residual activity of the insecticides on adults, eggs and larvae were not
differentiated. Tests for control of pupae in the soil have not been successful.
For leafminer control on greenhouse crops, it is essential to establish
minimum effective dosage rate and treating schedule by testing the insecticide
against eggs and larvae of known age (Smith et al. 1974). Intervals between
applications of 5 or 7 to 8 days will depend upon (1) residual action of test
compound, (2) controlling the larva while young and before it has caused
extensive damage, and (3) greenhouse temperatures that affect the developmental
rate of the leafminer.
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Crop and Location:—Select a susceptible variety of host crop plant for
initial tests; also Henderson bush lima bean (Phaseolus lunatus} may be used
since it is easily grown and supports high populations of larvae in primary
leaves (Webb and Smith 1970). Uniform infestations can be obtained in groups
of plants by exposing them to adults in a rotating exposure cage (Smith et
al. 1970). Test plants should be grown in containers so that groups of plants
with different aged insects can be moved to: (1) sites for precision spraying,
or (2) to greenhouses for treatment with sprays, aerosols or fumigants, and
(3) to isolated greenhouse units or growing areas to prevent posttreatment
reinfestation. If circumstances make it necessary to select test plants from
randomly infested plants in a commercial greenhouse, the leaves containing
larvae in an early stage of development should be tagged and observed for
results after treatment (Lindquist et al. 1973, Lindquist and Krueger 1975).
Experimental Design:—Groups of four or more pots of plants containing a
total of 100 or more leafminers in each age group should be treated as a unit
for each dosage level and within the range of greenhouse temperatures required
for commercial production of the crop or crops involved. Three or more
replications per treatment are desirable for evaluation of results.
When the minimum effective dosage has been established, make tests for
phytotoxicity on host crops at increased dosage (up to 2X) at the normal
temperature and also at 5°C (9°F) elevated temperature.
Follow requirements of greenhouse culture by making treatments during
periods of daylight or darkness to avoid undue plant stress (water loss and
wilting or leaf burn from high temperatures). Observe requirements for
closing and opening ventilators for releasing insecticide vapors and control-
ling the temperature.
Application and Equipment:—
Foliage Application - Depending upon the test chemical and the formulation,
applications can be made with knapsack sprayers operating at 2.1-4.2 kg/cm?-
(30-60 psi) and delivering 187.1-935.4 liters/ha (20-100 gallons of water/acre).
Sprays should be applied to both upper and lower leaf surfaces. For
treating larger plots on the growing crops in greenhouses are specially designed
equipment that includes power sprayers, micronizers, backpack mist blowers,
mechanical aerosol machines, thermogenerators for fogs or liquefied gas
aerosols in special containers, and nozzles for release and distribution in the
greenhouse or through polytube ventilating systems. The test chemical should be
incorporated in formulations required for efficient performance in any of these
machines. The nature of the chemical may make it adaptable for use in some
machines but not others. For example, chemicals for use in liquefied gas
aerosols must be soluble in the propellent gas or in a standard non-phytotoxic
solvent that blends with the propellent.
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ee1 Application ~ Systemic insecticides for control of leafminers in the
measure °Uld be aPPlied as granules with a special applicator that accurately
195? TS j quantity desired for a given sized container or bed area (Smith
ujz., Lindquist and Bauerle 1972).
HT- lnsecticldes in emulsions or solutions are applied to the soil
(I ^o^Nat ^esi§nated dosages for various sized containers or bench areas
^mitn 1V02;, which will facilitate computation to kg/ha (Ib/acre) dosage rates.
_ Sampling:— Both treated and untreated plants should be isolated from
infested crops to prevent straying leafminer adults from ovipositing post-
treatment. Mortality of leafminer larvae in leaves of treated plants can be
determined by direct examination. Cessation of feeding and shriveling of
killed larvae can be observed under low magnification one day after treatment.
By examination of foliage 4 to 7 days after treatment, dead and living or
emerged larvae can be determined by appearance of the mines (Smith et al. 1962).
Dead larvae will be found in partially developed mines. Living larvae occur
in more fully developed mines or they will have emerged and pupated at the 7-day
count.
Analysis and. Reporting of Data: — Data should be compared using a valid
statistical test for significance such as Duncan's new multiple-range test.
Treatment performance should be compared with untreated checks and one
or more highly effective insecticides that have been reported in literature
or accepted as standard for commercial control.
References
Lindquist, R.K., and W.L. Bauerle. 1972. Evaluation of granular insecticides
for control of leafminers and whiteflies on greenhouse tomato seedlings.
Greenhouse Veg. Res: Res. Sumrn. 58. OARDC, Wooster, Ohio. April.
Lindquist, R.K., H.R. Krueger , J.F. Mason, and R.R. Spadafora. 1973. Applica-
tion of diazinon to greenhouse tomatoes: vegetable leafminer control and
residues in foliage and fruits. J. Econ. Entomol. 66:1001-2.
Lindquist, R.K., and H.R. Krueger. 1975. Application of acephate to
greenhouse tomatoes : external vs . internal foliage residues , and vegetable
leafminer control. J". Econ. Entomol. 68:122-3.
Smith F.F. 1952. Conversion of per acre dosages of soil insecticide to
equivalents for small units. J". Econ. Entomol. 45:339-40.
Smith F.F. , A.L. Boswell, and H.E. Wave. 1962. New chrysanthemum leafminer
species. Flor. Rev. 130:29-30.
Smith F.F., R.E. Webb, and A.L. Boswell. 1974. Insecticidal control of a
vegetable leafminer. J. Econ. Entomol. 67:108-10.
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Smith, F.F., R.E. Webb, A.L. Boswell, and G.F. Combs. Jr. 1970. A
circular rotating cage for obtaining uniform oviposition by Liriomysa
rrrunda in exposed plants. J. Fcon. Entomol. 63:655-6.
Webb, R.E.. and F.F. Smith. 1970. Fearing a leafminer Liriomyza rrrunda.
J. Econ. Entomol. 63:2009-10.
Wolfenbarger, D.O. 1958. Serpentine leafminer: brief history and summary
of a decade of control measures in South Florida. J. Econ. Entomol.
51:357-9.
Wolfenbarger, D.A., and D.O. Wolfenbarger. 1966. Tomato yields and leafminer
infestations and a sequential sampling plan for determining need for
control treatments. J. Econ. Entomol. 59:279-83.
Leaf Eating Caterpillars
Several species of lepidopterous pests of field grown vegetable crops also
are annual threats to greenhouse vegetable crops, especially in the fall when
their moths enter the greenhouses and initiate infestations on lettuce, cucumbers,
and tomatoes as well as other vegetables and ornamentals. It is well known that
the early developmental stages of armyworms, cabbage loopers, corn earworms,
and other lepidopterous pests are much more susceptible to insecticides than
are older larvae (Harris et al. 1975). Early detection of infestations and
prompt treatment in greenhouse vegetable crops are important for efficient
control. Control programs should be based on tests against one week old larvae
or, at the most, up to third instar larvae (Lindcmist 1972, Harris et al. 1975,
Smith 1959). By applying the pesticide at minimal dosage rates and at regular
intervals against the susceptible younger larvae, possible phytotoxic effects
against the more tender greenhouse crops can be reduced.
Since these pest species are also important pests of outdoor commercial
vegetable crops in many parts of the country, data on promising new materials
that result from field experiments should give leads to materials that may be
adaptable to greenhouse crops.
Armyworms of several species, including the fall armyworm Pseudaleti-a
unipunctata (Haw.) and the yellow striped armywormProden-ia orn-ithogall-i Guen,
are fairly regular pests in fall crops of greenhouse vegetables. Armyworm
moths enter the greenhouses in the fall. Their larvae feed on cucumber, lettuce
and tomato. They also chew out large areas in the side of foliage of tomato
fruits.
In recent years the beet armyworm Spodopteva exi,gua (Hbn.) has become an
increasingly serious pest on both vegetables and ornamentals in northern
greenhouses. It has usually been introduced on cuttings or plants from the
south. Once established, the beet armyworm becomes a persistent pest, since it
is less readily controlled by available pesticides than are the other above-
named armyworms. If not controlled, beet armyworms continue to breed and damage
crops throughout the winter.
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"1 flin m°ths of the corn earworm or tomato fruit worm enter the
SUTnmer or earlY fall and lay their eggs on tomato foliage.
larVae feed at first °n the foliage; later they cut small entrance
s r fruits and devour the interior. A single larva may damage several
conta'"' of y°uni? larvae on the foliage has been accomplished with aerosols
effective8 Parathion and malathion (Smith 1959) . Dichlorvos has also been
f 11 Th lo°per Triefoplusia ni (Hbn.) moths enter greenhouses in the
11.
insect is probably more widespread and the most generally serious
caterpillar pest of greenhouse vegetables and ornamentals. If uncontrolled, cab
bage loopers continue to breed on greenhouse crops throughout the winter.
Cabbage loopers feed on foliage of tomato, cucumber, cress and radishes and are
especially damaging to lettuce where they are also most difficult to control.
Prompt and regular applications of an effective insecticide are essential
since young larvae and the adults of the above species are more readily
killed than older larvae by parathion, malathion or dichlorvos in aerosols
(Smith 1959, Harris et al. 1975).
Crop and Location: —Grow test plants of lettuce, tomato, cucumber or other
crops in 10-15 cm (4-6") pots in isolation to prevent infestation by unwanted
pests. To obtain caterpillars of each species, all of known age and in the same
stage of development, infest groups of plants with eggs from moths reared from
local infestations or captured in black lights (Harris et al. 1975). Hold
eggs for hatching and rearing to one week old larvae (Lindquist 1972) . Harris
et al. (1975) used a more precise test method by rearing larvae to the third
instar and transferring known numbers to plants one day before applying the test
insecticide .
Experimental Design:—For the initial tests, groups of four or more pots
of plants containing a total of 50 or more larvae in each age group should be
treated as a unit for each dosage level and within the range of greenhouse
temperatures required for production of the crop involved. Three or more
replications per treatment are desirable for evaluation of results.
Include untreated control and a treatment with test chemical of known
performance such as carbaryl as a standard for effectiveness.
Application and Equipment:—Sprays should be utilized for control of
localized infestations of these pests. Knapsack sprayers operating at 2.1-4.2
kg/cm2 (30-60 psi) and delivering 187.1-935.4 liters/ha (20-100 gallons/acre)
are satisfactory for the preliminary tests on groups of infested plants: also
for treating groups of 20-30 tomato or cucumber plants or comparable areas of
lettuce in growing crops. For application of thermal, mechanical or gas
propelled aerosols or fumigants, individual compartments with volumes of 28.3
m^ (1000 ft. ) or more would be required. For these tests, which would precede
treatments in larger greenhouses, groups of plants infested as for preliminary
spray tests could be placed throughout the compartment to provide infestations
for mortality counts.
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All tests should be conducted within temperature range required for
growth of the crop and at time of day or night when host plant injury might
be critical due to closing of ventilators.
Since sick caterpillars usually drop from treated plants, sheets of poly-
ethylene or other material should be placed on the soil or mulched surface around
the plants before applying the test chemical.
Sampling:—Make direct counts of 50 or more larvae from each replicate
(Lindquist 1972, Harris et al. 1975) in preliminary tests. Select the time of
recording mortality according to speed of action of the test chemical. Usually
the counts can be made in 24 "or 48 hour posttreatment.
Make insect injury ratings of 1-5 or 1-10 on host plants and carefully
describe leaf damage such as percentage of leaf area destroyed or market
acceptability for each category. Record number of injured and uninjured fruits
in treated and check plots.
Take yield records of treated and untreated plots and take note of the
extent of feeding injury to marketable parts of the plants.
Record host plant injury following application of test material, including
foliage injury such as chlorosis, marginal burn, and also flower bud
abscission on tomatoes and cucumbers.
Analysis and Reporting of Data:—See statement under Leafminers.
References
Hairis, C.R., H.J. Svec, S.A. Turnbull, and W.W. Sans. 1975. Laboratory
and field studies on the effectiveness of some insecticides in controlling
the armyworm. J. Econ. Entomol. 68:513-16.
Lindquist, R.K. 1972. Bac-illus tnur-ingi.ens'ls formulations for cabbage looper
control on greenhouse lettuce. Greenhouse Veg. Res.: Res. Swnrn. 58.
OARDC, Wooster, Ohio.
Smith, F.F. 1959. Control of Insects of Greenhouse Vegetables. USDA
Agric. Handbook #142. 25 pp.
Slugs and Snails
Several species of slugs feed on foliage of many greenhouse plants including
young tomatoes, cucumber, lettuce, radish, and cress. Their injury is recog-
nized by the ragged appearance of the foliage, gouged tomato fruits, and the
presence of slime tracks. The most common species are the gray garden slug,
Deroceros reticulatwn (Muller), gray field slug, D. laeve (Fuller), and the
spotted garden slug, Limax maximus (Linne). Slugs frequent damp places and
especially under boards, flower pots, or under any debris. Sanitation to remove
their hiding places is important in reducing populations.
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lone f6 °f metaldenyde baits and dusts or sprays containing metaldehyde are
slugs a lng contro1 practices (Smith 1959). Metaldehyde is more toxic to
effect^h3 C°ntact P°is°n than as a stomach poison and exerts a greater lethal
Also mr^H^ material ls applied to surfaces that are traversed by the slugs,
ha-ifl fv a!dehyde in dusts or sprays has been more generally effective than in
baits (Howitt and Cole 1962).
re-
Weather conditions at time of treatment and following treatment affect
suits. Low dosages of the toxicant, metaldehyde, that immobilizes slugs and
causes excessive slime production and results in desiccation during a period of
low_humidity will be more effective than high dosages applied during rainy
periods and high humidity (Howitt and Cole 1962). Effectiveness of baits"
containing mesurol is influenced less by weather (Getzin 1965).
Discrepancies have occurred in the assessment of efficacy of candidate mol-
luscicides by various workers using different techniques, different test species
and with different objectives (Judge 1969). Laboratory bioassays can give only
an indication of which materials should be subjected to the more realistic
rigors of field evaluation (Judge 1969).
Effectiveness of a given bait is governed by the quantity consumed before
paralysis sets in, there being a balance between a concentration which would
produce a sublethal dose and that which would be repellent (Cole 1967).
Increasing the attractiveness of a bait as by addition of beer also increases
its effectiveness. Longer lasting baits by use of inert plastic foam instead
of the conventional milled wheat bran are also indicated (Smith and Boswell
1970).
Crop and Location:—For the preliminary tests with baits to determine toxi-
city of a chemical to slugs, mix the chemical with a bait and present this bait
to the animal either in the laboratory or in the plots of the growing crop. The
results depend on toxicity of the chemical, on the palatability of the bait
mixture, and on the feeding activity of the test animal.
The technique involving the direct introduction of a poison into the slug's
alimentary canal provides a method for determining the LD 50 of any given
chemical (Hunter and Johnson 1970). However, such chemicals may be of no
value as a molluscicide unless it can be incorporated into an attractive bait.
Attractiveness of bran in baits has been long recognized but not fully under-
stood (Judge 1972). Attractiveness of bran is short-lived because of molds
(Getzin 1965) . Use of inert carriers such as plastic foam soaked in the toxicant
and an attractant such as beer may lead to longer lasting slug baits (Smith
and Boswell 1970) .
Granular formulations or sprays containing candidate molluscicides
should be distributed over flats of young peas and 20 adult D. reticulation or
other test species caged on each flat. Dead and living slugs and damaged
pea plants should be counted at the end of one week (Judge 1972). A candidate
bait in a petri dish can also be tested in a flat of caged'peas or other suitable
host (Smith and Boswell 1970). Crowell (1967) employed wooden boxes 45.7 x
24.2 x 8.9 cm (18 x 9.5 x 3.5 in.) with covered refuge and open arena for
laboratory testing of candidate molluscicides.
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Field tests may be conducted on a sod field where slug populations are
uniformly distributed. The area should be divided into plots approximately
5 m (16.4 ft.) wide and 15 m (49.2 ft) long and separated from contiguous
plots by a cultivated strip 1 m (3.28 ft.) wide to prevent slug migration.
The treatments should be arranged in a randomized block design and with 4
replications. Granules can be applied broadcast with standard equipment
(Judge 1972). Molluscicide baits can be applied at 1 to 5 m (3.28 to 16.4
ft.) intervals in similar plots. Results of efficiency are determined by
placing four or more 30 cm (1 ft.) square boards on the soil at intervals
in each plot and making weekly counts of slugs that congregate beneath.
Greenhouse plots of tomatoes, cucumbers, lettuce, radishes, or cress
should be arranged for testing the most appropriate molluscicide formulations
resulting from the program outlined above.
Experimental Design:—Slugs may be collected from the infested crop
area or reared in laboratory cultures (Judge 1969) . Include from 5 to 20
slugs for each material and dosage rate in each series of tests that should be
replicated 4 or more times.
Each series of tests should include (a) a known effective treatment as a
standard and (b) no treatment.
Application and Equipment:—Granular baits can be distributed on the soil
surface by hand. Sprays can be applied with hand-pumped compressed air
sprayers operating at 2.1-4.2 kg/cm (30-60 psi) or commercial equipment
adaptable for this use.
Greenhouse compartments or plots in the commercial growing crop that are
at least 5 m (16.2 ft.) square should be used for greenhouse tests of baits,
granules, or ground sprays.
Avoid applications to the growing crop.
Sampling:—Make counts of dead and living slugs in the areas near bait
stations.
Make weekly or semi-weekly counts of living slugs that congregate under
30 cm (1 ft.) square boards placed 4 per plot beginning with a pretreatment
count. This method can be used in tests with baits or ground treatments with
granules, dusts, or sprays.
If damage has been allowed to progress in the test plots, record number
and weight of damaged tomato fruits and rate foliage iniurv on cucumber, radish.
cress, and lettuce plants as per cent loss from slug feeding.
Analysis and Reporting of Data:—See statement under Leafminers.
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Beferences
Crowell ft u n QA-?
' • • J.yb/. Slug and snail control with experimental poison baits.
J- Econ. Entomol. 60:1048-50.
Getzin, L.W iqp,q n -i
f ' , ' Control of the gray garden slug with bait formulations
carbamate molluscicide. J. Econ. Entomol. 58:158-59.
Howxtt A J and S.G. Cole. 1962. Chemical control of slugs affecting
55-320-258 and strawberries in the Pacific Northwest. J. Econ. Entomol.
Hunter, P.J., and D.L. Johnston. 1970. Screening carbamates for toxicity
against slugs. J. Econ. Entomol. 63:305-06.
Judge, F.D. 1969. Preliminary screening of candidate molluscicides.
J. Econ. Entomol. 62:1393-97.
Judge, F.D., and R.J. Ruhr. 1972. Laboratory and field screening of granular
formulations of candidate molluscicides. J. Econ. Entomol. 65:242-55.
Smith, F.F. 1959. Control of Insect Pests of Greenhouse Vegetables.
USDA Agric. Handbook #142. 25 pp.
Smith, F.F., and A.L. Boswell. 1970. New baits and attractants for slugs.
J. Econ. Entomol. 63:1919-22.
Spider Mites
In northern greenhouses the two-spotted spider mite, Tetranychus urticae
Koch, is most common; but the carmine spider mite, T. cinnabarinus (Boisduval) ,
may also be involved. The latter is a southern species that is often
transported on plants shipped to northern growers.
These mites cause severe stippling injury, bronzing, drying of foliage,
and extensive webbing over the entire plant. Thousands of mites in search of
food may accumulate on tips of shoots, plant stakes, or hang in festoons of
webs from the foliage.
Spider mite infestations are more severe during spring and summer seasons
when temperatures are higher. A generation may be completed in 9 days in summer:
but, at lower temperatures of fall and winter, from 12 to 16 days or longer
are required. The developmental stages of spider mites consist of eggs (5 days),
6-legged protonymphs (3 days) , quiescent (2-3 days), 8-legged deutonymphs (3
days) , quiescent (2-3 days), and adults which may live and lay eggs for 2 to
4 weeks. Most acaricides act against only the active stages - protonymphs,
deutonymphs,' and adults—and require several applications at regular intervals
to reduce the population. So-called ovicides may be more strictly interpreted
as larvicides or prenatal ovicides (Henneberry et al. 1961).
Tepp, sulfotepp, malathion, dichlorvos, and parathion in aerosols are
effective against the active stages. Parathion is the most effective because
of its residual action, and less frequent applications are required. Two appli-
cations of parathion at 7 to 10 day intervals are effective. Several weekly
applications of the other materials may be necessary.
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Spider mite strains vary widely in their susceptibility to acaricides
(Smith and Fulton 1951, Taylor and Smith 1956, Henneberry et al. 1961).
The level of resistance in the mite strain used in testing candidate
acaricides may be evaluated by leaf dip or slide dip methods (Walker et al.
1973).
Crop and Location:—For preliminary tests to determine levels of resis-
tance in the test strain, lima beans in 10 cm (4 inch) pots are satisfactory
host plants.
Tomato or cucumber plants are grown in pots or containers and infested
with mites by pinning leaf pieces from the test colony on 2 or more leaves of
each test plant.
Experimental Design:—Susceptibility or resistance of an unknown mite
strain may be determined by dipping infested beans in primary leaf stage and
held in bottles of nutrient solution. Include 4 replicates per treatment and
100 or more mites with each concentration of test chemical (Walker et al. 1973).
Ovicides should be tested against eggs and adult females as outlined by
Henneberry et al. (1961).
Groups of 4 or more tomato or cucumber plants grown in pots and infested
with mites by pinning on leaves from the test colony for use in sprays applied
with a knapsack sprayer or for spacing among other plants in greenhouse units
28.3m (1000 ft. ) or larger houses for testing aerosols, mists, and
combustible powders.
Each formulation should be compared with a standard formulation of
known performance and with untreated check.
See Leafminers for other details.
After the minimum effective treatment has been determined, make a
series of scheduled applications in commercial greenhouses to determine
efficiency of control and effect on crop.
Application and Equipment:—See statement under Leafminers.
Sampling:—In preliminary tests involving beans with primary leaves,
make 24 hour posttreatment count of adult females and immature mites on
treated and untreated leaves. Mites that drop from plants, after treatment
with some chemicals, should be recorded from papers placed beneath treated
plants.
Mortality of spider mites on infested tomato or cucumber plants can be
determined by examining leaflets or leaf discs cut with leaf punch or cork borer.
Each sample should include 10 leaf discs or comparable number of leaflets
taken at random from each replicate that involves 100 to 500 mites. The first
sample should be taken 24 hours posttreatment. Later samples at 3, 5 and 7
days posttreatment may be necessary to determine residual activity of test com-
pound. In houses receiving a series of treatments, make weekly samplings of
discs or leaves to determine decline of mite population compared to untreated
checks.
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posttre mite lnjury ratings of 1-5 on cucumber or tomato at 1 and 7 days
with atment' Fully describe each category in rating scheme and compare
Pr
plant Pi°?ress of in:iury on untreated plants. Make periodic evaluations of
of cjrh^V^ m mite feedinS and phytotoxicity in houses receiving a series
or scneduled treatments.
Analysis _and_JRgEorting_of Data: -See statement under Leaf miners .
References
Henneberry, T.J., E.A. Taylor, and A.L. Boswell. 1961. The effect of Tedion
on the eggs and larvae of three strains of the two-spotted spider mite,
Tetranyohus telanus. J. Eoon. Fntomol. 54:168-9.
Taylor, E.A., and F.F. Smith. 1956. Transmission of resistance between strains
of two-spotted spider mites. J. Eoon. Entomol. 49:858-9.
Walker, W.F. , A.L. Boswell, and F.F. Smith. 1973. Resistance of spider mites
to acaricides: Comparison of slide dip and leaf dip methods. J. Econ.
Entomol. 66(2) :549-50.
Smith, F.F., and R.A. Fulton. 1951. Two-spotted spider mite resistant to
aerosols. J. Eoon. Entomol. 44(2) : 229-33.
Tomato Pinworm
The tomato pinworm, Ke-ifeTia lycopevs'icella (Busck) , has a long history of
sporadically infesting greenhouse tomatoes in northern states and is a regular
pest on greenhouse tomatoes as well as field grown tomatoes in warmer parts of
the country.
The tomato pinworm does not survive out-of-doors in northern states but
infests field grown tomatoes near greenhouses where infestations persist from
year to year. It is transported to new areas on infested tomato plants or in
fruits or in used containers.
Larvae make blotch mines in leaves, feed in growing tips and flower buds,
and enter the fruit through pinholes under the calyx of ripening fruit.
Effective control efforts should be directed toward the insect before it invades
the fruit where it is not only invulnerable to insecticide applications but
causes the greatest damage to the tomato crop.
Crop and Location;—Select a variety of tomato commonly grown in commercial
greenhouses. Plants should be grown in containers and under isolation to prevent
unwanted infestation with pinworms or other insects.
Less desirable, for preliminary tests, is the selection of plots in infested
greenhouses where active flying adults can reinfest treated as well as untreated
plants.
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Experimental Design:—Groups of plants infested with 50-100 or more insects
for each treatment should be replicated three or more times. Each series of
tests should include comparable groups of plants that receive (a) a known
effective treatment as standard and (b) no treatment. Treated and untreated
groups of plants should be isolated to prevent post-treatment reinfestation.
Application and Equipment:—Expose plants for one to two days to egg-laying
adults in a cage or greenhouse compartment that contains infested plants.
Application of the test materials should be made to groups of plants prior
to egg hatching to determine their potential for destroying larvae before they
penetrate the leaves or fruit. Residual action of test materials in sprays,
dusts, aerosols and some fumigants might be effective.
To test the effect of materials against larvae within leaf mines, make
application to plants (1) when the larvae are in their early instars and the
mines are small and (2) against more mature larvae when mines are larger.
Insecticides in sprays, dusts, aerosols and fumigants may penetrate the thin
plant tissue over the larvae.
To test the materials against adults, suspend screen cages in duplicate,
each containing 5 to 10 moths, in greenhouses prior to treatment with test
fumigants, aerosols or dusts.
After specific action of test chemical has been determined as above,
series of treatments at timed intervals can be made to plots or preferably
entire sections of commercial greenhouses.
In all tests, include comparable untreated check plants or plots and a
known standard chemical treatment as a basis for comparing efficiency of test
material.
Sampling:—Against hatching larvae on treated plants, make observations
on mines that develop indicating larvae that survived the treatment. Make direct
counts of older larvae in mines or adults in cages one day after treatment and
7 days after treatment.
In tests conducted on the growing crop in commercial greenhouses where
2 to 8 or more weekly applications may be made, (a) records can be made on
dead larvae in mines, (b) mines per leaf on treated plants, and (c) fruits with
pinworm injuries (Lindquist 1975). Similar records should be made on
replicated, untreated plots.
Analysis and Reporting of Data:—See statement under Leafminers.
References
Anderson, L.D., and E.G. Walker. 1944. Tomato pinworm control in the greenhouse
J. Econ. Entomol. 37:264-68.
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Lindquist, R.K. 1975. Insecticides and insecticide combinations for control of
tomato pinworm larvae on greenhouse- tomatoes: A progress report.
Greenhouse Veg. Res.: Pes. Swnrn. 82. OARDC, Wooster, Ohio.
Neiswander, R.B. 1950. The tomato pinworm. Ohio Agric. Exp. Sta. Pes.
Bull. 702.
Thomas, C.A. 1932. The tomato pinworm Gnorimoschema lycopersicella (Busck) ,
a new pest in Pennsylvania. J. Econ. Entomol. 25:137-8.
Thomas, C.A. 1936. Status of the tomato pinworm Gnorimo^schema lycopersicella
(Busck) in Pennsylvania. J. Econ. Entomol. 29:313-17.
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