AE PLANT7 BOAR,*
United States Department of Agriculture .. Agricultural Research Administration Bureau of Entomology and Plant Quarantine
MERIMENTS WITH DDT FOR CONTROL OF INSECTS ATTACKING
CEREAL AND YORAGE CROPS IN THE FIELD AID IN STORAGE
Compiled by C. M. Packard
Division of Cereal and Forage Insect Investigatioxs
Experiments conducted with DDT (1-trichloro-2,2-bis(p-chlorophenyl)
ethane) during 1944 for the control of various insects that attack
cereal and forage crops in the field, and grains, seeds, and milled
cereal products in storage, are briefly summarized in this paper. In
considering these results it should be clearly understood that no
recommendations are being made for the practical use of DD on any of
these crops or against any of these insects. Many questions remain unanswered relative to best mixtures or solutions to use, dosages to apply, application schedules, residue 'hazards, effects on Beneficial inscts, and results when used under conditions different from those
prevailing in this years experiments. Further investigations are
necessary in order to obtain the answers to these questions.
In field trials by J. R. Parker, E. J. Hinman, and C. C. Wilson,
various.concentrations and dosages of DDT in pyrophyllitewere applied
as dusts to alfalfa and range grasses in Arizona, California, and
Wyoming. he results indicated that very high mortality of grasshoppers, including Melanolus mexicanus (Sauss.), M. bivitattus (Say),
Sfemur-rubrum (Deg.), and Camnula pellucida (Scudd.), can be obtained
from a single treatment with 15 to 20 pounds per acre of dusts containing 15 to 20 percent of DDT. Good control was also obtained with sprays made from a dust containing 10 percent of DDT in pyrophyllite mixed with water to give 0.36 to 0.48 percent of DDT. The results of very limited
trials of an aerosol containing 3 percent of DDT and 1.5 percent of
pyrethrum extract were inconclusive.
Fair to good mortality of grasshoppers was obtained by Mr. Wilson
from a single application, at the rate of about 20 pounds per acre, of a bait mixture containing the following proportions: 3 pounds of powdered technical DDT, 100 pounds of wheat bran, 1 gallon of molasses,
and 1-1/2 gallons of water.
In field tests conducted by.P. Luginbill and C. Benton near
Lafayette, Ind., barrier lines of dust containing 5 percent or more of 'DDT in pyrophyllite, applied at the rate of about 1 pound per rod, gave excellent protection of corn from immature chinch bugs (Blissus leucopterus (Say)) migrating to it 'on foot from adjacent wheat. The dust did not act as a repellent or prevent some of the bugs from reaching the corn, but it killed them.before they were able to injure the corn materially. Dusts containing lower percentages of DDT were not tested but may be found effective.
Heavy applications of dusts containing 1 to 5 percent of DT in pyrophyllite directly to the infested portions of the corn plants and the surface of the soil close to them gave excellent control of the bugs without discernible injury to the plants.
LIygus Bugs Attacking Seed Alfalfa
In control experiments with Lygus spp. conducted by F.V. Lieberman on seed alfalfa at Gandy, Utah, one application of a pyrophyllite dust containing 10 percent of DDT at 271 pounds per acre of the dust produced 135 to 725 pounds of thresher-run seed per acre, with an average of 429 pounds as compared with practically complete loss of the seed crqp in undusted areas. The seed matured earlier in the LDDT-treated plots and was riper and cleaner than that produced in plots treated with other insecticides. Owing to an early frost, seed from most of the plots treated with other insecticides was badly blackened and all seed in them that might have matured in the cocks wag shriveled. The results were affected, however, by uneven soil moisture in the various plots and the abnormally early frost, so.that the comparative effectiveness of the different treatments could hot be closely evaluated he DDlT asapplied during the pre-bloom stage after the buds had formed but before many flowers had opened, in order to avoid killing wild bees essential to pollination. No domestic bees were present in the area.
So far as could be observed the DDT had no repellent effect on, and caused no mortality of, the wild bees. *The experiments indicated the possibility*that lDDT can be used without appreciable harm to domestic or wild bees.provided application during the main blooming period is avoided, but further observations are necessary for the settlement of this questions Large aphid and thrips populations in the treated plots were virtually eliminated. Other insects, such as coccinellid beetles and larvae, nabid nymphs and adults, grasshoppers, flies, and lepidopterous larvae, were killed. The highly migratory species constantly reinfested the plots, but their numbers were usually less in DDT-treated than in untreated plots, indicating that this insecticide has a lasting residual effect.
ts eaz Orge~~Xy an ayton, Ore., indicted
DDT o b~vey pomiingffor the control of t'h~e vetch~ bruchid(Bucu
'brchili.Faraes)attacking hairy vetch seed. L. P. Rocwo n
W.M R632e fondthat oni hair vetch two applications of a&utcn TI 5,percet of DDT nyyrphyllit-eg at rates of 22 to 25.pud
Vf he ustperacq eas the 3pods began to s~et and 15 days later, av
.. *Plqnt ~otr62l -of tevtch bruchid without -isible injury toth
ffi ts- wer sgictly better than two applications of a dust dont~ain~n 1 ecntoot Oenone~ at appr'oximat~ely the same rates per
TheDDTreaied effective much longer than the rotenone, and
it seeed prbbe that three or four applicat ions of the latter would
IiWre een'neessryto equal two appications of the DlDT in effectiveq~~ti;-* inl application of a dust containing 3 percent of DDT in Pyrp~ylit,, t the rate of 22 to 25 pounds per acre applied 10 days
too-ate or bst esults on 5 acres- of hairy vetch at Dayton gave
commrcilyproitable although not full control. The seasons
-r~sltsindcat tht one well-timed application of 3 percent DDPT dust
'4'5,t ,5 Pquds eracre- may give ad-equate control of the vetch
: kachd..Sevralother species of-insects, including cootineflld
:bi~tle -were Idle y the DDT, and also by the rotenone dust and 'by
e~t~seica bat spaytat was 'being tested. Very fewv aphids and
00'$M~dbrcoconeli larvae apered to have been afete.N
b'4, er fondno coldan decrease be noted in th numer of
livt hon ee wpt from the dusted plots. Bees may be an aid to
ollnaipn of bairy yetch, however, and more conclusive obsermaaenecesar to determine what effect the application of DDT to
Yelvetbean Cat erpill~ar
Sxgllet'ontroI of the velvetbean caterpillar (Anticarsia
gematiis Rbn))on peanuts and soybeans yas obtained byZ, 0 Youn,
Of his,3ueau an L M.Eglish, of the Alabama State Agrcutural
-Pawitm Sttio,, n feldtests with single applications of DD
4uss ad sray. Adus containing 3 percent of DDT in pyropyllite
I-Waeffcti an th reult indica.ted that moere dilute dusts might
so~~~~ besteawoy either information is needed to 4.etcrmi.ne the
_15qt ustan spay repraions and dosages to apply for control of
thisinsct. Mre oun oberve that~ the residue Qf Aevera'l application ot cocentate MT pra, obtained by miixi~g 10O percent DT P Yo~hllie ustin ate c nnng a sml percentgeof apr.aer
to panis i Juy.1-or ontolpf the white-fringed beetle, was~efe
tiv aaint n ifetatonbythe veletbeeji catrpllar which dev1l
Potato Leafhopper on Alfalfa and Peanuts
At Beltsville, Md., F. W. Poos obtained. a great reduction in numbers of the potato leafhopper (Empoasca fabae (Barr.)) on alfalfa and peanits by two-applications 9 days.apart ofa dust containing percent of DDT in pyrophyllite, or of a spray consisting of a mixture of 0.66 percent of DDT in dust form with water, with a spreaderadded.' Material increase in yield and quality of hay was obtained in the treated alfalfaplots. Two applications 16 days apart of the sam spray and dust to peanuts resulted'in great reduction ofthe leafhop per population but no increase in yield because of severe leaf spot infection on both treated and untreated plots late in the season
Tobacco Thrips on Peanuts
Observations and experiments by F. W. Poos, at Beltsville, W have indicated that. the tobacco -thrips (Frankliniella fus~ca (His) is the chief cause.of-the widespread injury to young peanut plants commonly known as pouts. In an effort to determine primarily how much effect this injury has on yields, seven applications of 2per cent DDT-pyrophyllite dust were made at 3- t $-day intervals 'o
p wee. at3- to 9-day intervalston
series of plots, 8 applications at, 4- to 6-day intervals of a-spray containing 0.66 percent of DDT, obtained by mixing a 10 percent DTpyrophyllite dust with water and a small percentage of spreader, to another series, and 8 applications-at 4- to 6-day intervals-of a aerosol containing 10 percent of DDT to a third series. Good control of the thrips and decided increases in yield resulted from all these treatments, with no evidence of injury to the plants.
European Corn Borer in Sweet Corn
Following favorable results'from preliminary trials of DDT by
2. D. Questel in 1943 for the control of the European cornborer
(Pyrasta nubilalis (Hbn.)) in sweet corn, experiments were continued in 1944 near Toledo, Ohio. In field-plot tests conducted by 0. Batchelder, in which different strengths and dosages f DDT in p lite were applied with ground equipment, borer re'duc tions of 72 to 9 percent were obtained by four applications at 5-to' 7-day intervals dusts containing 3 to 6 percent of DDT, at 1.2 to .2.4 pounds of II)T acre-application. Your aerial applications at 3- to 5-day intervals of a dust mixture of 3.75 percent DDT in pyrophyllite, at approximate 1.5 pounds of DDT per acre-application, gave borer reductions of 74 percent in the plants and 82 percent in the ears. Excellent control was obtained on the sweet corn variety Evergreen from four aerial applications at 3- to 5-day intervals of a concetrated spray contain ing 8.9 percent of DDT dissolved in a horticultural oil, at the rate about 2 pounds of DDT per acre-application.
.. . .. . .
Three applications at 5-day intervals of sprays containing
approximately 0.05 percent of DDT were made by Mr. Questel in another series of plets, at the rate of 0.76 pound of DDT per acre-application. These sprays were made by mixing a pyrophyllite dust containing 10 percent of DDT with water and a small percentage of spreader. The treatments resulted in 92 to 95 percent reductions in numbers of borers in the plants as compared with the populations in check areas.
Corn Earworm in Sweet and Seed Corn
Injection of white mineral oil containing 1 percent or more of DDT into the silks of sweet corft ears produced 85 to 99 percent of worm-free ears, in experiments conducted by J. W>ilcex, of the Division of Truck Crop and Garden Insect Investigations in southern California fields heavily infested with the corn earworm (Heliothis armigera (Hbn.))
A variety of oil solutions and emulsions of DDT in concentrations of 0.5 to 2 percent were tested by R. A. Blanchard in Illinois on ears of'veet corn and on dent corn grown for seed, by injection into the silks and atomization on them, for the control of the earworm. From 91 to 100 percent of worm-free ears were obtained by either injection or atomisation of 2 percent of DDT in undiluted white mineral oil. Various degrees of control were obtaifted with the different emulsions. The rests indiate that one may-be found that will give hiEgh_ -protection from the earworm when it is atomized on the ears, at compratively low cost and withano injury to the ears or plants.
Corn Flea Beetle
Good protection of young sweet corn from the corn flea beetle
(Chaetognema'pulicaria Melsh.) and considerable reduction in the bacterial wilt which it transmits were obtained in experimental plots of a wiltsusceptible and a wilt-resistant variety conducted by F. W. Foos at Beltsville, Md. Following 5 applications of 0.66 percent DDT spray, obtained by adding 10 percent DDT-pyrophyllite dust to water containing a small percentage of spreader, at intervals of 3 to 6 days, onl" 2 beetles were found n a treated row rf corn as compared with 128 An an untreated row., In the susceptible variety a much better stand was maintained-in the treated rows than in the untreated rows.
The high effectiveness DB obtained in arejiminary tests by
H. C. Young and staff during 1943, both as a stomach and'a contact poison for the white-fringed beetle (Pantomorus leucoloma.(Boh.)), was sibstantiated by various experiments carried:on by them at Florala, Ala., in 1944. In these tests a.-dust containing-10 percent of DDT in pyrophylite was used in the prcparation of all dusts, sprays, and soil treatments.
Sprays containing 1/8 pound or more of DDT and 0.1 ound of a
wetting agent per 100 gallons of water, applied to peanut and chrysanthemum foliage as a stomach poison, gave mortalities of adult beetles in excess of 90 percent, and were as effective-as a spray containing pounds of synthetic cryolite (approximately 9C, sodium fluoaluinate) and 0.1, pound of wetting agent per 100 gallons of water. Sprays con training 1/2 pound of DT in dust form per 100 gallons of water with wetting agent gave an average mortality of 93 percent-of adults when applied as a contact poison.
lDDT dusts applied as a contact poison against the adults of the white-fringed beetle showed that lighter-dosages gave greater mortalities when applied to the surface of the soil on which the beetles crawie than when applied to the beetles themselves. Heavier dosages were mor effective when applied to the beetles. Pyrophyllite dust containing 5 percent of DDT applied to-the beetles and on the soil at the rate of
0.774 pound of 2DT per acre gave 89.percent mortality. The fact that DDT applied to the surface of the soil is effective as a contact'poisod against the adults is considered the most important finding of the season.
D T dusts applied to the foliage remained effective against adults for,about 5 days or until' 0.25 to 0.50 inch of rain had fallen. Whe rain fell, the dusts gave fair mortality for more than 5 days. A de spray containing 0.2 pound of DDT, 2 pints of fish oil, and 0.1 poubt of a-wetting agent per 100 gallons of water remained effective for about days. A concentrated spray containing 4 pounds of)DfT,'20 pitts af-fish oil, and 1.14 pounds of a wetting agent per 100 gallons of water gvea average mortality of 66 percent af-eri 10 days' exposure and 5.07-inches of rain, and 56 percent after 15 days' exposure.and 7.95 inches of rai
When mixed with the top 3 inches of soil, DDT at 50 and 100 pound per acre caused mortalities of 34 and 65 percent of the adults, .respe tiv.ely, by the end of 7 days, in field cages cont ainig otted ch~a themu plants in untreated- soil as foodd'
In laboratory tests DlT applied .to soil 'atratos of 25 'to 25
pounds.per acre gave mortalities bf larvae 'in-the soil of from8.5 to 100 percent. .It was more effectiv-e against half-grown thigag4inst lager larvae. Lead arsenate similarly tested at the rate of 1,000 pounds per acre did not cause any mortality, while DDT at 50 pounds :er- a cre:gave 95 percent mortality of. half-grown larvae during the' 30-day test.-period.
In small salve-b.ox tests of baits against three-fourths grown
larvae in moist sterile soil, peanut meal containing 10 percent of DDT caused 50 percent mortality in 15 days, while ground whole peanuts containing 1 and 5 percent of DT caused 95 and 100 percent mprtality,, respectively, in 15 ays.
DDT'used in a water suspensio did not kill the' eggs of the whit efringed beetle, but when dissolve in kerosene at rate of -1,6 to.6,W grams per 100 ml. it was an effective ovicide.
ii s gownin oir- containing 250 pounds of MT per ace,
thoougly ashd, ndthen fed to three-fourths grown'larvae case
Germnaton f cotton, corn, peanut, oat, and cov,.pea seeds. was
not ff~tedby reaingthem with a dust containing 50 percent of
DM n-propyllte before planting. Austrian -:,ihter'-peas, peanuts,
V~ie,.swbtpoato.white potato, cotton, corn, co-upea, soybean, radisW, an& lue upieha ve been groim in soil treated wi~th various closages -of
T u t-,t,1 ounds per acre, aiid in the case of some of theses rops
,p to 0- uds per acre, without visible injury. On the other hand, 44=7 o~youg~rye pnts, consisting of reddening of foliage, twistingo leve, poor grovtli, and d~iing of some plants, occurred in pot
and'feld-potteszts in which DDT was used as a soil insecticide at
,/:~its'f 1 t 250 pounds of DOT per acre in dust or emulsified form.
b 33) pa @pplodas an emulsion the injury pvas very pronounced.
Oveh ~ atth m&pun dosage. The injur'sr caused by the dust treatmets
was~sligty th 10-pound dosage but increased with the dosage.
Lare-salefield trials of DDT in a 2.5-percent &tstv a concen...'.trte,;pryan a dilute sprayr were conducted in cooperation wvth
4hewhte,-!rned beetle control unit of the Division of Domestic Plant
qxwanine. uin pover ground, equipment and an air'l1ixe; These
3ff-tv0as-s tlxer dts, but the complete
,rimls wllno be available until populationi of their larval progeny -Antretedandcheck areas can be determined during the spring of 19145,
I-nsqcts Attacking Stored Seeds, Grain, and MAilled Cereals
Mxues of DD with seeds to protect them from insect inf~estation
whlei storage have been tested on a laboratory scale at MLanhattan,
Epne, y J 0. F'raxikenfeld and R. T. Cot-ton, They found that as little
..-s 005 rent by~ weight of a-oyrophyllito dust containing 3,,percent
IMTor 5 prtsof DLT per million ,',mixed with iTheat, seed' cbnttining 122
and-16perent .of moisture was highly~ effective in' protecting the
Whet fom hecommo insect pests of stored grain. Wheat seed mixed
wit asmuc as0.2 percent by weight of undiluted technical DDT showed
'nolos ofgermnation at the end of )4 months, Seed of corn, lettuce, tomao, ad watermeloni in 1 to 16-ounce paper packages, and bulk sunA flwer ee& in cotton cloth bags, mixed -Ath 0.05 Dercent by weight of
uniued DD-and exposed to heavy infestation for 2 months Inth
laortoyand ~in a seed warehouse, remained practically uninfest$d by fnot 'of'einsects that commonlly in-fest stored seed, *hile'umtreate&
-6hoksbea havily infest~ed. Cadelle and dermostid latvde were ...~~ieal more resistant tha the other insects rre8 nt, .
Zartwightalso reported practically no control of dermestid larvae in
drywhet eed heavily treated -ith ZD dust at Lafayette, Ind.
DDT is one of the most efficient materials yet tested by Cotton and Frankenfeld for making paper or fabric bags and cardboard cartons of cereal products immune to insect attack. Paper bags or wrappers that had been immersed in a 10-percent solution of DDT in acetoneor 6ther solvent and dried apparently gave complete protection of the contents and were not cut through by the cadelle or other species wh ordinarily penetrate almost any type of wrapping, Cotton cloth bags sprayed with or dipped in a 5-percent solution of ~DT in carbon ttachloride, dried, and filled with fl-our, were remarkaly repellent to insects. Paper or cardboard wrappings coated with varnish containing 5 percent'of DDT were also-resistant to insect attack. -DDT can also b applied in sizing or coating liquors, and there appear to be many possibilities for its use as a repellent in package materials.
Tests in Kansas by Dr. Cotton, H. H. Walkden, and assistants of a refined odorless kerosene containing 5 or 6 percent of DDlT sprayed on the interior walls and woodwork of .emty farm grain bins, flour and. seed storage rooms, and one story of a flour mill gave excellent control of cadelle, flour beetle, and silverfish infestations. In one empty farm bin approximately 8,000 dead cadelles were swept from the floor at the base of 10 linear feet of sprayed wall. For weeks after the treatment cadelles emerged from the walls and died. The cadelle burrows into the woodwork and walls of farm bins and literally hone, combs them. Many species of grain-infesting insects hide in these burrows and emerge to attack the new grain when it is placed in storage The resulting damage to farm-stored grains amounts to millions of dollars annually. Milled cereal products in infested box cars or in storage in warehouses are similarly invaded by the cadelle, which will cut through almost any type of bag or container to reach the products within them, and thus permit the entry of other insects as well. the DeT-oil spray appears to offer the best means yet discovered of destroy ing insect infestations in woodwork of bins, storage rooms, warehouse, mills, and box cars.
Preliminary tests in southern Louisiana during the fall of 19 by J. W. Ingram and assistants indicated that DDT was not.so effective as undiluted cryolite in controlling the sugarcane borer (Diatraea saccharalis (F.)). These results were substantiated by further trials on field plots in Louisiana in 1944. Four weekly applications of an undiluted synthetic cryolite dust and an undiluted natural cryolite dust, both containing approximately 90 percent of sodium fluoaluinate, and a dust containing 10 percent of DDT in pryophyllite were made against first-generation borers in young cane, at the rate of pounds per acre-application. These insecticides gave borer reductions of 91 to 85 percent, 65 to so percent, and 11 to 34 percent, respectively, as compared with borer populations in untreated check plots. When the sam insecticides were similarly applied at.the rate of-10 pounds per acr during midsummer on larger cane against second-generation borers, synth and natural cryolite gave reductions in joints bored of 61 and 50 perce respectively, whereas the DDT plots had 18 percent more joints bored th the untreated check plots. Why DDT is so much less effective against this borer in cane than it is against the European corn borer in corn, since the two species have similar habits, is not apparent.
Yellow Sugarcane Aphid
In a replicated experiment conducted in Louisiana by Mr. Ingram a sistants in the fall of 1943, the number of leaves infested by low sugarcane aphid (Sipha flava Yorbes) was six times as great plots treated with DDT as in untreated plots, and more than t s great as in plots treated with synthetic cryolite (approxim 90 percent sodium fluoaluminate). There was very little injury s aphid in the 1944 experiments against the first-generation borer, but in the experiment against the second-generation the aphid infestation was considerably greater in the plots t id th IDT than in those treated with cryolite or untreated.
a single test by P. Luginbill at Lafayette, Ind., a dust cont5 percent of DDT was applied to the soil in a cage at the rate o 2 pouds of DDT per acre and washed in with a copious sprinkling
ter. This treatment had no effect on the white grubs (Phyllophaga ) that had been placed in the soil. Young corn plants that were t inches tall when the DDT was applied wero visibly affected. All h appeared sickly and the tips of the leaves turned bro-n. This w very preliminary experiment, however, and cannot be considered at alconclusive.
UNIVERSITY OF FLORIDA 3 1262 09230 4103