Flint, W.P.

Mohr, Carl Otto

English

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b RAR.YOF THEUNIVERSITYOF ILLINOISG30.714Gbho.354-3G3Cop.2*JWRICUITUREThe person charging this material is responsible forits return to the library from which it was withdrawnon or before the Latest Date stamped below.Theft, mutilation, and underlining of books are reasons for discipli-nary action and may result in dismissal from the UniversityTo renew call Telephone Center, 333-8400UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGNAPR 2 8 2(LI61 O-I096New Protection AgainstStored-Grain InsectsBy W. P, FLINT ANDC. O. MOHRBulletin 359University of IllinoisAgricultural Experiment StationFormula for Making Oil Emulsion to Protect StoredCorn From Insect InjuryA stock emulsion of boiled lubricating oil (homemadedormant oil emulsion) that has proved successful in pro-tecting stored corn against insect damage and does not in-jure germination, is made by the following formula :Light-grade lubricating oil 1 gallonWater 1 quartPotassium oleate 1 to 2 pounds,depending on the hardness of the water; very hardwater requires the larger amount.The light-grade lubricating oil required in the aboveformula will give the best results if it meets the followingspecifications: (1) specific gravity at 20 C., .87 to .93; (2)volatility at 110 C. for 4 hours not above 10 percent;(3) viscosity at 100 F., 90 to 150 seconds, Saybolt test.To make the stock emulsion, boil the water, oleate, andoil together for 5 minutes, taking care not to burn the mix-ture; then pump it thru a spray pump at 150 to 250 poundspressure or use an electric mixer.The commercial oils mentioned in these investigationscan be purchased thru dealers in insecticides. There aremany commercial oils other than those used that mayafford equally good protection against insect injury tostored grains, but obviously it was impracticable to at-tempt to include all in these tests.For directions for applying the emulsion to earcorn, see back cover pageUrbana, Illinois November, 1930Publications in the Bulletin series report the results of investigationsmade or sponsored by the Experiment Station.New Protection Against Stored-Grain InsectsBy W. P. FLINT, Chief Entomologist, Illinois Natural HistorySurvey, and C. O. MOHR, Assistant EntomologistO heavy and sure is attack by grain moths and beetles that corncannot be stored without protection for more than one season'without its being severely injured. Even with present methodsof caring for grain, the measurable loss runs constantly above themillion-dollar mark in many states and into several millions in each ofthe Southern states. A greater, unmeasurable loss is due to the earlysale of grain forced by present short-time controls, for one may nothold grain more than a season except by constant vigilance, frequentfumigation, and some loss in spite of great care.Seed corn kept in storage in the usual ways is always subject toinjury by certain of the grain-infesting moths and oftentimes byweevils and beetles. As a result of five years' experimental work ithas been found that some of the oil emulsions developed for the con-trol of orchard insects will protect seed corn from stored-grain insects.This method may also be applied for the protection of corn stored forfeed. Protection is sure, safe, and enduring, as shown by the way inwhich the treated corn has been protected against injury when sub-jected to severe exposure to insect pests and the successful germinationof the corn thereafter.This publication is a statement of the results obtained in tests withcorn. A later publication will give the result of applying oil emulsionsto other grains. The information will be made available as soon asa series of experiments now under way is completed.Insects causing damage to stored grain are mainly larvae of mothsor adults and larvae of beetles. Among the most destructive are therice weevil and Angoumois grain moth. The adults of these two insectsfly freely and the larvae develop inside the seed, destroying it com-pletely. The Cadelle, the granary weevil, the confused flour beetle,tin- Mediterranean flour moth, and the saw-toothed grain beetle fre-quently cause severe damage to stored seed and feed corn.Drawbacks to Protective Methods Now in UseAt the present time a number of methods are employed to pre-vent damage to stored seed and feed corn. One of the most effective377378 BULLETIN No. 359 [November,is that of thoroly cleaning out all storage rooms, bins, or buildings be-fore the grain is stored and placing only clean corn in storage.The method generally employed where infestations have becomeestablished is fumigation by hydrocyanic acid gas, carbon bisulfid,ethylene oxid, or other chemicals. Fumigations are effective if thebuilding is made properly gas-tight, the right dosage of the chemicalsis used, and exposure is maintained for a sufficiently long period atthe proper temperature and humidity. Fumigation is always ratherexpensive and has the disadvantage of not giving protection fromreinfestation;that is, a room used for the storage of seed corn maybe fumigated and all corn-infesting insects killed, but by the next dayor week other insects may be reintroduced into the room, making itnecessary to fumigate again within a short time.Treatment with heat protects stored corn when proper equipmentand conditions can be provided. If seed corn is to be so treated, caremust be taken that the temperature does not rise above 135 F. orfall below 120 F. ; that the temperature is maintained for approxi-mately six hours; and that the corn does not contain less than 12percent or over 20 percent moisture.Thus present methods of preventing insect damage to seed andfeed corn have not been entirely satisfactory. An attempt was there-fore made to find a method for protecting seed corn, and possiblystored feed corn, that would be less expensive than other methods,would give protection over a longer period, and would require theminimum amount of skill and equipment for applying.New Methods Given Severe TestThe conditions under which the tests herein described were madewere as severe as possible.Ears of corn were treated by being dipped in certain oil emulsions.In one test the ears were dusted with calcium fluosilicate dust. Five toten ears were treated with each material. These ears were then placedon flat screen-bottomed trays that allowed insects to have access to thecorn from all sides. These trays were kept in rooms where hundredsof thousands of Angoumois grain moths were being reared in con-nection with work on one of the egg parasites, the Angoumois grainmoth being used to supply the eggs for rearing this parasite which islater liberated in the field where it attacks the eggs of a number ofother insects. Not only was the Angoumois grain moth present inthese rooms in excessively large numbers, but moderate numbers of1930} PROTECTION AGAINST STORED-GRAIN INSECTS 379FIG. 1. EXPOSED SIDE BY SIDE FOR FIVE MONTHS IN MOTH ROOMThe ear on the left was dipped into a commercial dormant spray oil(Dendrol) diluted in the proportion of 1 part of oil to 10 parts of water. Thisoil gave excellent protection but injured the subsequent germination of the corn.Note holes in ear at right, which was not treated.380 BULLETIN No. 359 [November,^VOLCK I- 10CHECKFIG. 2. TREATED AND UNTREATED EARS KEPT IN MOTH ROOM FOR Six MONTHSThe ear at the top was treated with commercial summer spray oil (Volck)diluted 1 part of oil to 10 parts of water. The lower ear was treated with acommercial summer spray oil (L-43) diluted 1 to 8. The ear in the centerwas left untreated. Both these oils gave excellent protection and permittednormal germination.the Indian meal moth were also present, and considerable numbers,at times rather large numbers, of the granary weevil, the rice weevil,the confused flour beetle and the saw-toothed grain beetle. The roomswere kept at a temperature of 75 to 85 F. and a humidity of ap-proximately 40 to 50 percent.The corn was allowed to remain in the trays for a number ofmonths. In no test was the period less than five months. After thisperiod, the ears were shelled and grains of corn from the ears of eachtreatment were mixed together to make a composite sample, and onethousand to five thousand kernels from each treatment were care-fully examined for infestation by insects.1930] PROTECTION AGAINST STORED-GRAIN INSECTS 381Untreated ears were always handled in the same way as the treatedears and were examined and counts made in the same manner. Atvarious times during the course of the treatment and at the conclusionof each test, a number of grains were removed from the treated anduntreated ears and were tested for germination, these tests being car-ried on by the Department of Agronomy.Three Oils Prove WorthThe first series of tests reported herein were made during 1928-29.They were based on results of tests made in earlier years, and areTABLE 1. RESULTS OF FIRST SERIES OF TESTS IN TREATING SEED CORN ON THEEAR WITH OILS, DUST, AND ACID: OCTOBER, 1928-FEBRUARY, 1929Treatment382 BULLETIN No. 359 [November,INFESTED UNINFESTEDCRESYLIC1-2OCRESYLIC1-10FIG. 3. EFFECT OF CRESYLIC ACID IN Two DILUTIONSThe stronger sohition (1 to 10) gave the better protection but injuredgermination.here recorded as showing some decidedly useful trends. The follow-ing materials were used:Homemade boiled lubricating oil emulsion (with potassium oleate, see in-side of front cover page)Three commercial oilsCresylic acid (1 part to 10 parts of light, refined mineral oil)Calcium fluosilicate dustThe liquid preparations were applied by dipping the ears slowlyenough to permit thoro penetration; the dust was applied by rollingand working it into the ears. The protection afforded by these treat-ments is shown in Table 1 ; the germinating powers of the treated seedare shown in Table 2.Seed treated with the homemade boiled lubricating oil emulsionin the l-to-10 dilution (1 part of emulsion to 10 of water) and thattreated with two of the commercial oils (Volck and L-200) showedgood germination and was well protected. These materials weretherefore retained for a second set of tests. Cresylic acid injured the1930] PROTECTION AGAINST STORED-GRAIN INSECTS 383CHECKUNINFESTEDVERDOL1-10FIG. 4. SOME TYPES OF COMMERCIAL OIL EMULSION Do NOTGIVE SUFFICIENT PROTECTIONAfter six months' exposure in the moth room about 45 percent of thetreated kernels were infested. All but 2 of the 200 untreated kernels were in-fested.seeds, but gave such excellent protection that weaker solutions of itwere tried in the second series in the hope that it might give satisfac-tory protection and cause less injury to the germinating powers ofthe corn. Calcium fluosilicate dust, commercial oil formula L-263, andthe l-to-20 dilution of the homemade boiled lubricating oil emulsionfailed to prove at all promising and were eliminated from the tests.In the second series of tests (Tables 3 and 4) the homemade boiledlubricating oil was tried in a l-to-15 dilution as well as in the l-to-10dilution. In addition to Volck and commercial oil formula L-200, twoother commercial oils (L-43 and Verdol) were tried.Of the materials used in this second series, the homemade boiledlubricating oil emulsion in the l-to-10 dilution, commercial oil formulaL-43, and Volck protected over 95 percent of the corn treated withthem and gave satisfactory germination. The untreated corn was com-pletely riddled by moth infestation. Cresylic acid and two of the com-mercial oils (Verdol and L-200) proved unsatisfactory.384 BULLETIN No. 359 [November,TABLE 3. RESULTS OF SECOND SERIES OF TESTS IN TREATING SEED CORN ON THEEAR WITH OILS AND ACIDS: 1929(Period of exposure to insects 7 months)Treatment1930] PROTECTION AGAINST STORED-GRAIN INSECTS 385TABLE 5. RESULTS OF THIRD SERIES OF TESTS IN TREATING SEED CORN ON THEEAR WITH OILS AND POTASSIUM OLEATE: 1930(Period of exposure to insects, 5 months)Treatment386 BULLETIN No. 359 [November,FIG. 5. EFFECT OF DIFFERENT DILUTIONS OF HOMEMADE OIL EMULSIONSThe l-to-10 dilution of boiled homemade lubricating oil emulsion made withpotassium oleate gave good protection and did not injure germination. Thel-to-15 dilution was too weak to protect against infestation.Each of these substances protected 80 percent or more of the corn,while pests riddled 100 percent of the untreated corn, and each per-mitted a germination of over 90 percent. Two, the homemade emul-sion in the l-to-10 dilution and L-43 in the l-to-10 dilution, permitteda germination of 95 percent of the kernels, equalling that of the un-treated corn.Preliminary Tests of Feeding ValueIn preliminary tests conducted by the Animal Husbandry De-partment of the Illinois Station, the feeding of treated corn to some1930} PROTECTION AGAINST STORED-GRAIN INSECTS 387FIG. 6. ALMOST COMPLETE PROTECTION WAS AFFORDED BY CERTAINTYPES OF COMMERCIAL OIL EMULSIONSAfter six months' exposure in the moth room only 6 of this compositesample of 200 grains treated with Volck were found infested. Of the 200-kernel sample of the grains treated with L-43, only 4 were found infested.farm animals (in this case corn treated with Dendrol) produced no in-jurious effects on the animals, and the corn was just as palatable asuntreated corn.Three different oil emulsions were also tested by being fed to rats.Five times the amount of emulsion that an animal would obtain fromtreated ear corn was mixed with the ration. Some injurious effects re-sulted in these tests. In the case of tests with highly refined oils,only a slight effect on the rats was noted.It seems improbable that treated corn would cause any injury tohorses, cattle, hogs, or chickens, but further tests are necessary.388 BULLETIN No. 359SummarySome of the common oil emulsions and miscible oils now generallyused for spraying fruit trees will protect ear corn dipped in these mix-tures from attack by many of the insects that injure stored grain.Seed corn treated with commercial emulsions made from highlyrefined oils was effectively protected from insect injury and the germi-nation of the corn was not affected.Boiled homemade lubricating oil emulsion was very effective inprotecting ear corn against damage by insects. When potassium oleatewas used in such emulsion, germination was not injured.Some of the commercial miscible oil orchard sprays gave verygood protection but injured germination.Preliminary feeding tests would seem to indicate that treatedcorn can be fed to horses, cattle, hogs, and chickens without harmfuleffect.Treating Ear Corn to PreventInsect DamageTo treat small amounts of ear corn, mix the re-quired amount of oil emulsion in water at the rateof 1 gallon of emulsion to 10 gallons of water. Ap-proximately 1 quart of this diluted oil emulsion willtreat a bushel of corn.A tub or convenient small tank can be used. Placethe corn to be treated in slatted crates or ordinarybushel baskets. Dip corn and container in the liquid ;remove immediately and place on a drain board whichwill permit the excess liquid to run back into thedipping tank. Slatted crates are better containersfor this purpose than bushel baskets as the crates aremore open and will permit a quicker dipping anddraining.After being dipped, the corn should be thorolydried and then stored without any more handlingthan is absolutely necessary. It apparently is thethin film of oil which surrounds each kernel that pro-tects the corn from insect injury, and if the corn ishandled, this film is broken and the corn renderedliable to injury.For directions fof making the oil emulsionsee inside of front cover page.

New protection against stored-grain insects

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