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Insecticide Suggestions To Control Insect Pests Of Field Crops In 1980

Extension Bulletin 388- Revised 1980 AGRICULTURAL EXTENSION SERVICE UNIVERSITY OF MINNESOTA Suggestions To Control Insect Pests Of Field Crops In 1980

Legal Restrictions on Use of Pesticides In October 1977 certain provisions of the 1972 Federal Insecticide, Fungicide and Rodenticide Act became effective. In part, this, and the Minnesota Pesticide Act of 1976, require that those who use or supervise the use of certain pesticides with restricted uses must be certified. The labels ofthose pesticides with restricted uses will contain information regarding these restrictions. Be sure to read all labels thoroughly and use any pesticide for the crops and pests listed on the label only. The new law makes it illegal to use any pesticide in a way which is inconsistent with the label directions. Information about applicator certification may be obtained from your County Extension Director or the Minnesota Department of Agriculture. The U.S. Environmental Protection Agency (EPA) has listed the following as restricted-use : (Temik) Aluminum phosphide (Phostoxin) (Lannate, Nudrin) Azinphosmethyl (Guthion) Methyl bromide Calcium cyanide Methyl (Systox) (Phosdrin) Sodium cyanide Ethyl parathion Sulfotepp Tepp The following pesticides have been proposed for restricted use classification by EPA. After a period oftime for receiving comments EPA will issue a final order regarding the classification ofthese pesticides. Some ofthese products could have restricted use labeling during 1980.

Pesticide Restricted uses and formulations

aldicarb (Temik) agricultural uses of granules 10% and greater (other uses previously restricted) (Furadan) granules 2% and greater (except on pine and cottonwood plantation and nursery plantings) carbon disulfide grain fumigation, burrow treatments for woodchuck, ground squirrel, prairie dog, and rats chloropicrin formulations greater than 2%, all formulations for rodent control cyclohexamide (Actidione) formulations greater than 4%

The suggestions in this publication include only the use of insecticides for controlling insect pests of field crops. Other practices--such as crop rotation, time of planting, and appropriate selection of varieties--should also be considered.ln most situations, the use of insecticides is only part of a total effort to keep insect pests below the economic injury level. Where information is available, economic thresholds have been indicated in this publication. These are general guidelines that will vary, depending on stage of development of the crop, growing conditions, value of the crop, and other factors.

The information given in this publication is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Minnesota Agricultural Extension Service is implied.

Authors of this publication are J. A. Lofgren, professor and extension entomologist; D. M. Noetzel, assistant professor and extension entomologist; P. K. Harein, professor Agriculture. Roland H. Abraham, Director of Agricultural Extension Service, University and extension entomologist; and L. K. Cutkomp. professor, Entomology, Fisheries, and of Minnesota, St. Paul, Minnesota 55108. The University of Minnesota, including the Wildlife. Agricultural Extension Service, is committed to the policy that all persons shall have Issued in furtherance of cooperative extension work in agriculture and home eco~ access to its programs, facilities, and employment without regard to race, creed, color, nomics, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of sex, national origin, or handicap. 30'

2 Pesticide Restricted uses and formulations (DiSyston) granules 10% and greater; granules 2% and greater except seed beds and transplant beds; granules 5% and greater in combination with ethoprop 10% and greater (Bidrin) liquid formulations 8% and greater ethoprop (Mocap) granules and fertilizer formulations 3% and greater EPN formulations greater than 4%; granules 2% and greater (Nemacur) granules 10% and greater fensulfothion (Dasanit) granules and fertilizer combinations 2% and greater (Baytex) all formulations for aquatic, ornamentals, and bird control uses; all liquids 70% and greater fonofos (Dyfonate) granules 5% and greater (Monitor) liquids 40% and greater; dusts 2.5% and greater (Supracide) all formulations except on nursery stocks, safflower, and sunflower nicotine alkaloid formulations 14% and greater in greenhouses; all formulations on cranberries (Vydate) liquids 24% and greater (Thimet) granules 5% and greater temephos (Abate) aquatic uses; liquid formulations in orchards (Counter) granules 15% and greater zinc phosphide all dry formulations 60% and greater; all baits; all dry formulations 10% and greater for domestic uses

In addition, EPA has announced a final order classifying the following pesticides for restricted use. Restricted use labeling may show up on some of these products from now on, but registrants have a waiting period for getting restricted use labeling in place so many may not be labeled until spring 1980.

Pesticide Restricted uses and formulations carbofuran (Fu radan) all concentrates, suspensions, and wettable powders 40% and greater (4072) all concentrates, solutions, or emulsions 21% and greater clonitralid (Bayluscide) wettable powders 70% and greater; all molluscide uses (Delnav) concentrates, solutions, or emulsions 30% and greater; domestic uses of solutions 3% and greater disulfoton (DiSyston) concentrates 65% and greater; Emulsion Concentrates 21% and greater in combination with fensulfothion 43% and greater, E.C. 32% and greater in combination with 32% fensulfothion and greater; solutions 95% and greater for seed treatment; granules 10% and greater indoors (green houses) ethoprop (Mocap) Emulsion Concentrates 40% and greater fenamiphos (Nemacur) Emulsion Concentrates 35% and greater fensulfothion (Dasanit) Emulsion Concentrates and solutions 63% and greater; E.C. 43% and greater in combination with disulfoton 21% and greater; E. C. 32% and greater in combination with disulfoton 32% or greater fonofos (Dyfonate) Emulsion Concentrates 44% and greater (Azodrin) liquids 19% and greater

3 Pesticide Restricted uses and formulations phorate (Thimet) liquids 65% and greater; granules on rice phosacetin (Gophacide) 0.1% bait and greater (Dimecron) liquids 75% and greater; dusts 1.5% and greater

Others may be restricted during the year. In addition, the Minnesota Department of Agriculture has classified , some arsenicals, and some rodenticides as restricted. (Sevin), ULV , Methidathion (Supracide), Methyl parathion (Penncap M) and parathion are very toxic to bees. Crops in bloom should not be treated and applications should not be made near bee yards or when bees are present in the field to be treated. Some of the soil insecticides are toxic to fish. Use soil conservation practices to prevent soil erosion from treated fields. Avoid treating fields on steep slopes subject to erosion into surface waters. Aldicarb (Temik), demeton (Systox), disulfton (DiSyston), mevinphos (Phosdrin), methomyl, methyl parathion, parathion, phorate (Thimet), and phosphamidon (Dimecron) are highly toxic chemicals and should be used only by persons acquainted with the necessary precautions for their safe use. The granular formula­ tions are less hazardous to the operator than are the liquids. Avoid inhalation of dusts or vapors and contact with the skin. Follow directions on the labels for the use of protective clothing and other safety measures.

Limitations, remarks Crop Insect Insecticide Dosage (Days before harvest) Alfalfa Alfalfa weevil azinphosmethyl Y2-% lb. 21 days, one application per cutting (Guthion) carbofuran (Furadan) ~-Y2lb. 7 days~ lb., 14 days Y2 lb. methyl parathion ~lb. 15 days (lmidan) 1 lb. 7 days, one application per cutting plus Y21b.+ 7 days-available as a ready-to-use 1 lb. mixture malathion plus %lb.+ 7 days-available as a ready-to-use methoxychlor %lb. mixture methidathion (Supracide) Y2 lb. 10 days Cut first crop early to avoid most losses. Treat when over 30% of plant tips show feeding. Treat stubble if there are more than 8larvae per sq. ft. or when regrowth has 50% of the terminals with feeding or if larvae are delaying regrowth. Do not treat alfalfa in bloom. Aphids and diazinon Y2 lb. 7 days leafhoppers (Cygan, ~-Y2 lb. 10 days. One application per cutting. De-Fend, Rebelate, Dimex 267) malathion 1 lb. No time limitations parathion ~lb. 15days Control aphids when thick enough to cause wilting, usually during drought. Spotted alfalfa aphids may severely damage new seedings. Armyworm, carbaryl (Sevin) 1% lb. No time limitations, spray or bait cutworms malathion 1 lb. (or ULV) No time limitations trichlorfon (Dylox) 1 lb. spray or bait 7 days-spray methomyl (Lannate) ~-1 lb. 14 days-bait Treat when over 5 per sq. ft.

4 Limitations, remarks Crop Insect Insecticide Dosage (Days before harvest) Alfalfa Leafhoppers azinphosmethyl 1f4 to Y2 lb. 14 days carbaryl 1 lb. No time limitations diazinon 1/21b. 7 days methoxychlor 1 lb. 7 days malathion 1 lb. No time limitations methidathion Yz lb. 10 days (Supracide) phosmet 1 lb. 7 days. One application per cutting. Apply when regrowth after first cutting is 6 to 8 inches and leafhoppers are over 1 per net sweep. Treatment of third crop may be warranted in some cases. Combinations of methoxychlor with diazinon or malathion are also available. Grasshoppers azinphosmethyl Yz to% lb. 21 days carbaryl 1 to 1 Yz lb. No limitations carbofuran 2 to 4 oz. 7 days, one application per season. diazinon Yz lb. 7 days dimethoate 1f4 to Y2 lb. 10 days. One application per cutting. malathion 1Y2 lb. or Yz lb. 5 days, ULV technical as ULV No time limitations by air

Control when there are over 8 grasshoppers per sq. yd. in the field or treat margins after cutting at more than 20 per sq. yd. Spittlebug methoxychlor 1 lb. 7 days Apply on first crop when spittle masses average more than one per stem. Plant bugs malathion+ % lb.+ 7 days methoxychlor % lb. trichlorfon 1 lb. 7 days diazinon + Yz lb.+ 7 days methoxychlor 1 lb. Control seldom needed except on seed crop. Cut early to avoid injury. Alfalfa, clover Plant bugs (Thiodan) 1 lb. Do not harvest for forage or graze. (for seed only) 2 lb. Do not treat crop in bloom. Corn, Aphids malathion 1 lb. 5 days field methyl parathion 4 oz. 3 days } A . I I' . I parathion 4 oz. 12 days ena app 1cat1on on y phorate (Thimet) 1 lb. Granules applied in the whorl just before tasseliing. disulfoton (DiSyston) 1 lb. Granules 40 days disulfoton Yz lb. Spray 28 days. Chemical control of corn leaf aphids is seldom economically justified. If 10% of the plants have over 500 aphids per plant prior to tasselling during drought stress, treatment may pay. Armyworm carbaryl (Sevin) 111z to 2 lb. No time limitations malathion 1 to 1Yz lb. 5 days methomyl (Lannate) 1f4 to Yz lb. 3 days, forage toxaphene 2 lb. Do not feed stalks, leaves, or husks. No limitation for grain. trichlorfon 1 lb. No time limitations Treat when over 25% of the plants are infested with 2 or more larvae per plant. Higher rates for large worms.

5 Limitations, remarks Crop Insect Insecticide Dosage (Days before harvest) Corn, Corn rootworm carbofuran 1 lb. Planting time application of granules in 7- field larvae (Furadan) inch band over the row. Do not place in direct contact with the seed. Band of gran­ chI orpyrifos ules should be covered lightly. Some li­ (Lorsban) 1 lb. quid formulations are registered. If these are used with a starter fertilizer, be certain ethoprop (Mocap) 1 lb. they mix properly, are kept agitated, and fensu lfoth ion are placed in a split band away from the (Dasanit) 1 lb. seed.

fonofos (Dyfonate) 1 lb. Cultivation time applications of materials registered for such use may be made after phorate (Thimet) 1 lb. rootworm eggs hatch in June. Apply at base of stalks and cover with soil. This terbufos (Counter) 1 lb. method is not effective during dry condi­ tions and should be used as an emergen­ cy treatment only. Amaze (if registered) 1 lb. Rates given are for 40-inch row spacing. Rootworm control using chemicals may not be satisfactory in conditions of heavy infestation. In such situations, it is best to rotate to a crop other than corn. In some cases an insecticide may give inadequate control after successive years of use. This problem has been observed especially with such as carbofuran. To help prevent such failures rotate chemicals from year to year and avoid treating a field more than 2 consecutive years with the same compound.

Corn rootworm carbaryl 1 lb. No time limitations. Sevin-4 oil or dilute adults diazinon 1 lb. No time limitations malathion 1 lb. 5 days malathion ULV 4 to 8 oz. as 5 days technical by air phosmet Y4 to V2 lb. 14 days Treat when beetles are damaging silks enough to prevent proper pollination. This is usually 10 or more beetles per plant and before 50% of the silks emerge. Seed fields may need treatment more than production fields.

Corn Cutworms carbaryl 1 to 2 lb. Post emergence spray to cover approxi­ mately 12-inch band at base of plants in at spray or bait least 15 gal. total spray per acre. Limita­ tions same as for armyworm. Carbaryl trichlorfon (Dylox) 1 lb. bait is more effective than sprays for cut­ worms except under very dry conditions. These surface treatments are usually inef­ fective against subterranean species such as glassy cutworm. 1 to 1% lb. Broadcast by air or ground equipment. (Lorsban 4E) Apply when over 3% of the plants are cut. NOTE: chlorpyrifos (Lorsban 15G) is registered for cutworm control and may give control when applied at planting time as for rootworm control.

European corn carbaryl 1 Yz lb. Spray or granules, no time limitations. borer (First brood) carbofuran 1 lb. Granules. No more than 2 applications. diazinon 1 lb. Granules. No time limitations grain, 10 days forage.

6 Limitations, remarks Crop Insect Insecticide Dosage (Days before harvest) Corn European corn fonofos (Dyfonate) 1 lb. Granules. 30 days. borer (First brood) phorate 1 lb. As granules. 1 application. 30 days. toxaphene 2 lb. As granules. Use on corn for grain only. Treat when 50% of whorl leaves show shot-holing and the corn is at least 2ft., leaves extended. (35% irrigated, 25% seed fields). NOTE: Carbofuran (Furadan), fonofos (Dyfonate) or phorate (Thimet) should not be used in seed production fields to be detasseled by hand. Grasshoppers carbaryl 11/z lb. No time limitations. diazinon 1lz lb. No time limitations. malathion 1 lb. or 1lz lb. 5 days technical as ULV toxaphene 1 Y2 lb. For grain only, no time limitations. Treat field margins early when grasshoppers are small. Seed-corn , 1 oz. per bu. Seed treatment only. Will not control maggot, lindane heavy wireworm infestations. seed-corn beetle, wireworms Seed-corn fonofos (Dyfonate) 1 lb. Band in row at planting time as for maggots, beetles rootworm. Wireworm carbofuran 2 lb. In furrow at planting time (Furadan) ethoprop (Mocap) 1 lb. As for rootworm. ph orate 1 lb. As for rootworm. terbufos (Counter) 1 lb. As for rootworm or in furrow. diazinon 4 lb.} Broadcast, disc in before planting. fonofos (Dyfonate) 41b. Small grains Aphids malathion 1 lb. methyl parathion 4 oz. No limitations. methyl parathion 6 to 8 oz. 15 days (Penncap M) parathion 4 oz. 15 days dimethoate Y4 to % lb. Wheat only. 60 days. disulfoton Y4 to % lb. 30 days. For wheat only. Do not graze. Treatment most economical before heading with over 100 aphids per ft. of row (50 greenbugs).

Armyworm, malathion 11/z lb. 7 days cutworms trichlorfon (Dylox) 21 days, maximum of 3 applications. toxaphene 2 lb. Use for grain only. Treat when number of worms exceeds 5 per sq. ft. Grasshoppers (Orthene) 1/s lb. Wheat only. dimethoate (Cygon) Y4-11z lb. Wheat only. 10 days. malathion 1 lb. or 1lz lb. 7 days as technical by air methyl parathion 1lz lb. 15 days (Penncap M) toxaphene 11/z lb. Use for grain only. Treat when over 8 per sq. yd. in field or over 20 in margins. Wireworms heptachlor or 1 oz. per bu. Seed treatment only. lindane

7 Limitations, remarks Crop Insect Insecticide Dosage (Days before harvest) Barley Thrips parathion or methyl 6 oz. 15 days. Apply just at heading when there parathion by air are 4 or more adult thrips per plant. Flax Cutworms, crickets trichlorfon 1 lb. 21 days. Soybeans Bean leaf beetle, carbaryl (Sevin, 1 lb. No limitations. flea beetles, Sevimol) blister beetles Treat when defoliation exceeds 25% during pod fill or seedling stage or when pod feeding is extensive. Cutworms, carbaryl 1% lb. No limitations. Armyworms toxaphene 1 Y2 lb. 21 days. Do not feed treated plants.

Grasshoppers acephate ~to Y2 lb. 14 days. Do not feed forage. carbaryl 1% lb. No limitations. dimethoate ~ to Y2 lb. 7 days malathion % lb. technical 7 days as ULV by air toxaphene 1% lb. 21 days. Do not feed treated plants. Green cloverworm azinphosmethyl 6 to 8 oz. 45 days. Bacillus thuringienis (Dipel, Thuricide) As labeled. carbaryl 1 lb. No limitations. dimethoate ~ to % lb. 7 days malathion 1 lb. 7 days Treat when defoliation exceeds 25% or when worms number more than 15 per foot of row during pod fill. Leafhoppers malathion 1 lb. 7 days Sugarbeets Webworm carbaryl (Sevin) 1% lb. 14 days, tops. endosulfan (Thiodan) 1 lb. Do not feed tops. parathion 4 to 8 oz. 15 days trichlorfon (Dylox) 1 lb. 14 days Treat when worms exceed 5 per sq. ft. Cutworms carbaryl 2 lb. spray 14 days, tops. Bait formulation preferred. 1 to 2 lb. bait chlorpyrifos 1 lb. Row treatment at planting time. (Lorsban) trichlorfon 1 lb. 14 days Root maggots aldicarb (Temik) 1% lb. Row treatment at seeding time. Place carbofuran 2 lb. granules above seed in 5 to 7 inch band or chlorpyrifos 1 lb. as furrow treatment above seed. Some (Lorsban) products may also be sidedressed at time diazinon 1 to 2 lb. of fly emergence. Check labels. fonofos (Dyfonate) 1 to 1% lb. terbufos( Counter) 1 to 2 lb.

Wireworms lindane 1 oz. per bu. Seed treatment only. diazinon 2 to 4 lb. Broadcast incorporated. fonofos 41b. Soil treatment pre-plant. Sorghum Green bugs ethyl parathion %lb. 12 days, aerial application. Methyl para­ thion may cause plant injury. dimethoate ~to% lb. 28 days disulfoton %to 1 lb. 7 days (grain). May be as granules at planting. malathion 1 lb. 7 days MetaSystox R ~to% lb. 21 days. ph orate %to 1 lb. 28 days

8 Limitations, remarks Crop Insect Insecticide Dosage (Days before harvest) Sorghum Wireworms heptachlor or Y2 to 1 oz. per Seed treatment lindane bu. Sunflower Sunflower moth endosulfan 1 lb. Not more than 3 applications. Do not feed larvae (Thiodan) treated plants. No limitations on use of seeds. Highly toxic to bees. methidathion %lb. 2 or 3 treatments at least 50 days before (Supracide) harvest. methyl parathion 1 lb. No more than 3 applications. 5 day inter­ vals 30 days before harvest. Highly toxic to bees. One larva per head in every plant in the field will cause approximately 151b. per acre yield reduction.

Grasshoppers, toxaphene 1% t-o 2 lb. No more than 2 applications. Do not graze sunflower beetles, or feed plant parts. No time limitations for thistle caterpillars seed. Higher rates for grasshoppers. Plants can be defoliated at least 25%with no yield reduction. Stem weevil methidathion % lb. 50 days before harvest. (Supracide) 2 adults/plant at 10 to 20 leaf stage Cutworms Toxaphene 1% to 2 lb. Use higher rates. Not more than 2 applica- tions. Do not graze or feed plant parts. Lorsban 1 Y2 lb. For seed production fields only. Treat when plant population is 75% of that recommended for area. Seed fields can tolerate little stand reduction. Seed weevil Supracide Y2 lb. 50 days before harvest. Treat before onset 20 adult weevil/plant. of bloom. Avoid interfering with pollina­ tor activity. Wild rice Wild rice worm malathion 1 lb. 21 days before harvest. (in paddies) One larva per head =11% damaged kernels per head. Bluegrass Plant bugs diazinon % lb. No time limitations (for seed) (Capsus) malathion % lb. No time limitations Treat as heads emerge when Capsus bugs are detected or at first sign of silver top. Bluegrass, Meadow plant bug malathion % lb. No time limitations Timothy Treat at early heading stage when there is an average of two bugs per net sweep. (for seed) Armyworm carbaryl 1% lb. No time limitations malathion 1 lb. No time limitations Treat when there are 5 worms per sq. ft. Corn, sweet (for processing) NOTE: See precaution on bees, p. 4. Aphids diazinon % lb. no time limitations malathion 1 lb. 5 days parathion Y2 lb. 12 days Armyworm carbaryl 1% to 2 lb. no time limitations malathion 1 lb. 5 days methomyl Y4 to Y2 lb. No time limitations (3 days, forage) Cutworms carbaryl 2 lb. bait or spray No time limitations diazinon 4 lb. Broadcast incorporated, soil treatment, preplant trichlorfon 1 lb. No time limitations

9 Limitations, remarks Crop Insect Insecticide Dosage (Days before harvest) Corn, sweet (for processing) NOTE: See precaution onbees, p. 4. Corn earworm carbaryl 1% to 2 lb. no time limitations diazinon 1% lb. no time limitations methomyl Y-1 to Y2 lb. no time limitations (3 days, forage) methyl parathion Y2 lb. 3 days, (12 days forage) (Penncap M) European corn Bacillus thuringiensis (as labeled) no time limitations borer carbaryl 1 to 2 lb. no time limitations diazinon 1 to 2 lb. no time limitations methomyl %lb. (3 days forage) methyl parathion %lb. 3 days (12 days forage) (Penncap M) Corn rootworm fonofos ethoprop see field corn ph orate terbufos Seed corn maggot diazinon 1 oz./bu. seed treatment Peas (for processing and dry field peas) Aphids diazinon % lb. no time limitations (4 days hay or forage) dimethoate 1/s to Y-1 lb. (4 days hay or forage) (do not feed vines) mevinphos 1/s to Y-1 lb. 1 day 1 to 2 lb. 4 days (Dibrom) oxydemeton methyl % lb. 21 days (MetaSystox-R) parathion Y-1 to % lb. 10 days (15 days forage) Loopers, carbaryl %lb. no time limitations armyworms parathion Yzlb. 10 days ( 15 days forage) methomyl %to 1 lb. 1 day (5 days for feeding to livestock) Seed corn maggot diazinon 1 oz./bu. Seed treatment Dry Beans Aphids diazinon %lb. 7 days (4 days hay, 1 day forage) dimethoate %lb. no time limitations; do not feed endosulfan %lb. 3 days; no more than 3 applications Bean Leaf Beetle, carbaryl 1 lb. no time limitations Green Cloverworm Leaf hoppers carbaryl 1 lb. no time limitations diazinon %lb. 7 days dimethoate Y-1 lb. do not feed treated vines endosulfan %lb. 3 days; no more than 3 applications malathion 1 lb. 1 day methoxychlor 1 lb. 1 day oxydemeton methyl %lb. 21 days Spider mites (Kelthane) %lb. 7 days %lb. 2 days; do not feed foliage oxydemeton methyl %lb. 21 days Seed corn maggot diazinon} lindane 1 oz. per bu. as seed treatment Wireworms, diazinon 3% lb. broadcast incorporated soil white grubs treatment before planting

10 Stored Grain Insects

Grain in Minnesota is relatively safe from infestation by stored grain insects before harvest. The only exception may be where grain is cut and swathed adjacent to storage bins being treated with an insecticide or fumigated in preparation for the new crop. Stored-grain insects will migrate from treated bins, at least temporarily. Accumulations of post-harvest grain or grain products is a primary target for insect infestations especially if it is stored with or adjacent to last year's crop. Overfilling the bin to peak will not allow adequate inspection or treatment. Inspect grain at 7-day intervals, during the summer and autumn months, to determine if treatment is needed. Check for insects by taking the grain temperature and by looking for the insects, insect webbing, and insect damaged grain. To take the grain temperature, fasten a thermometer to a stick and sink it into the grain 2 feet below the surface or determine the grain temperature by placing a thermometer in the exhaust air from the aeration system. If insects are active, the temperature will be above 65°F, and may range as high as 100°F. To inspect for insects, insert a grain probe in the center of the bin 2 feet below the grain surface. Sift the grain samples through a 10 to 12 mesh-to-the-inch screen to separate out insects.

Prevention Spraying Facilities: Thoroughly clean combines, trucks, wagon beds, elevators, and bins. Spray the surfaces of the equipment that will be in contact with the grain with one of the following insecticides 2 to 6 weeks before harvest: Pesticide Amount of pesticide formulation formulation per 2 gallons of water methoxychlor 50% W.P ...... 12 oz. or methoxychlor 25% E.C...... 1 qt. or 6% E.C. combined ...... 1% pts. with piperonyl butoxide 60% or malathion- premium grade ...... % pt. oz. =ounce W.P. = wettable powder qt. = quart E.C. = emulsifiable concentrate pt. =pint Spray to the point of run-off using 1 gallon of total formulation (one of the insecticides listed above) per 500 sq. ft. of surface. Also spray, if possible, the outside walls ofthe bins to a height of6feet and the ground to a distance of 6 feet out from the foundation of each bin. If it is not possible to remove the old grain, then it should be checked carefully for stored-grain insects and, if needed, treated with recommended residual insecticides or fumigants before adding new grain. Grain stored below 50° F is relatively safe from significant damage by stored-grain insects.

Grain Protectants: Insect infestations are prevented or reduced by treating small grains and shelled corn as it is moved into storage. Treatment may be delayed until spring if air temperatures moved through the grain at initial storage time will cool the grain down to 50°F in a few days. malathion 1 pt. premium-grade E.C. per 2 to 5 gal. water per 1,000 bu. malathion 1% premium-grade wheat flour dust, 60 lb. per 1,000 bu. synergized pyrethrins 1 qt. of pyrethrins 6% combined with piperonyl butoxide 60% E.C. in 3 to 5 gal. of water per 1,000 bu. Spray onto the grain stream as it goes into storage.

Bacillus 0.1 lb. Dipel W.P./gal. water and mix with top 4 inches of grain at the rate of thuringiensis 0.6 pt./bu. grain or soybeans. Dipel is also available in a dust formulation. Surface Grain Treatments: Chemical - malathion %to 1 pint premium-grade E. C. in 2 gal. water per 1,000 sq. ft. of grain surface area. malathion 1% premium-grade wheat flour dust, 30 lb. per 1,000 sq. ft. synergized pyrethrins 8 oz. of pyrethrins 6% combined with piperonyl butoxide 60% E. C. in 1 to 2 gal. of water per 1,000 sq. ft. of grain surface.

11 Biological - Bacillus thuringiensis 1 lb. of Dipel W.P. in 10 gal. water per 500 sq. ft. of grain (Dipel@) surface and mix into top 4 inches of surface grain. May also be applied as a dust and on stored soybeans. Will control Indian meal moth and almond moth larvae only.

Apply surface grain protectants (1) immediately after the grain is loaded into storage and leveled off or (2) mix it into the last 4 inches of surface grain being augered into the bin. The Indian-meal moth is generally found in the top 6 to 12 inches of stored shelled corn. At the same time there is evidence from some areas that this moth is developing resistance to malathion. If malathion is ineffective, apply synergized pyrethrins, fumigants, or Bacillus thuringiensis. A preventative treatment for moths is to suspend 1 (Vapona) "Farm Strip" per 1,000 cubic ft. of space over the binned grain before moths begin to emerge in early spring. This treatment is usually effective for 4 months. Replace strips when effectiveness diminishes. Control

Fumigation: Fumigants 1 are applied to binned grain to stop established insect infestations. Best fumigation results are obtainable using the following guidelines: 1. Level the grain. Remove or breakup any crust on the grain surface. 2. Seal all cracks making the bin as air-tight as possible. 3. Fumigate on a still day preferably when the grain temperature is above 60°F. Wind causes rapid leakage ofthe gas and insect kill may be poor. 4. Methods of applying fumigants vary with the type of fumigant, commodity, and storage facility. Most farm storages use the gravity penetration method. Apply the correct amount of liquid fumigant evenly over the surface of the grain. Cover the grain with a tarpaulin if the bin is not full. 5. The operator should stay out of the bin if applying liquid grain fumigants. Phosphine formulations allow 1-2 hours before phosphine is generated. 6. Do not breathe vapor or fumes. Use a recommended gas mask with canister, and always work in pairs. 7. Keep the bin closed for at least 72 hours. Do not enter the bin during or after fumigation until the fumigant has been allowed to dissipate. 8. When under fumigation, the storage bins should be locked and identified with "DANGER-KEEP OUT" signs to prevent entry and avoid accidents. 9. It often is safer, less expensive, and more effective to have your stored grain fumigated by a licensed and certified professional fumigator than to do it yourself. This applies especially to single upright bins containing more than 5,000 bushels. Flat storage structures present additional problems because of the relatively large grain surface area where insects congregate and fumigants quickly dissipate to ineffective concentrations. Some of the recommended fumigant dosages are tabulated below: Dosage (gal. per 1,000 bu.) Small grain Shelled corn Wooden Metal Wooden Metal Fumigant bins bins bins bins -carbon disulfide, 80-20 ...... 4 2 6 3 Carbon tetrachloride-ethylene dibromide, 95-5 ...... 4 2 8 4 Carbon tetrachloride-ethylene dichloride, 3-1 ...... 6 3 8 4 Carbon tetrachloride-ethylene dichloride- ethylene dibromide, 60-35-5 ...... 4 2 8 4

1 Fumigants, being highly toxic, are being restricted and require the certification of applicators. Use other liquid fumigant formulations as labeled. Aluminum phosphide Tablets may be added to the grain as it is being binned or they can be probed into the grain surface after the bin is filled-the suggested dosage is 180 tablets/1 ,000 bu. Type of storage Grain temperature Dosage (per 1,000 bu.) Tablets Pellets Concrete or steel 54-59°F. 150 500 elevator tanks 60-68°F. 90 300 over 68°F. 60 200

Read and follow all precautions listed on the labels for each different fumigant. Repeat fumigants may be necessary. Information about other fumigants is available from the Department of Entomology, Fisheries, and Wildlife, University of Minnesota.