Recommendation for Control of Stored Grain Insects

Published: September 1, 2011

BEFORE HARVEST

SANITATION. Thoroughly clean all grain residues from bins. Remove all residues from areas around the bins and any nearby feed bunks or feed storage areas. Remove all grain residues from combines, trucks, and augers. These residues will be the main sources of insect infestations for farm stored grain. This is a very important part of a good grain management program and can prevent many stored grain insect problems.

RESIDUAL SURFACE SPRAYS TO EMPTY BIN. After all debris and grain residues have been removed, a residual insecticide should be sprayed to the entire inside of the bin. This insecticide should also be applied around the exterior and to all areas where residues were removed. Spray all surfaces until wet; usually one gallon will cover 1,000 square feet. Use a course spray at a pressure of at least 30 psi. Insecticides are most effective if temperatures are 60F or higher. The labeled effective compounds are:

1. Beta-Cyfluthrin (Tempo SC Ultra - 0.27 to 0.54 fl oz per 1 gallon of Water) for application to empty bin surfaces only, not to grain.
2. Chlorpyrifos-methyl and deltamethrin (Storcide II – 1.8 fl oz per 1 gallon of water) Warning-This insecticide should only be applied from outside the bin using automated spray equipment. Do not enter the bin until all sprays have dried.
3. Malathion (Malathion 5E - several products by various formulators, check specific application rates.) The efficacy of this product is questionable although labeled. Some stored grain insect populations, such as Indian meal moth, have developed resistance to this insecticide. Note: Malathion 5 E not labeled for rice.

AT HARVEST GRAIN PROTECTANTS

PROTECTANTS FOR APPLICATION TO GRAIN. If grain is to be held in storage into the summer months of the year following harvest or longer, then a grain protectant applied at harvest is recommended. Formulated sprays, drips or dusts are typically applied to moving grain stream as it goes into storage vessel.

1. Chlorpyrifos-methyl + deltamethrin (Storcide II) – dilute labeled rate of Storcide II in 5 gallons of water and apply formulated spray into grain stream. Five gallons of formulated spray applied to 1,000 bushel of grain. Storcide II rates per 1,000 bushel of grain crop are as follows: Barley 9.9 fl oz per 1,000 bushels; Oats 6.6 fl oz per 1,000 bushels; Rice 9.3 fl oz per 1,000 bushels Sorghum 11.6 fl oz per 1,000 bushels Wheat 12.4 fl oz per 1,000 bushel
2. Pirimiphos-methyl (Actellic 5E – 9.2 to 12.3 fl oz per 5 gallons of water per 30 tons of grain (approximately 1071 bu.). Note: labeled for corn and sorghum only.)
3. Malathion (Malathion 6% Dust – 10 lbs/1,000 bushels of grain.) Insecticide dust best applied through dust applicator into grain stream. Labeled for barley, corn, oats, rye, and wheat. Malathion not labeled for use on rice.

SURFACE TREATMENTS OR TOPDRESSING AFTER BIN FILL IS COMPLETE. Fill bins only to height of side walls and level grain prior to applying surface or top-dress insecticide treatments.

1. Bacillus thuringiensis (Biobit HP and Dipel DF – 1 lb/ 10-20 gal/1,000 square feet). Most often used for Indian meal moth larval control. See label for specific instructions and target pests.
2. Diatomaceous earth (Insecto at 4 lbs/1,000 square feet and Protect-It at 40 lbs/1,000 square feet if grain not previously treated with this protectant). See label for specific instructions and target pests.
3. Pirimiphos-methyl (Actellic 5E – 3.0 fl oz per 2 gallons of water per 1,000 square feet of grain surface. Note: Labeled for corn and sorghum only.)

GRAIN FUMIGANTS. Recommend use of commercial pest control specialist when using grain fumigants for stored grain insect control.

1. Aluminum Phosphide (phosphine gas - restricted use) (Phostoxin, Fumitoxin, Phoskill, Phosteck, Phosfume Weevil-cide – see specific labels for rates of pellet or tablet use).

MONITORING FOR INSECT PESTS IN STORED GRAIN Bins should be monitored every one to two weeks when grain mass temperature is above 60F and every two to four weeks when grain temperature is below 60F. Monitoring is best achieved using plastic tube traps which are inserted into the grain mass for a certain period of time and then retrieved (see trap label for specific instructions). This type of trap will attract insects and help determine the kind and number of insects present in the grain mass. Be sure to cool grain mass in fall to 60F or less to prevent insect activity. In the spring the grain mass should be warmed to average outside temperatures to prevent condensation and subsequent moisture damage to grain in contact with bin walls.