ISSUE 16 August 18, 2005
MANAGEMENT OF STORED GRAIN INSECT PESTS
Grain insect pests can cause economic damage to stored grains by reducing weight, nutritional value, and germination. Infestations also cause contamination, odor, mold and heat problems that reduce the quality of the grain and may make it unfit for processing into food for humans or animals. Producers may receive a reduced price for contaminated grain or it may be completely rejected by commercial grain buyers.
Preventative Measures before Binning Grain: Newly harvested grain may become infested with grain insects by contacting previously infested grain in combines, truck beds, wagons, augers, bucket lifts, grain dumps, and other grain-handling equipments, or old grain already in the bin. Insects can also crawl or fly into grains bins from old contaminated grains/debris. Use the following guidelines about two-three weeks before grain is placed in the bins to prevent severe insect infestations.
Preventative Measures during Binning: If grain is to be stored for one year or more, it is a good idea to apply a grain protectant. Grain protectants are insecticides registered for application to whole grain to protect against insect infestation while the grain is in storage. Grain protectants kill insects as they crawl about or feed on treated grain and/or grain fragments. These formulations are generally applied to grain as it is being augured, loaded, or turned into storage facilities.
Registered grain protectants in North Dakota include: corn/sorghum - acetellic 5E; wheat, barley, oats, sorghum, corn - diacon II, malathion, reldan (product is being phased outs, not for corn), storicide, and storicide II. Grain drying in bins during high temperatures will reduce the residue of insecticide due to rapid volatilization. Residue is also reduced when applied to grain with higher moisture. Always read and follow label directions when applying any insecticide.
Preventative Measures after Binning: A surface treatment can be applied to "top dress" or "cap off" the grain already in storage. This protects the grain mass from surface feeding insects, such as the Indian meal moth. It is recommended to remove any crusting or webbing first and then to rake insecticide into top few inches of grains to increase the efficiency of the insecticide. Two insecticide products registered in North Dakota are dipel (Bacillus thuringienesis) and Insecto (diatomaceous earth). No-pest strips (dichlorvous impregnated strips, DDVP) can also be hung from the ceiling of grain bin during spring, summer and fall to deter any flying insects. Suspend one strip per 1,000 cubic feet of air space. These strips may need to be replaced every three months, especially during summer months.
Remember to monitor grains in bins for insect activity every two weeks when temperatures are above 55ºF. Stored grain insect pests are generally inactive at temperatures below 55ºF. If you find any insects, be sure to properly identify it. Knowing what insect species is infesting stored grain can provide important information on the grain condition and what the best curative or preventative action is. In short, stored grain insects can be thought of as very expensive, unwanted, tiny livestock!
Area Extension Specialist
North Central Regional Extension Center