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Planting Season Is Topdressing Time

May 1, 2003
"April and May is planting season. Any big activities during those months will have to go on without me." Most people involved in agriculture probably have expressed similar sentiments to those demanding "other things" in April and May. Although planting season is a very busy time of year, it also is a very critical period for people who want to manage stored grain insects in corn that will be stored into the early summer. Taking a break from planting season to manage stored grain insects now can mean a lot of savings later.

Corn typically is safe from insect infestations if it is not stored past May or June following harvest. However, if corn is stored beyond June, you can count on infestations of stored grain insects. The management techniques required depend largely on how "summer bound" stored corn will be.

Corn to be stored for a long period of time after May or June requires early management and forethought because infestations likely will be evident deep in the grain mass by delivery time if the grain is not treated. After the corn becomes severely infested, it should be cleaned and sold as soon as possible. Cleaning may entail mild activity--pulling out a core of infested grain and delivering the salvaged portion--or fairly extreme activity--hiring a professional to fumigate the bin. Therefore, corn that will be stored for a long term should be placed in the bin only after old corn has been removed and the bin has been cleaned. Treating the bin with an insecticide may be needed to eliminate problems in hard-to-reach places. New corn that will be stored for a long time should be treated as it is augered into the bin. If these steps were not taken last fall for corn intended for long-term storage past May or June this year, you might want to reconsider the amount of time you store corn.

Corn to be stored for a short time after May or June likely needs only a topdressing of insecticide if sanitation and rotation were practiced. Materials such as Bt, pirimiphos-methyl (Actellic), or diatomaceous earth can be raked into the top 4 to 6 inches of the grain. Application time for those materials is April or May. These products are effective only against insects feeding at the grain surface (e.g., Indian mealmoth [the only stored soybean pest] and Angoumois [grain moth]). Those insects that feed beneath the surface will not be eliminated by topdressing. Taking the time to treat stored grain now is very important because a detection of surface feeders too late may require removal of webbed grain, followed by a topdress treatment or fumigation. Infested corn less than a year old often can be fed to livestock.

Applicators should always read and follow label directions, especially noting feed and delivery restrictions.--Matt Montgomery

Author: Matt Montgomery

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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