Corn earworm (Photo 1) is common in Iowa corn. It is a migratory pest, migrating from the southern and southeastern U.S. every summer. There are two general fights to the Midwest every summer, but the first flight is not of economic concern. Iowa’s corn is more vulnerable to infestation of the second flight, arriving in late July. Yield losses can occur in late-planted cornfields, where caterpillars can infest >50% of plants. It is more common to see corn earworm issues in sweet corn, white corn, popcorn, and seed fields. Kernel injury can promote ear mycotoxins (e.g., fumonisins and aflatoxins) and further reduce grain quality. The frass (excrement) can also be a contaminant for corn processing.
Iowa State University
Hodgson, Erin W., "Corn Earworm Picks up Activity in Iowa" (2019). Integrated Crop Management News. 2583.
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