Insect-feeding damage in the whorls and on small leaves of corn in south central Nebraska. (Photo by Jody Saathoff)

May 22, 2012

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Last week at Clay Center I noticed small beet armyworms feeding in the whorl and on leaves of small corn in some of my research plots. Jenny Rees, UNL extension educator, forwarded a report of corn earworms feeding in the whorl of corn in Frankliln County. I have not seen the caterpillar causing injury in Franklin County.

We occasionally see corn earworms feeding in whorl stage corn, but usually this occurs in mid-June, not mid-May. Beet armyworms are less commonly found in corn, but they have a very wide host range, including corn. They both would have similar damage symptoms in whorl stage corn; as the injured leaves emerge, there will be ragged holes in the leaves. This damage is usually not economically important.

Recommendations from other states suggest treating for corn earworms if 50-75% of whorls are damaged and caterpillars are still present. A variety of foliar insecticides would be effective. See the UNL Department of Entomology website for a list of products and rates.

Robert Wright
Extension Entomologist