Whorl-Feeding Caterpillars in Corn - UNL CropWatch, May 22, 2012

Whorl-Feeding Caterpillars in Corn - UNL CropWatch, May 22, 2012

Whorl feeding damage in corn Whorl feeding damage in corn
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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Corn earworm larva

Corn earworm larva (Photo by Jim Kalisch, UNL Department of Entomology)

 beet armyworm

Beet armyworm (Photo by Alton N. Sparks, Jr., University of Georgia, Bugwood.org)

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