In this issue:

Sweet Corn Insect Pest Update

Bayer to Phase out Guthion

National Organic Program

Corn Smut Hits Again

Rootworm Beetles Feeding on Silks

Squash Bug Populations Increasing

Rootworm Beetles Feeding on Silks

Eric Burkness and Bill Hutchison Dept. of Entomology, University of Minnesota

As field corn silks continue to dry down, late-planted sweet corn, which is silking, has become very attractive to both northern and western corn rootworm adults. When fresh silk is present beetles will feed on the silk, which can lead to poor pollination. With heavy infestations corn rootworm adults will begin to feed on corn leaves and tassels (see photos). As shown in this phot, significant leaf feeding is also occurring at this time. In sweet corn where insecticide applications have been made to control European corn borer (ECB) and corn earworm (CEW), corn rootworm infestations should not be of concern. However, in late-planted sweet corn where insecticide applications have not been made, or in sweet corn varieties expressing Bt, corn rootworm populations should be monitored (see August 26, 1999 issue).

If adult corn rootworm populations exceed 5 beetles/ear and there can be significant silk clipping (>10% of ears), then insecticide application should be considered. For more information on insecticide options for corn rootworm control, see the August 26, 1999 issue.

Adult corn rootworms, Rosemount, Aug. 22, 2002

Ear showing poor pollination due to silk clipping (John Wedberg, Univ. of Wisconsin)

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Co-Editors: Bill Hutchison, Department of Entomology, University of Minnesota, hutch002@tc.umn.edu
Jeanne Ciborowski, IPM Program, Minnesota Department of Agriculture, jeanne.ciborowski@state.mn.us
Cindy Tong, Department of Horticulture, University of Minnesota, ctong@extension.umn.edu
Production Editor: Suzanne Wold, Research Assistant, University of Minnesota, woldx018@tc.umn.edu

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Last Revised August 23, 2002.
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