Sweet Corn Insect Pest Summary

Bill Hutchison, Eric Burkness and Patrick O’Rourke, Entomology Department, University of Minnesota, St. Paul

Final graphs for the 2000 European corn borer (ECB) and corn earworm (CEW) moth flights are shown below. For much of southern Minnesota, and the possible exception of Blue Earth area, this was a fairly “typical” year for ECB. For CEW, this was another record year of moth pressure and challenges for managing the CEW successfully. The Blue Earth to Owatonna areas received some of the highest CEW pressure. However, even more moderate CEW flights at Rosemount resulted in >2.0 CEW larvae/ear in untreated check plots. By contrast, check plots at Rosemount usually averaged ca. 0.5 late instar larvae/ear. Although relatively less sweet corn production exists in west-central Minn., untreated check plots last week at the Morris Research and Outreach Station had over 7.0 CEW larvae/ear.

With a spring forecast for a slight risk of flea beetle (and Stewart’s Wilt) damage, due to the mild winter, there was some concern for damage in southern Minnesota (see May 19, 2000 issue: http://www.vegedge.umn.edu/mnvegnew/vol2/fb0519.htm ). However, to our knowledge, flea beetle infestations did not reach economically damaging levels. If growers did see damage that you suspect was Stewarts Wilt, please let us know (hutch002@tc.umn.edu).

Corn leaf aphid infestations were very high in some fields this year, typically from early tassel to silk. Although fresh-market growers are sometimes concerned with aphids as contaminants near harvest, we observed a high level of biological control by naturally occurring fungi and/or numerous predator species (especially lady beetles), that contributed to rapid reductions in aphid populations.

As the harvest season comes to a close, we hope that you will find a silver lining (i.e., net profits) in the ever-changing climate of risks associated with commercial vegetable production. With regard to the risk of yield or quality losses caused by insect pests, we hope that this newsletter has served as a useful early-warning system, and that this effort has been beneficial to your operation. In an upcoming issue, we will include a brief survey to request your feedback on what has been useful, and suggestions for future issues. Future fall/winter issues will also provide recent research updates such as insect control reviews for 2000, variety trial results, and meeting announcements.

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 Specialist, University of Minnesota, woldx018@tc.umn.edu

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Last Revised September 22, 2000.
The University, including the Minnesota Extension Service, is an equal opportunity educator and employer.©1999 Minnesota Extension Service, University of Minnesota. All rights reserved. Contact copyright@extension.umn.edu for information on reproduction or use of this material.