No. 15 Article 4/July 2, 2004

European Corn Borer in Northern Illinois

Little has been mentioned yet this summer about European corn borer infestations. Reports filter in every now and again concerning small corn borer infestations around the state. Last week, Russ Higgins, an IPM Extension educator at the Matteson center, and Gary Bretthauer, a unit educator in Kendall County, found an average of 40% of plants infested with corn borer larvae in a few fields they checked. Dave Feltes, an IPM Extension educator at the Quad Cities center, found approximately 30% of plants infested with corn borer larvae in a field in Whiteside County. I also had the opportunity to look into some fields in northwest Illinois over the weekend and found much of the same. Most fields I looked at had anywhere from 20% to 50% of plants exhibiting larval feeding, with two to five larvae per plant. Larvae were first and second instars feeding in the whorls.

Kelly Robertson, CCA, reported finding several instances in Franklin County where corn plants are starting to break off where larvae have tunneled low in the plant. In corn nearing tassel, as many as three tunnels per plant--one about one joint above the ground, one at the ear leaf, and one about two or three joints down from the top--were found.

Image of European Corn Borer tunneling
European corn borer found tunneling in plant (Photo courtesy of Kelly Robertson).

While southern Illinois is nearing the end of first generations and beginning to gear up for second-generation moth flights, those in the northern part of the state are in the middle of first-generation feeding. If you have the opportunity, stop and take a look at your fields. Once corn borers begin to tunnel in the cornstalk, rescue treatments are no longer a viable control option. More information on the European corn borer can be found on the IPM web site. --Kelly Cook

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