Feature Article: Vegetable Insect Pest Updates

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

European corn borer (ECB) and corn earworm (CEW) continue to be active in southern Minnesota (see Figs. 1-2, respectively). ECB moth catches have declined somewhat the past 5 days; we should be past the peak of the ECB flight. CEW counts continue to remain "moderate" at Rosemount (about 20/night), but still very high (>200/night) at the south-central sites of Rosemount and Blue Earth (Fig. 2). As cool fronts from the NW come in, this will help disrupt or delay more CEW flights (from the south); the cooler temperatures (day time highs in mid- to high 70s) provide some additional time for making treatment (spray) decisions for both pests.

All sweet corn in the late-tassel to first-silk stage should be receiving the first insecticide application. Timing of the first spray (for both pests) is the most critical for the entire ear maturation period. Following the first spray, 2 additional applications (for processing), or 3 additional sprays (for fresh market), at 5-7 day intervals, will usually provide excellent control. If the first spray is too late, subsequent sprays will not control larvae already inside the ear/husk. See the July issue, for more information on sweet corn insecticides.

In addition to sweet corn, bell peppers (all peppers) and snap (green) beans will also be attractive to ECB, and should be watched carefully. In particular, in the next 3 weeks, as sweet corn in your vicinity matures (brown silks), any pepper or snap bean fields that are still flowering will be VERY attractive to ECB, and also potentially VERY attractive to CEW (this year); CEW flights could continue to be heavy for another 2-3 weeks.

Cabbage looper infestations remain very heavy in our untreated (and some treated) cabbage plots at Rosemount! Additional sprays will be needed to protect all cole crops for another 2 weeks. We continue to see egg-lay, and young larvae getting established in our cabbage. Imported cabbageworm (butterfly) is also fairly light this year. You can view our best insecticide treatments at the Field Day, Aug. 22nd (see next article).

Aster leafhoppers are still active on carrots and lettuce; depending on projected harvest dates, one more spray for carrots may be needed, and 1-2 for lettuce, depending also on fresh market demands. Striped cucumber beetle, is interestingly ABSENT this year in MN; counts continue to be low, but watch for isolated hot spots building up in pumpkins, squash, etc. as they mature in the fall.

Finally, with this issue of the newsletter, we want to once again remind you of our Vegetable IPM Field Day, this coming Wednesday, Aug. 22nd, at the Rosemount Experiment Station (see next article, for the UPDATED PROGRAM; we have revised the program to now include LUNCH (burgers, brats, sweet corn), starting at 12:00 NOON to 1:30PM. In addition, we will now be giving away MN Twins and UofM Gopher Football Tickets! See you there!

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

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Last Revised August 15, 2001.
The University, including the Minnesota Extension Service, is an equal opportunity educator and employer.©2001 Minnesota Extension Service, University of Minnesota. All rights reserved. Contact copyright@extension.umn.edu for information on reproduction or use of this material.