In this Issue:
**WEB ONLY VERSION**
"Limited" Corn Earworm Alert for Southern Minnesota
| June 30, 2005 |
"Limited" Corn Earworm Alert for Southern Minnesota
Bill Hutchison, Dept. of Entomology, Univ. of Minnesota
Because of the July 4th Holiday, we will not have a MN Fruit & Veg. IPM Newsletter this week. Occasionally, when we take a newsletter break, the bugs do not cooperate.
Today's Pest Alert concerns recent increases of Corn Earworm (CEW) moth catches, primarily at Rosemount (Dakota Co.). Although most other sites in MN have reported only 1-2 moths/night, the recent increases at Rosemount, to 7/night yesterday (Hartstack, wire-mesh, pheromone trap; see trap pictures, below), indicate that CEW females are present and will be attracted to fresh-silking sweet corn in the area. As you may know, CEW lays its eggs directly (singly) on the silks of developing ears. Infestations left untreated will result in one-inch long worms, approx. 25 days after egg hatch. At least for the Rosemount location, 7/night is over the nightly thresholds (see 2003 article below). Most of our MN sites, as of yesterday, were still showing only 1 moth/night, thus infestations right now may be locally variable. Note: if you have access to blacklight trap data, and these traps are catching just 2-4 moths/night, that is also an indication of significant CEW activity.
Why now?
CEW is one of several pests that does not overwinter in MN but migrates north each year from the Gulf Coast states. Although this flight is earlier than the average late-August flight (as per 2004), we still have approx. a 20% chance of CEW arriving in June or July, and affecting early-planted sweet corn. We have had several Low-pressure systems over the past 10 days that are conducive to transporting CEW (as well as potato leafhopper).
What to do?
IF you do not have sweet corn silking this week, then your crop is not at risk; enjoy the holiday. If you do have sweet corn silking, or just beginning to silk, growers who have traps should be checking these now. If you do not have traps out, check the silks for the presence of eggs to verify the start of an infestation. You can also check our CEW trap catch data for several areas in MN, and for Madison, WI at the CEW Moth site: For more information on Traps, Thresholds, Labeled Insecticides, see the 2003 article at: |
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| Cloth "Scentry Trap" | Metal "Hartstack Trap" |
ACKNOWLEDGEMENTS
Co-Editors: Bill Hutchison (hutch002@umn.edu), Department of Entomology, University of Minnesota, Jeanne Ciborowski, Minnesota Department of Agriculture, Ag. Resources Management and Development Division, and Suzanne Wold-Burkness (woldx018@umn.edu), Department of Entomology, University of Minnesota
The Newsletter is published weekly from May through August, cooperatively, by the Minnesota Department of Agriculture (MDA) and the University of Minnesota (U of MN). Reports are posted on the U of MN and MDA web sites on Fridays. If you have suggestions and/or comments, please send your contributions by 4 p.m., Wednesday to Jeanne Ciborowski, 651-297-3217, jeanne.ciborowski@state.mn.us , MDA, 90 W. Plato Blvd., St. Paul, MN 55107-2094. You can access the Newsletter at the U of MN web site in htm format at: www.vegedge.umn.edu/MNFruit&VegNews/mnindex.htm and at the MDA web site in pdf format at: www.mda.state.mn.us/biocon/fruitreports/
Partial funding for this publication is provided through partnership agreements with the Minnesota Fruit and Vegetable Growers Association (MFVGA) and the United States Department of Agriculture – Risk Management Agency (RMA). These institutions are equal opportunity providers.
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