In this issue:

Vegetable Insect Updates
*corn borer
*striped cucumber beetle
*aster leafhopper

Vegetable Insect Updates

Provided by Bill Hutchison and Eric Burkness, Department of Entomology, University of Minnesota

European corn borer: The first-generation ECB moth flight is underway in southern Minnesota. Based on current Degree-day accumulations (Rosemount, Dakota Co.), we are at approx. 33-50% emergence of the first flight (for typical 2-generation/yr borer). For a recent overview of (and graph) showing the predicted emergence curve for ECB, review the May 19, 2000 issue of this newsletter: http://www.vegedge.umn.edu/mnvegnew/vol2/ecb0519.htm

Corn Earworm: We have not yet collected any CEW moths in our pheromone traps at Rosemount. All processors and fresh-market growers should have 2 or more CEW traps placed in major production areas, to monitor early flights of CEW. Although our major flight in Minnesota does not occur until early August, we always catch some moths in June of each year. In some years these flights can be extensive. In 1999, an ‘Earlivee’ research plot, left untreated, resulted in an 85% ear infestation.

As part of a new grant from the Midwest Food Processors Assoc., Ken Ostlie, Hutchison and Burkness will be assisting growers/processors who wish to participate in an expanded CEW network. The long-term plan is that this will be coordinated like the ECB light-trap network, with CEW information provided in this newsletter as well as the BugWeb web site. For more information about your interest in participating in the network for 2000, trap use, etc., contact Eric Burkness (612-624-3670), or email: burkn001@tc.umn.edu

Striped Cucumber Beetle: Cucumber beetle counts declined this past week at our Rosemount location. No significant feeding damage has been observed on early-planted cucumbers, squash or pumpkin. Plantings should, however, be checked closely in the coming weeks, particularly for direct feeding damage on the cotyledon, or first true leaves. Young plants, for most varieties, cannot tolerate much direct feeding damage. Thresholds that justify insecticide use are 0.5-1 beetle/plant, or 10-15% defoliation (20-25% for 2nd true-leaf to flower). For more information see the Cucumber Beetle Fact Sheet: http://www.vegedge.umn.edu/vegpest/cukes.htm

Aster Leafhopper: Aster leafhopper have been common for the past 2-3 weeks in alfalfa and small grains (oats) (southeastern MN). They have likely been present in small grains used as cover crops for carrots. Recent counts in oats (Rosemount, MN) were 300/100 sweeps!

They are also common in Wisconsin, although not at these densities. We do not yet have estimates of aster yellows infection rates. Without this information, and in using historical early-season infectivity levels of 2.5-5%, the following thresholds can be used:

Pyrethroid insecticides (e.g., Asana or Baythroid, labeled for carrots) are necessary to provide longer-term residual control. For more information on all insect pest thresholds and/or current insecticide labels, see: Midwest Vegetable Production Guide-- 2000. (Edited by Vegetable Specialists in 5 Midwest States); includes insecticide, fungicide and herbicide label updates, recommendations for all major vegetable crop pests; updated annually. ($11.00 + shipping). To order, Call: 612-625-8173 (ask for publication # BU-7094-5).

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

Disclaimer
Reference to products in this publication is not intended to be an endorsement to the exclusion of others which may have similar uses. Any person using products listed in this publication assumes full responsibility for their use in accordance with current directions of the manufacturer

Last Revised June 7, 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.