In this Issue:

VEGETABLE NEWS

Vegetable Insect Update

Food Alliance Certification and Treatment Thresholds

APPLE NEWS

Key Apple Pests of Concern during the Summer and Fall

Minnesota Grown Program 2005

Weekly Trap Counts: July 5 - July 14, 2005

Apple Scab Infections

Insect, Pest Fact Sheets

Vegetable Insect Pest Update

Bill Hutchison, Suzanne Wold-Burkness, & Ted Galvan, Dept. of Entomology, University of Minnesota, St. Paul

True Armyworm (TAW): With recent southern Minnesota trap catches exceeding 100-200 moths per night, the last week of June, there have been a few reports of armyworm feeding damage on whorl-stage sweet corn (e.g., near Hastings). Sweet corn fields should be monitored for early stage larval feeding damage (see photo, below).

Although we have not conducted research with armyworms on sweet corn, there seems to be a consensus in the Atlantic coast states, for whorl stage sweet corn, of an action threshold of 15% of the plants infested. The following is a quote from Dr. Shelby Fleischer's sweet corn fact sheet on the topic:

“Vegetative corn" should be scouted, and the percent of infested plants estimated. We can tolerate 15% infestation, and up to 30% on larger, longer-season varieties, before a spray on vegetative corn is warranted. If infestation rates are low, try waiting until the "row-tassel" stage (when you can look down a row and just begin to see the tassels emerge). A single spray timed at row tassel will clean up low infestations prior to the corn moving into the reproductive stages, saving earlier sprays applied to vegetative corn.”

For more recent information about the true armyworm in Minnesota , see the recent article by Ian MacRae, Dept. of Entomology, UM, located at UM-Crookston: http://www.nwroc.umn.edu/ent/redent.html

Potato Leafhopper (PLH): In snap beans planted May 23^rd, PLH nymphs have increased to 1.8/leaflet. At 0.3 nymphs/leaflet, plots that were treated previously with foliar insecticide applications (pyrethroids) continue to be below the threshold of 1/leaflet. Snap bean fields that are still 2 weeks from harvest and have high PLH infestations should be treated to preserve yields.

Cabbage Looper (CL): We continue to catch low levels of CL moths in pheromone traps. Therefore, field monitoring should continue using the threshold of 10% of the plants infested with CL larvae.

European Corn Borer (ECB) and Corn Earworm (CEW): ECB and CEW moth catch remains low. However, as early planted sweet corn approaches the silk stage, catches from both pheromone and blacklight traps should be monitored closely to detect any sudden increase in moth catch.

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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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