MN Fruit & Vegetable IPM News - Vol. 5, No. 7

Pest pressure and the growing season are finally beginning to pick up this year. Recently, there have been few insect pests detected in samples of snap beans, cabbage or cucurbits. However, this week, in the Rosemount, MN (Dakota Co.) area, transplanted cabbage (heading) and seeded cabbage (cupping) had a small infestation of diamondback moth (DBM) and cabbage looper (CL) larvae with 5% of plants infested with each pest. DBM infestations have been present for a week or two but the CL infestation is a little earlier than normal. We typically don’t see CL moths reaching central MN until the first week of July. The CL was newly hatched and no CL eggs were detected so this may be an isolated early find.

At the end of last week, the first striped cucumber beetles (SCB) of the season were found in a pumpkin field near UMORE Park in Rosemount, MN. Pumpkins were at 2 true leaves and there were 0.5 SCB/plant, mainly limited to the edge of the field. This week populations have exploded and pumpkin fields near UMORE Park are anywhere from 2 SCB/plant to greater than 5 SCB/plant. The high for one of the fields was 54 SCB on a single plant. The plants were anywhere from 4 – 7 true leaves and this infestation level is certainly one that would require treatment (see the SCB profile for thresholds and management options).

Snap beans have remained relatively pest free this season as well. However, low potato leafhopper (PLH) and bean leaf beetle (BLB) infestations have finally been detected in snap beans. Snap beans that were at the flower bud stage to open flower had infestations of 0.16 PLH / sweep, well below the treatment threshold of 1/sweep. BLB was at 0.04/sweep. Younger snap beans at the 1 – 2 trifoliate stage were not infested with PLH or BLB.

European corn borer (ECB) is finally being caught with some regularity in black light traps in the state but at low levels (see Figure 1). As of June 23, we are at 602 degree days (base 50°F). The average degree day requirement to reach the peak of the first generation ECB moth flight is at 631, so the peak ECB flight should have occurred sometime this past week. We’ll have to wait and see what impact the early season conditions have had on the second generation ECB flight. Cooperators in MN using pheromone traps to monitor corn earworm (CEW) have started catching and reporting trap catches (see Figure 2). However, this early season CEW activity is typically much lighter than the mid August activity and and it is unlikely there are many sweet corn fields that are highly attractive, in terms of late whorl to silking plants.

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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, 651-201-6217, jeanne.ciborowski@state.mn.us , MDA, 625 Robert St. North, St. Paul, MN 55155. 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/plants/pestmanagement/ipm/ipmnews.htm

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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Last Revised May, 2008 by woldx018@umn.edu
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