In this Issue:
VEGETABLE NEWS
Vegetable Insect Pest Update
STRAWBERRY NEWS
APPLE NEWS
Elm Tree Farm Hosts Organic Apple Field Day
Note: There will be no Newsletter next week. We will return August 8th.
| Vol 5 No. 9 | July 25, 2008 |
Vegetable Insect Pest Update
Eric Burkness and Bill Hutchison, University of Minnesota
As we move in to the middle of the growing season and crops are starting to flower and fruit, it has been a relatively uneventful year for insect pests on most vegetable crops. This week, in the Rosemount/Apple Valley, MN (Dakota Co.) area, transplanted cabbage (heading) was being harvested and seeded cabbage (heading) is close behind. Imported cabbage worm (ICW) and cabbage looper (CL) have been almost non-existent in cabbage fields and diamondback moth (DBM) was present in low numbers earlier in the season. A somewhat unusual pest in cabbage this week included grasshoppers (several species) that emerged in a grassy strip along the field edge and moved in to the 1st 50 feet of the field and to feed on the wrapper leaves of the cabbage head. The damage looks very similar to the usual larval pests but the frass is dry and made up of very small granules, unlike ICW or CL frass that is very moist and more pellet sized. We are not aware of a threshold for grasshopper on cabbage but a maximum of 10% of heads with damage during heading to harvest is probably reasonable. The grassy strip had a grasshopper population of 2.5 per sweep. In this situation, isolating the treatment area to the edge of the field worked well.
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Striped cucumber beetles (SCB) continue to be found in pumpkin (vine to flowering) and cucumber (flowering) fields near UMORE Park. Now they are primarily feeding in the large blossoms of pumpkin. Recently, the emergence of northern corn rootworm has started and with the delayed development of corn silks, they are moving into the pumpkin flowers as well (see the SCB profile for thresholds and management options). Potato leafhopper (PLH) numbers in alfalfa in the Rosemount area have remained low at about 0.25 per sweep in the 6 inch re-growth from the 2ndcutting. Not surprisingly, PLH numbers in snap beans (pin beans – mature beans) have also remained low at 0.04 per sweep. Black light trap catches of European corn borer (ECB) continue at low levels across the state (see Figure 1). As of July 21st, we are at 1200 degree days (base 50°F), which should be past the treatment window for 1st flight ECB larvae and we should start to see the 2nd flight begin at about 1400 degree days. Pheromone trap catches for corn earworm (CEW) continues to remain low in MN (see Figure 2), and current High pressure systems over the upper Midwest will limit moth migrations north. We typically expect significant flights of CEW in MN to begin in early to mid August. |
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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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