In this Issue:
GUEST ARTICLE
Leaf Analysis as a Guide to Apple Orchard Fertilization
VEGETABLE NEWS
Vegetable Insect Update
Time to Watch for Squash Vine Borer and Squash Bug
STRAWBERRY NEWS
Strawberry IPM Update Plus Weather and Fruit Diseases
APPLE NEWS
Join us for the Upper Midwest Organic Tree Fruit Growers Network June Field Day
Weekly Trap Counts: June 6- June 15, 2005
| Vol 2 No.7 | June 20, 2005 |
Vegetable Insect Update
Eric Burkness and Suzanne Wold-Burkness, Dept. of Entomology, University of Minnesota
Cabbage Looper (CL): The first CL egg was found this week in transplanted cabbage near Rosemount, MN. Typically the cabbage looper flight does not begin until early July. However, because of recent weather events, it is possible that adults have been carried into the northern Midwest earlier than usual. We will continue sampling cabbage and will provide updates on CL infestations as well as catches from pheromone traps.
Treatment decisions should be based on 10% of the plants infested with CL larvae. Over the last five years imported cabbageworm (ICW) and diamondback moth (DBM) populations have been insignificant. However, if ICW and DBM were the dominant insect pests in your field, a threshold of 30% of the plants infested with larvae would be appropriate (as they do relatively less damage than CL).
Potato Leafhopper (PLH): Populations of PLH are increasing in snap beans, and have exceeded the threshold in our research plots at Rosemount. Thresholds for snap beans are 0.5/sweep for unifoliate to 2nd trifoliate stages, and 1/sweep for snap beans at 3rd trifoliate to bud stages. We have not yet found any PLH nymphs, however, we expect nymphs to be present in the next 1-2 weeks.
Striped Cucumber Beetle (SCB): SCB populations remain at approximately 0.5/plant at Rosemount. The particular field that is infested has been treated with Admire (in-furrow) insecticide. This is a relatively new insecticide for use against SCB, and we have a few field observations that might be helpful, if you are considering use of this insecticide. It appears that beetles will infest the field and cause minor feeding damage before the insecticide takes effect. One to two days after infestation we observed beetles that were alive, but not feeding, and appeared to be dying. Three to four days after infestation dead beetles were present in the field. Despite SCB populations of 0.5/plant, feeding damage was relatively minor throughout the field.
Bean Leaf Beetle (BLB): We continue to see relatively high levels of BLB in our snap bean plots. Untreated check plots have either been killed or the defoliation level exceeds 90%. Despite the high level of damage in snap beans, populations appear to be declining (0.33/plant, down from 0.75/plant). We would expect the overwintering population of BLB to decrease substantially by the end of June and the 1st generation adults to begin emerging by mid July.
European Corn Borer (ECB): Catches of ECB in blacklight traps remain very low across the Minnesota. Current degree-days at Rosemount are 691 (base >50°F). This puts us past the peak of the 1st generation flight, which occurred at approximately 600 degree-days. ECB catch has reached 5/night in St. James (Watonwan Co.) and 3/night in Rosemount (Dakota Co.) (see graph).
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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