Soybean Aphid Update, MN Insecticide Trial Results

Adapted from recent research provided by Drs. Dave Ragsdale and Ken Ostlie, Dept. of Entomology, University of Minnesota, St. Paul

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As many of you know, the soybean aphid, continues to do well in Minnesota, with infestations rapidly spreading westward. To date, most infestations continue to be limited to southeastern and south-central Minnesota, but isolated fields as far west as Lyon county were found on August 7th (Bruce Potter, IPM Specialist, Lamberton, MN). The following excerpt is taken from an Aug. 6th MN Insecticide Trial Report by Dave Ragsdale, Ken Ostlie and Erin Hodgson (full report available on the web at: http://www.soybeans.umn.edu)

Summary: "Nearly all registered products tested gave satisfactory control of the soybean aphid (see Table 1). Two compounds, Pounce and Dimethoate, significantly underperformed other products and provided only 85 to near 90% control of the soybean aphid. In general, 95% control or above is needed to prevent resurgence of the aphid population following treatment. As with all aphid control, better results are achieved with high pressure and high volume. Here, we used 42 psi and 30 gallons of spray solution per acre. An added advantage of our plots was the lack of a closed soybean canopy that allowed for good penetration of insecticide into the lower canopy. All products gave equivalent control of soybean aphids whether in the top or lower canopy We tested all products at the highest labeled rate. It is our opinion that those products that gave near 100% control could be used at the lowest labeled rate and still achieve satisfactory control (>95%). Good aphid control is less dependant upon rate than on using adequate spray volume (at least 20 gallons per acre) and high pressure (40-80 psi)". (see full report at: http://www.soybeans.umn.edu).

Editors Note: For updates on the management of soybean aphid in MN and the Midwest Region, refer to the following web sites:

MN Soybean Growers:
http://www.soybeans.umn.edu/crop_prod/insects/aphid/aphid.htm

MN Dept. of Agric. SA Monitoring Updates (check the latest 2001 report):
http://www.mda.state.mn.us/pestsurvey/PestReports/PestReport.html

Soybean Aphid in SW Minnesota: http://swroc.coafes.umn.edu/SWMNPEST/01news/issue15.htm

Michigan State 2001 Aphid Insecticide Trial Results:
http://www.msue.msu.edu/ipm/CAT01_field/FC07-26-01.htm#3

Wisconsin 2001 Aphid Insecticide Trial Results
http://ipcm.wisc.edu/wcm/pdfs/2001/01-20insect2.html

Midwest Region SA Distribution and Research Updates:
http://www.pmcenters.org/Northcentral/Saphid/aphidindex.htm

Co-Editors: Bill Hutchison, Department of Entomology, University of Minnesota, hutch002@umn.edu
Jeanne Ciborowski, IPM Program, Minnesota Department of Agriculture, jeanne.ciborowski@state.mn.us
Cindy Tong, Department of Horticulture, University of Minnesota, c-tong@umn.edu
Production Editor: Suzanne Wold, Graduate Research Assistant, Department of Entomology, University of Minnesota, woldx018@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 August 9, 2001.
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