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Watch Soybean Aphid Numbers - NOW

Jon Tollefson, Department of Entomology

Last week the conditions in Minnesota were very good for soybean aphid reproduction. With those conditions, the populations increased rapidly in many locations throughout Minnesota. We have been expecting 2008 soybean aphid populations to be lower as they were in 2004 and 2006, but the 2008 weather has not been exactly “typical.”

The increase in aphid numbers in states north of us serves as a reminder that this is the time you must be scouting soybeans to avoid an outbreak of aphids in any of your soybean fields.

For some helpful reminders, the treatment threshold for soybean aphids should remain at an average of 250 aphids per plant, even with increased value of soybeans as discussed in an Integrated Crop Management article released today.

The scouting technique to monitor aphid numbers was described in an Integrated Crop Management article in July of 2007.  There is a faster, binomial method to make an aphid management decision in soybeans. The “Speed Scouting” technique is described in the article as well; additional information is available from the University of Minnesota.  A free quick field guide to using this method can be ordered from Iowa State University Extension. 


Jon Tollefson is a professor of entomology with extension and research responsibilities.


This article was published originally on 7/30/2008 The information contained within the article may or may not be up to date depending on when you are accessing the information.

Links to this material are strongly encouraged. This article may be republished without further permission if it is published as written and includes credit to the author, Integrated Crop Management News and Iowa State University Extension. Prior permission from the author is required if this article is republished in any other manner.