Alfalfa Weevil Scouting in 2010

May 3, 2010

By Adam Sisson, Corn and Soybean Initiative and Erin Hodgson, Department of Entomology

NOTE: This article was retracted on May 4, 2010 - due to new information and data. See the correction article.

Now is the time to scout for alfalfa weevil larvae in most crop reporting districts in Iowa. The scouting threshold has not yet been reached for northern and west central districts of the state but scouting dates are coming up quickly.

Growers in the southern three districts should start scouting for larvae at 200 growing degree days (using a base of 48 F), while those in the central and northern regions should start scouting at 250 growing degree days. This means that growers should presently be scouting fields in southern and most of the central districts of the state. Scouting for larvae should begin May 4 in the west central district and May 7 for all three northern districts of Iowa (Figure 1).
 
alfalfa weevil scouting date map

Figure 1. Alfalfa weevil scouting dates and accumulated growing degree days (using a base of 48 F) in Iowa from Jan. 1 to May 2, 2010.

Scouting, identification and economic thresholds for treatment of the alfalfa weevil are explained by Marlin E. Rice in a past ICM Newsletter article.

 

Adam Sisson is a program assistant with responsibilities with the Corn and Soybean Initiative. Sisson can be contacted by email at ajsisson@iastate.edu or by calling (515) 294-5899.  Erin Hodgson is an assistant professor of entomology with extension and research responsibilities. She can be contacted by email at ewh@iastate.edu or phone (515) 294-2847.

Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on May 3, 2010. The information contained within may not be the most current and accurate depending on when it is accessed.

ICM News
Authors: 

Adam Sisson Extension Program Specialist III

Adam Sisson is an extension specialist with the Iowa State University Integrated Pest Management (IPM) program. Sisson focuses on the development of publications and other educational resources for farmers, agribusiness, and students. He receive...

Erin Hodgson Associate Professor

Dr. Erin Hodgson started working in the Department of Entomology at Iowa State University in 2009. She is an associate professor with extension and research responsibilities in corn and soybeans. She has a general background in integrated pest management (IPM) for field crops. Dr. Hodgson's curre...