MSU Weed Science - Department of Crop and Soil Sciences
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Aug 30th, 2015

MSUENT.COM
Field Crops Entomology Program
Michigan State University

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For MSU weed control information, visit our sister site, MSUWEEDS.COM
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Handy Bt Corn Trait Table - update for 2015

Keep track of Bt corn traits, efficacy, and refuge requirements for this season - print or download the handy Bt TRAIT TABLE, updated April 2015. This year, two separate versions of the table are available, for the northern U.S. and the southern cotton-growing region.

Corn rootworm resistance to Bt

Rootworm resistance to Bt corn has been confirmed in western states like Iowa and Minnesota, and in 2012/13 suspicious field failures were sampled in Michigan and New York. Bioassays conducted by colleagues in Ontario showed that rootworms from several of the Michigan fields survived hybrids expressing Cry3Bb1 or Cry3A Bts, a sign of resistance.

Now is the time to become familiar with the risk factors and symptoms of field failures, and to learn what to do about it. Entomologists from universities in the eastern corn belt (Purdue, MSU, Ohio State, Penn State, Cornell, University of Guelph) cooperated to develop a consensus recommendation for our region, which focuses on CROP ROTATION. Our goal is to preserve the usefulness of Cry3Bb1 and other rootworm Bts for you and your customers for as long as possible.

As the season progresses, please report suspicious fields immediately to Chris DiFonzo (517-353-5328 or difonzo@msu.edu), an MSUE agent, and to your seedsman. The faster people can visit a field, the better diagnosis we can make.

Learn more about the causes, identification, and management of Bt resistance:
**Updated in July 2015 - two page color handout with pictures on rating corn rootworm larval damage.
**Read the WHITE PAPER prepared and submitted to EPA by 9 entomologists in the eastern corn belt
**Download a four-page BULLETIN that summarizes our recommendation for producers