Negotiate the Bt Maze

Pamela Smith
By  Pamela Smith , Crops Technology Editor
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It’s never been more important to understand the combinations of corn traits being planted. The 2018 Handy Bt Trait Table is designed to help growers do a better job of rotating traits.

Michigan State University entomologist Chris DiFonzo updates this invaluable reference tool each year. Find it at This year, trait packages are alphabetized instead of grouped by seed company.

A column that tracks cases of resistance development to Bt proteins is an effort to alert producers and consultants to potential management problems. Depending on the insect, resistance may be widespread, as in western bean cutworm, or regional, as in corn rootworm.

The Trait Table is a national publication, so it’s important to check with local Extension educators and seed dealers to determine the status of Bt resistance in your local area.

Based on overwhelming evidence from lab assays and the field, companies have now removed western bean cutworm control from Cry1F Bt hybrids. Only hybrids with the Vip3A Bt protein provide reliable control of this insect. For all other hybrid packages, western bean cutworm infestations should be managed using a combination of scouting and spraying at threshold, DiFonzo explains.

The updated table does not include the Dow Enlist trait package that will commercially debut in 2018. Enlist corn with herbicide tolerances to 2,4-D choline, glyphosate and FOP herbicides will be stacked with either SmartStax or Powercore corn trait technologies.


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