Christina DiFonzo, Michigan State University field crop entomologist, has major changes to the Handy Bt Trait Table updated for 2018. To improve readability, trait packages are now alphabetized instead of grouped by seed company. Also, letter abbreviations for insect names and herbicides were replaced with simple “X’s.”
Last year, DiFonzo added an “ineffectiveness” column listing insect x Bt combinations with field-failures, confirming resistance or cross-resistance in lab assays of the field. For 2018, this column has the same format, but DiFonzo relabeled it “Resistance to a Bt protein in the trait package has developed in.” This column is intended to track cases of resistance development to Bts, plus 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. Since the Trait Table is a national publication, check with your local Extension educators and seed dealers to determine the status of Bt resistance in your local area.
Note that based on overwhelming evidence from lab assays and the field, companies 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. She will give the seed companies credit for making this change to reflect the reality that they've seen in Michigan and surrounding states.
DiFonzo realizes that the updated table does not include the new Enlist (2-4D tolerance) trait. She will be working to incorporate that into the table next season.
Access the updated for 2018 table at: Handy Bt Trait Table for U.S. Corn Production.