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Issue No. 3, Article 1/April 10, 2009

Bt Refuge Compliance: Grower Stewardship Vital to Maintain Durability of This Technology

As the percentage of Bt stacked corn hybrids continues to increase significantly across the Corn Belt, it will become even more important for growers to implement refuges according to prescribed guidelines. Even though there has been considerable discussion and debate about the merits of the "refuge-in-the-bag" concept, this resistance management strategy has not been approved for the 2009 growing season. At the 2009 Corn and Soybean Classics meetings, we asked producers (utilizing Turning Point Technology to gather responses) to describe their level of refuge compliance in 2008. According to their anonymous answers, 83%, 85%, 85%, 85%, 76%, and 76% of those responding in Mt. Vernon (n = 87), Champaign (n = 124), Bloomington (n = 110), Springfield (n = 161), Moline (n = 90), and Malta (n = 88), respectively, who planted a Bt hybrid in 2008 implemented a 20% refuge according to recommended guidelines. This represents an overall 82% refuge compliance rate for the 660 producers who responded to this question.

Although the great majority of producers are to be credited for their stewardship of this technology, many thousands of acres that should have been devoted to a refuge were not. The escalating use of Bt hybrids, even on those acres with very low pest densities, along with the lack of refuge compliance on some farms will heighten the selection pressure for resistance development by European corn borers and/or corn rootworms. Also, it is important to remember that each kernel of Bt seed is treated with a neonicotinoid (clothianidin and/or thiamethoxam) insecticidal seed treatment. By planting Bt seed, producers are placing selection pressure on many secondary insect populations (seed corn maggots, white grubs, wireworms) that may also develop resistance to this important class of insecticides.

If you planted a Bt hybrid in 2008, did you plant a 20% refuge according to the suggested guidelines?

On August 14, 2008, the USDA's Federal Crop Insurance Corporation (FCIC) board of directors approved premium rate reductions for producers who use selected "seed technologies" during the 2009 growing season. A list of corn hybrids that qualify for this program can be found at the following website: www.rma.usda.gov/news/2008/08/fcicbiotech.html. This approved list is conditional and requires the applicant's cooperation with the Risk Management Agency "to develop a single unified biotechnology endorsement and work out associated details."

The following seed technologies were approved by the FCIC board for Illinois: YieldGard Plus with Roundup Ready Corn 2, YieldGard VT Triple, YieldGard VT Triple PRO, Herculex Xtra, Herculex Xtra RR2, Agrisure CB RW (stacked), and Agrisure 3000GT hybrids. Producers are encouraged to go to the website for additional details concerning eligibility requirements. According to the guidelines, "insured producers will be required to purchase a buy-up level of coverage and plant at least 75 percent of their insured corn acres in a unit to a qualifying corn hybrid."

When we asked producers at the 2009 Classics whether a similar USDA crop insurance program influenced their decision to plant a Bt hybrid in 2008, a majority (an average of 82% of producers across the six locations) said no. The number of respondents in Mt. Vernon was 86; Champaign, 123; Bloomington, 120; Springfield, 157; Moline, 92; and Malta, 91.

Has the USDA decision to provide reduced crop insurance premiums for producers who plant Bt hybrids influenced your decision to use a Bt hybrid?

We look forward to the upcoming growing season and encourage producers to implement refuges according to prescribed guidelines. Producers who detect unusual levels of insect damage (root injury or stalk tunneling) to Bt hybrids this season should be sure to contact their appropriate seed company representative and/or university entomologist.--Mike Gray

Mike Gray

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