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From The University of Wisconsin-Madison/Extension
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Understanding Wisconsin FarmersÕ Bt Corn Insect Resistance Management Practices

Frederick H. Buttel

Department of Rural Sociology
Program on Agricultural Technology Studies and
Institute for Environmental Studies
UW-Madison
One of the conditions laid down by EPA as part of its approval of Bt crops was that farmers would be obligated to undertake insect resistance management (IRM) practices aimed at delaying or preventing insect resistance to various Bt toxins. Current IRM requirements for Bt corn are that (1) 20 percent of more of total corn acreage should be devoted to non-Bt corn ÒrefugesÓ; (2) Refuge corn may be planted in blocks or strips within a Bt-cornfield, or in a separate field that is within one half mile of oneÕs Bt corn; (3) Microbial Bt insecticides cannot be used on the non-Bt corn refuge; and (4) Other insecticides can be used to control corn borer or corn earworm on refuge corn only when Òeconomic thresholdsÓ are reached, as recommended by local or regional professionals (such as Extension agents or crop consultants). Estimating compliance with IRM practices is difficult for a number of obvious reasons. I will report results from a USDA-IFAFS-funded study of Wisconsin farmersÕ IRM practices. Data were collected by mail questionnaire from March through May 2002. Valid surveys were received from 52.1 percent of the sample of 1704. About 24 percent of the sample planted at least some Bt corn in 2001.
    Highlights of the results include:
  1. About 91 percent of Wisconsin Bt corn growers report that they are in compliance with IRM requirements (in response to a direct question about whether they have met all IRM requirements).
  2. Farmer responses to detailed questions about their corn management practices indicate that about 43 percent of Wisconsin Bt corn growers are not in compliance with at least one of the IRM requirements, suggesting a lack of understanding of IRM requirements.
  3. Farmers tend to find the 20 percent refuge and the Òeconomic thresholdÓ requirements the most troublesome to comply with; those who said the Òeconomic thresholdÓ requirement makes corn production Òmore difficultÓ were significantly more likely to be out of compliance with IRM than those who did not see this practice as a problem.
  4. Number of farm acres and farmer age were unrelated to IRM compliance.
  5. When respondents were asked about the IRM practices of neighboring farmers, about 32 percent of the respondents estimated that 50 percent of more of neighbors were not in compliance with RM requirements.
  6. IRM non-compliance by Wisconsin Bt corn growers appears to be considerably higher than in Minnesota, according to data collected by University of Minnesota colleagues involved in this IFAFS project.
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