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United States Department of Agriculture

Agricultural Research Service

Title: Refuge Issues

Author
item Hellmich, Richard

Submitted to: Proceedings of EPA/USDA Workshop on Bt Crop Resistance Management
Publication Type: Proceedings
Publication Acceptance Date: September 1, 1999
Publication Date: N/A

Technical Abstract: The NC205 committee formally addresses research on the "Ecology and Management of European Corn Borer and Other Stalk-Boring Lepidoptera." For the past four years this committee has sponsored six meetings with seed corn companies, gene suppers and the Environmental Protection Agency (EPA) to discuss insect resistance management (IRM) issues. Refuge is critical for IRM because it produces susceptible insects that, if present in sufficient numbers, will mate with resistant insects and dilute out resistance genes. As of May 1999, the NC205 recommendation for refuge size for most of the Corn Belt is 20%. This recommendation applies to areas where up to 25 percent of the acres are sprayed for European corn borer over a large area, for example parts of Nebraska. Proximity of refuge is also an important consideration. Refuge must be close enough to Bt corn so that susceptible moths will randomly mate with potential resistant moths. Our current recommendation is that planting schemes which place all Bt cor within one half mile of the nonBt corn refuge are preferred and refuge plantings within one quarter mile would be even better. However, we understand that this is not always possible, for example, unusual field configurations, can create problems. We realize that refuge deployment will vary from farm to farm. Growers will have to consider the equipment he or she has, and their field arrangements. Giving the grower flexibility in this area is important. In general, we highly discourage seed mixtures, strips are fine, and blocks, as long as they are within a 1/2 mile, are also fine.

Last Modified: 4/16/2014
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