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Issue No. 2, Article 3/April 1, 2005

Iowa State University Entomologists Publish Survey Results on "Practices and Perceptions" of Farmers Regarding Transgenic Corn

In the most recent issue of the Journal of Economic Entomology (Volume 98, pages 237-247), entomologists from Iowa State University have provided a summary of survey results that were collected in 2001. The questionnaire (self-administered) was sent to 5,000 producers in Illinois, Indiana, Iowa, Minnesota, and Nebraska. A total of 1,313 (26.3%) surveys were returned: Illinois (257), Indiana (251), Iowa (284), Minnesota (265), and Nebraska (256). The results of the survey reveal some interesting perceptions of producers with regard to the use of transgenic hybrids to control European corn borers and corn rootworms. When interpreting these data, keep in mind that the survey was conducted at a point when producers had had an opportunity to use Bt hybrids for European corn borers for about five growing seasons, and transgenic hybrids for corn rootworms were still 2 years from the marketplace.

As of 2001, a great majority of producers (75.2%) still relied on crop rotation as their primary management tactic for corn rootworms. Soil insecticide use on first-year corn was heaviest in Illinois and Indiana, with 33.5% and 39.4% of producers, respectively, treating rotated corn due to concerns about the variant western corn rootworm. Regarding producer interest in using transgenic hybrids for corn rootworm control, 35% of the respondents indicated they would use this new technology.

The two key issues that concerned pro-ducers about the use of transgenic hybrids for corn rootworm control were marketability of the grain (59.3%) and the payment of a technology fee (54.8%). The most important pluses that farmers perceived relative to the use of transgenic hybrids were reduced exposure to insecticides (69.9%) and environmental benefits (68.5%).

Approximately 25% of producers with large farms (>520 acres) indicated that one of the primary benefits of using transgenic hybrids is the potential elimination of scouting. The authors of the paper expressed discouragement over this finding and pointed out that scouting fields is a key component of IPM programs. As discussed many times in the Bulletin, transgenic hybrids for corn rootworms can be deployed in fields that are most likely to benefit from this protection based on scouting input from the previous season. In addition, in many areas of Illinois, European corn borer densities are very low.

For a complete discussion and analysis of the fall 2004 European corn borer survey, please refer to issue no. 24 of last season's Bulletin (November 5, 2004). Because densities of European corn borer are so low, producers should be reminded that planting a non-Bt hybrid remains an option. This assumes that farmers will scout fields for the first and second generation of this insect pest and will apply rescue treatments as needed based on economic thresholds. Don't forget to "dust off" these IPM practices and use them as appropriate. The "I" in IPM is very important. An overreliance on any single pest management tactic will have unfortunate consequences at some point.--Mike Gray

Mike Gray

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