Scientific advisory panel makes recommendations on optimum acre-max seed blend refuge

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.   

The final report from the Scientific Advisory Panel (SAP) reviewing the Optimum Acre-Max seed-blend rootworm refuge is publicly available. The Panel was made up of scientists with expertise in genetics, entomology, integrated pest management (IPM), crops, toxicology, and environmental issues. They reviewed an application from Pioneer to blend a approximate 2 percent refuge (non CRW seed) with Herculex Xtra. The purposes of the seed-blend were to reduce the current 20 percent CRW refuge for Herculex CRW corn and to increase grower compliance.

The Panel identified many “areas of uncertainty” (technical stuff related to the toxin, beetle genetics, and biology) such as mode of action of the Bt toxin, mortality of susceptible & heterozygous beetles, implications of delayed adult emergence and uneven sex ratio on development of resistance, frequency and type of resistance genes in the CRW population, the physical mechanics of mixing seed to achieve a certain percentage and the distribution of non-GMO plants in the field.

While the Panel supported the concept of a seed blend in general for CRW, they found no evidence to reduce the refuge percentage. Quote - “In general, the Panel concluded that there are uncertainties with the use of a seed blend and clear problems with reducing the refuge size. The Panel recommended additional research that would more completely examine the performance of the seed mix strategy”.

The Panel found “…no compelling evidence to reduce the proportion of non-Bt plants (either as a seed blend or spatial refuge) from 20 percent and there was strong concern with the request for any reduction in the refuge size with a seed blend of 5 percent or less. Data were not presented that supported a claim that potential yield losses justify a seed blend of no greater than 5 percent....Therefore the Panel concluded that, based on current science, it would be reasonable to commercially use 20 percent seed blend refuges, while research suggested by the committee and research projects are conducted to example performance of the seed blend strategy.”

The Panel is only advisory to EPA, but its recommendations carry weight.

In a related issue, the Panel received an anonymous statement from 26 university corn entomologists raising a concern about company restrictions on university research using commercially available GMO seed. The Panel specifically commented on this statement: “ …in response to two public comments, several panel members believed that access to transgenic plants by qualified researchers must be more open and transparent to maximally foster resistance management research. It does not reflect well on the biotech industry, nor does it help researchers achieve further advances in resistance management, to restrict research by public sector researchers to plant varieties that can be purchased in the open market.”

For those of you want light weekend reading, below is a link to the EPA web site with the report. Under final meeting minutes, click on the pdf icon to open the minutes.

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