Many of today's genetically modified corn hybrids include one or more of the family of Bt proteins that protect the crop against corn rootworm and other lepidopteron pests. But rootworm resistance concerns have cropped up in several states, leaving farmers worried the effectiveness is waning.
Several agribusinesses have developed their own refuge strategies to ward off resistance. Now, the Environmental Protection Agency (EPA) has set a framework it says will delay corn rootworm resistance.
EPA cites the resistance “red zone” as portions of Iowa, Illinois, Nebraska, western Indiana, southwestern Wisconsin, southern Minnesota and eastern South Dakota. Regardless of geography, your farm could likely be in the red zone if the following is true:
- Continuous corn for multiple years
- Heavy use of Bt corn
- Regular rootworm infestations.
- Spotty compliance with current refuge requirements
The EPA framework for delaying further spread of resistance will require Bt corn manufacturers and farmers to do several things. First, in high-risk areas of rootworm resistance, the EPA will require crop rotation, use of corn varieties that have more than one Bt protein, or other IPM strategies and stewardship practices. Overall, EPA says 70% of corn acres in the red zone and 50% of all other acres should employ IPM efforts such as crop rotation.
Manufacturers will be required to develop and implement strategies to better detect and address new areas of resistance as they emerge. Also, the EPA says improved scientific tests and sampling methods are needed.
EPA officials say they are open to suggestions for alternative approaches. The agency has opened a comment period on this framework. Public comments can be submitted until March 16, 2015 to EPA docket EPA-HQ-OP-2014-0805 at www.regulations.gov.