We have previously reported on the existence of resistance in western corn rootworm populations in Nebraska to Cry3Bb1 and mCry3A proteins expressed in some Bt corn hybrids see website. Researchers led by Dr. Lance Meinke at the University of Nebraska-Lincoln continue to research this topic.
We cannot survey every location in Nebraska to determine the resistance status of rootworms in that area. However, growers can use information about their cropping history (rotational history, hybrid choice, and information about rootworm pressure in their fields) as a guide to selection of rootworm management practices. This topic will be presented at several Nebraska Extension Crop Productions Clinics see website in January 2016.
The National Corn Growers Association and The Agricultural Biotechnology Stewardship Technical Committee, a consortium of Bt corn registrants, have developed “Corn Rootworm Best Management Practices” available at here.
They recommend “to effectively manage corn rootworm (CRW), implement a multi-year plan that includes a variety of tactics” including crop rotation, hybrids with multiple CRW Bt traits, and soil-, seed- or foliar-applied insecticides.
They also ask growers to identify rootworm risk levels in their fields by answering these questions:
Did you plant corn rootworm traits for consecutive years in the same fields?
Did you notice large populations of corn rootworm beetles?
Did you observe root injury from corn rootworm larvae?
Are your fields planted to continuous corn?
Be thinking about these questions as you plan for the 2016 cropping season.