Corn rootworm larval damage has been suspected or confirmed in Wisconsin corn fields planted to Bt CRW hybrids. This has prompted concern among crop advisors regarding recognition, severity and distribution of the problem. To help answer these concerns, a survey was conducted to evaluate corn rootworm larval damage to Bt CRW hybrids. Cooperators were asked to submit five (5) corn roots/field that were at least second year corn and planted to a Bt CRW hybrid. Field background requested from each field included, county, hybrid and Bt event. There were no attempts to single out commercial hybrids or Bt events. Approximately 110 fields were surveyed in 18 counties (Fig. 1). Range of fields sampled/county were from 1 to 21.
Soil Science Extension
University of Wisconsin Madison