To date, data from South Dakota indicates that Bt-corn fields are showing unexpected corn rootworm damage in the vicinity of Lake Campbell, Bruce, Milbank, Baltic, and Colman, reports Ada Szczepaniec, Assistant Professor and SDSU Extension Entomologist in a recent article.
"It should be noted that not all problem fields are reported; therefore, it is difficult to quantify whether these are isolated instances or represent a potential broader scale occurrence," Szczepaniec said. "In those fields that have been investigated, resistance to Bt hybrids has not been confirmed yet, and we will work to collect data to test this next year."
She adds that fields with a history of at least three years of continuous corn with the same Bt hybrid are at the greatest risk of having Bt-resistant populations of corn rootworms.
"Corn rootworm issues in fields planted with Bt-corn hybrids have been getting a fair amount of attention in the Midwest and Northern Plains. Because South Dakota has a substantial diversity of soil types and growing conditions, it is likely that the severity of corn rootworm issues varies significantly within the state," she said.
Szczepaniec calls upon South Dakota corn growers to help collect the needed data by filling out a short, Online survey which SDSU Extension staff will use to develop research-based recommendations to aid the state’s corn growers deal with this pest.
"The survey will take only a minute or two to complete, and it will provide us with invaluable information on the needs of corn producers in the state. Knowledge of the locations and scope of corn rootworm issues will enable us to prepare customized extension resources based on specific needs of the corn producers in the state," Szczepaniec said.
To complete the survey,  go to