Changing Bt corn options

Corn seed genetics is an important industry, and is moving ahead at a fast rate. Hybrid options are changing every year, and sometimes the choices can seem overwhelming. Along with the many considerations a growers must make for selecting seed, pest protection is at the top of the list. There has been a huge adoption for PIP's (plant incorporated protectants) in field crops, such as Bt to control above/below ground pests. There are many PIPs developed that target persistent pests like European corn borer and corn rootworms. Corn seed can have one protein or a combination to control several species. Some newly-approved changes in refuge requirements from the EPA have further complicated PIP options for some people.

Chris DiFonzo (Michigan State University) and Eileen Cullen (University of Wisconsin) have created a factsheet on available traits and refuge requirements. I found it very useful and thought to pass it along. Also, the National Corn Growers Association have developed a refuge calculator that can be customized for individual farms.

Lastly, there has been quite a bit of discussion about the sustainability of "refuge in a bag." Mike Gray (University of Illinois) summarizes a recent article that says this type of production is actually moving away from IPM because of the constant exposure of Bt to target pests. Christian Krupke (Purdue University) agrees that widespread adoption of Bt with a decreasing refuge can be risky for long term management.

It is important to understand the options for corn seed selection in the future, which includes knowing your actual pest pressure, overall hybrid performance, and seed costs. Also remember incorporating cultural options (e.g., crop rotation, weed control) can help discourage insects from being successful.