Michigan State University field crops entomologist Chris DiFonzo and University of Wisconsin entomologist Eileen Cullen recently updated and published their “Handy Bt Trait Table.” This great reference provides information for transgenic hybrids on the types of Bt proteins expressed, insects controlled, herbicide tolerance and refuge requirements for selected traits. 

Depending on the specific Cry protein (below ground and/or above ground) expressed and combinations of Cry proteins delivered the large range of Bt hybrids sold, refuge requirements for hybrids vary considerably. This can be confusing and growers are encouraged to make sure they fully understand their chosen products. The different types of refuges can range from 5% and 20% structured refuges to seed blends (5% and 10% {RIB}). 

Growers are encouraged to use Bt hybrids as part of a fully integrated pest management program. The use of non-Bt hybrids remains an option and may be more appropriate in certain areas where less insect pressure is expected (e.g., western corn rootworm injury in southern Illinois). Seed costs have increased in recent years, and with the current and projected market prices of corn, growers will need to manage inputs even more judiciously in 2014.