Expect more corn rootworm damage to 2012 Bt corn?
I believe there are some important points to make about these recommendations: An integration of these tactics is encouraged across multiple growing seasons, not all at once. Using multiple tactics should not imply that a Bt corn rootworm hybrid plus a soil insecticide should be a standard and routine practice in a single growing season. Nor does it mean that using a Bt corn rootworm hybrid in a field sprayed the previous season for western corn rootworm adults (beetle management program) should be standard and routine. A corn rootworm soil insecticide properly applied should provide acceptable root protection in most producers' fields. Similarly, a beetle management program that is professionally conducted should provide satisfactory root protection the following season. What we need to avoid is throwing everything including the kitchen sink at western corn rootworms in a single growing season: a Bt hybrid (also containing an insecticidal seed treatment), a soil insecticide at planting, and a beetle suppression program the previous summer. Not only is this approach expensive, but ultimately it may select for resistance more rapidly and lead to unwanted environmental consequences.
In October, extension entomologists Chris DiFonzo of Michigan State University and Eileen Cullen of the University of Wisconsin published a Bt trait table (Adobe PDF). It provides a good reference to the types of Bt proteins expressed by various hybrids, the insects targeted, the type of herbicide tolerance offered, and the specific refuge that can be used. With the introduction of pyramided hybrids and seed blends into the marketplace, this table should provide a nice tool for growers as the use of Bt hybrids increases-along with refuge compliance confusion. I offer my thanks to these entomologists for sharing this useful resource.