No. 3 Article 1/April 14, 2006

Remember to Plant Non-Bt Corn Refuges

In reviewing a few other states' weekly newsletters and visiting with some people by telephone, I realized that we have been remiss in not reminding corn growers to plant a refuge of non-Bt corn in or adjacent to fields of Bt corn. The use of Bt corn for insect management has become so commonplace that it's easy to overlook some of the simplest, and most important, recommendations (i.e., planting a non-Bt refuge for insect resistance management, a strategy endorsed and explained thoroughly by the National Corn Growers Association [] and all state corn growers associations). As corn planting begins in earnest with drier and warmer weather, it's important to remember to plant non-Bt refuges to preserve Bt technology for our future.

Planting non-Bt corn refuges is required for all types of Bt corn, whether the Bt corn is intended for control of corn rootworms, European corn borers, or both, and whether the brand is YieldGard or Herculex. The basic rule is 20% non-Bt corn refuge and 80% Bt corn, again regardless of target insect or brand of corn grown. For transgenic Bt corn for rootworm control, the U.S. Environmental Protection Agency (EPA) indicates that the refuge must be placed within or adjacent to the field of Bt corn. For transgenic corn for corn borer control, the U.S. EPA indicates that the refuge must be planted within 1/2 mile of the Bt corn. We strongly encourage corn growers to plant their refuges, regardless of the target insect, in the same fields where Bt corn is planted. Planting non-Bt refuges within fields of Bt corn will more likely ensure a better mixing of the insect populations from non-Bt corn refuges with those that survive in Bt corn.

It is also important to note that one brand of Bt corn cannot be used as a refuge for another brand of Bt corn for the same target insect. In other words, Herculex RW cannot be used as a refuge for YieldGard Rootworm corn, or vice versa. However, Bt corn hybrids only for corn borer control can be used as a refuge for Bt corn for rootworm control, and vice versa, because the Bt proteins expressed in the two different types of corn are targeted for different insects.

Let's do all that we can to keep the Bt corn technology viable for everyone for many years to come. Stewardship of the technology is everyone's responsibility.--Kevin Steffey

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