Callaway County
Callaway County
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Jarman's Weekly Agronomy News February 16, 2000 |
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Bt Hybrid Corn Refuge Requirements |
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On January 14, 2000, EPA issued its requirements for "refuge structures" associated with Bt hybrid corn registered for this years' growing season. In other words, the Bt hybrid corn registrants (seed companies) must require growers to plant a minimum of at least 20% to not-Bt. corn. From the beginning, measures to avoid building insects resistance has been a part of registering Bt hybrid corn seed. This year the estimated acres planted to Bt hybrids were high enough to activate this registration enforcement. The major registrants involved are Dekalb, Monsanto, Mycogen, and Novartis. Luckily, we live in the Corn Belt. Corn growers in cotton growing regions must plant a 50% refuge unless Bt. cotton is grown in that area. No Bt. corn hybrids can be grown in the same area as Bt. cotton varieties. This is because of the more serious and typical insect infestations that are a constant part of raising cotton. Then there are 63 counties in Texas, Colorado, Oklahoma, and Kansas were no Bt. hybrids corn can be sold. Concerns with insect resistance in the southwestern corn borer are high. European corn borers have many alternate wild plants they feed upon compared with the southwestern corn borer. With more wild hosts, there is less chance of European corn borers building resistance to Bt. Still, corn is the primary plant European corn borers feed upon. "Structured refuges" are defined as external blocks or plantings on the edge or headlands of fields or strips of rows planted across the entire width of a field. The strips are to be a minimum of six rows wide. The external refuge areas, "blocks", must be planted within 1/2 mile of the Bt. field. If the external refuge may be treated, it is preferable that it be planted within 1/4 mile of the Bt. field. No information on how this is to be administered by the registrant seed companies is available at this time. Some of the language is vague or can be interpreted several ways. More information will be coming as the planting season approaches. The seed companies will be monitoring target and non-target insects during the growing season. These insects include the European corn borer, southwestern corn borer, corn earworm (cotton bollworm), and Monarch butterfly.
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