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Issue No. 3, Article 2/April 22, 2011

One Step Closer to a Seed- Blend Norm Across the Corn Belt

On April 11, Monsanto announced having received approval from the U.S. Environmental Protection Agency (EPA) to begin scaling up for a commercial launch in 2012 of Genuity SmartStax RIB Complete Bt hybrids, which provide a "refuge in the bag" (RIB) for above- and belowground insect pests. Dow AgroSciences also received EPA registration approval to commercialize SmartStax Bt hybrids with the RIB approach with Refuge Advanced branding. Both Bt hybrid product lines resulted from collaboration between Monsanto and Dow AgroSciences. Full commercialization is pending until the necessary state authorizations and notifications are received.

The new federal registrations will profoundly affect the management of insect pests across the Corn Belt. Producers who elect to purchase these Bt hybrids will plant a blend of 95% transgenic seed along with a 5% refuge (non-Bt seed). The SmartStax hybrids will provide for broad-spectrum aboveground protection against lepidopteran pests (e.g., European corn borers, western bean cutworm, armyworms, black cutworms) and corn rootworms. Other belowground insects (e.g., wireworms, white grubs, grape colaspis) will not be controlled by the Cry proteins expressed by SmartStax Bt hybrids. Insecticidal seed treatments (neonicotinoids) will be present on the Bt seed (similar to other Bt hybrids), but they are not likely to provide sufficient control of intense infestations of so-called secondary belowground insects. Where large densities of certain insect pests, such as wireworms, are anticipated, producers will still be encouraged to consider applying a soil insecticide at planting.

Producers will undoubtedly like the convenience of the seed-blend refuge approach, because they will not be constrained with establishing structured refuges (currently still required for many Bt hybrids). With refuge compliance remaining an issue, I presume that EPA liked the ensured compliance that seed blends offer. Registrations of additional Bt products that will enable producers to plant seed blends are anticipated. Syngenta announced on April 5 that they have submitted registration materials to EPA that, if approved, would let them commercialize a 5% RIB for Agrisure Viptera 3220. This product provides protection for aboveground lepidoteran insect pests. Pending the required approvals, these Bt products would be branded and sold under the trade name Agrisure E-Z Refuge.

The anticipated extensive use of these Bt seed-blend (95:5) products in 2012 will continue the acceleration toward an insurance pest management paradigm across the Corn Belt. Similar to the decline of the European corn borer population, I will not be surprised to see population suppression effects with other corn insects, such as corn rootworms. We intend to investigate this suspected trend over the next several growing seasons.--Mike Gray

Mike Gray

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