No. 1 Article 7/March 23, 2007

Loading Up for Rootworm Control

Another rumor circulating during the winter months focused on the intention of some corn growers to "load up" this spring for control of rootworms and early-season insect pests. We have heard that some growers are seriously considering applying a soil insecticide to rootworm Bt corn, the seeds of which are treated with an insecticide (i.e., Cruiser, Poncho). We have seen no data to support the rationale for using three active ingredients against corn rootworm larvae, whose populations have a rich history of developing resistance to control tactics, and we are concerned about this sledgehammer approach. We do not recommend the use of a soil insecticide, even at a reduced application rate, to further protect rootworm Bt corn. After all, aren't the seed-applied insecticides labeled for control of almost any early-season insect pest you might encounter? If growers have
little faith in the efficacy of the seed-applied insecticides, they should ask the manufacturers of these products what they should be able to expect.

In future articles in the Bulletin we will provide more comments about the use of soil insecticides and rootworm Bt corn, and your feedback will be welcome.--Kevin Steffey and Mike Gray

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