No. 19 Article 1/August 4, 2006

First Round of Corn Rootworm Research Evaluations Completed

By the end of the week of July 24, the Illinois Insect Management Program team had completed our first round of corn rootworm research evaluations at four locations--the Crop Sciences Research and Education Center (Urbana), the Northern Illinois Agronomy Research Center (DeKalb), the Northwestern Illinois Agricultural Research and Demonstration Center (Monmouth), and the Orr Agricultural Research and Demonstration Center (Perry). We observed significant rootworm larval damage in our untreated check plots at all locations except Perry. We added the Perry location for the first time in 2006, primarily to test the waters in western Illinois, and we may have to make some adjustments to the location of our trap crop.

The damage in untreated check plots at DeKalb, Monmouth, and Urbana in most experiments was severe (node injury rating of 2.0 or greater on the 0-to-3 node-injury scale), and we observed differences in rootworm larval damage among treatments, which included granular and liquid soil insecticides, seed-applied insecticides, and transgenic Bt hybrids (Herculex RW and YieldGard Rootworm). In fairness to our cooperators in industry, we won't share the data until after they have had a chance to see them. So look for the preliminary results in a forthcoming August issue of the Bulletin.

As we have done during the past couple of years, we will dig and evaluate roots for rootworm larval damage a second time, beginning the week of August 7. We will dig roots from selected treatments (i.e., a soil insecticide, a seed-applied insecticide, and transgenic Bt hybrids) and determine whether the amount of rootworm injury increased from the first to the second evaluation times. We also will dig another complete set of roots from our transgenic Bt hybrid evaluation studies at Urbana and Monmouth. In these trials, we planted an array of transgenic Bt hybrids, with at least one non-Bt hybrid, to determine the amount of rootworm larval injury in both July and August.

The results from all of our corn rootworm control studies should provide additional information about consistency of performance of all of the rootworm control products on the market today. We welcome your observations as well to help us paint a broad picture of rootworm control successes and disappointments in 2006.--Kevin Steffey, Mike Gray, Ron Estes, and Jared Schroeder

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