MN Fruit & Vegetable IPM News - Vol. 2, No. 3

On April 4, 2005, the EPA approved registration of Syngenta Crop Protection's Callisto (mesotrione) herbicide for use in sweet corn. Callisto can be applied either preemergent or postemergent for broadleaf weed control. Callisto can reduce our reliance on atrazine for broadleaf weed control especially in areas sensitive to water pollution or containing atrazine-resistant weeds. Similar to atrazine, a preemergent herbicide such as Dual Magnum, Frontier, or Outlook, needs to be applied for grass control.

Postemergent applications of Callisto at 3 fluid ounces/acre will control up to 5-inch tall, amaranth, cocklebur, galinsoga, horsenettle, jimsonweed, lambsquarter, nightshade, pigweed, giant ragweed, smartweed, and waterhemp. Based on our research trials, I recommend that Callisto be applied with atrazine and a non-ionic surfactant.

Postemergence control of dandelion, morningglory, prickly sida, pokeweed, and common ragweed can be improved by applying Callisto with atrazine (at 0.25 lb a.i./ acre). Interestingly, the Callisto + atrazine combination also controls Canada thistle. Adding UAN or AMS to postemergence applications of Callisto is not recommended because the nitrogen-based adjuvant increases the potential for sweet corn injury.

Preemergent applications of Callisto at 5 to 6 fluid ounces/ acre with atrazine as a tank mix will control many of the same weeds as the postemergence application. But this control requires a higher rate of Callisto.

Callisto can injure a few sweet corn cultivars. The injury is more severe when the sweet corn is stressed, an incorrect adjuvant, or higher than labeled rate of Callisto is used. Callisto injury appears as bleaching of the whorl. Sweet corn normally recovers from the injury without a yield reduction. Dr. Jerald "Snook" Pataky at the University of Illinois has lead a research team that has identified some susceptible sweet corn hybrids. His results can be found at: http://sweetcorn.uiuc.edu/report-index.html .

Sweet corn also can be injured if a soil applied insecticide is used. Applying an organophosphate or carbamate insecticide within 7 days before or after a Callisto application can result in sweet corn injury. Weeds must be actively growing when applying Callisto postemergent. We recommend that you conduct a small trial with Callisto before treating extensive sweet corn acreage.

Editors note: Not all sweet corn hybrids have been tested for potential sensitivity (phytotoxicity) to Callisto; thus, always a good idea to evaluate under your conditions, with your specific hybrids. For more information, contact: Matthew DeCeault and John Masiunas (masiunas@uiuc.edu)

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ACKNOWLEDGEMENTS

Co-Editors: Bill Hutchison ( hutch002@umn.edu), Department of Entomology, University of Minnesota, Jeanne Ciborowski, Minnesota Department of Agriculture, Ag. Resources Management and Development Division, and Suzanne Wold-Burkness ( woldx018@umn.edu), Department of Entomology, University of Minnesota

The Newsletter is published weekly from May through August, cooperatively, by the Minnesota Department of Agriculture (MDA) and the University of Minnesota (U of MN). Reports are posted on the U of MN and MDA web sites on Fridays. If you have suggestions and/or comments, please send your contributions by 4 p.m., Wednesday to Jeanne Ciborowski, 651-297-3217, jeanne.ciborowski@state.mn.us , MDA, 90 W. Plato Blvd., St. Paul, MN 55107-2094. You can access the Newsletter at the U of MN web site in htm format at: www.vegedge.umn.edu/MNFruit&VegNews/mnindex.htm and at the MDA web site in pdf format at: www.mda.state.mn.us/biocon/fruitreports/

Partial funding for this publication is provided through partnership agreements with the Minnesota Fruit and Vegetable Growers Association (MFVGA) and the United States Department of Agriculture – Risk Management Agency (RMA). These institutions are equal opportunity providers.

DISCLAIMER

Reference to products in this publication is not intended to be an endorsement to the exclusion of others which may have similar uses. Any person using products listed in this publication assumes full responsibility for their use in accordance with current manufacturer directions.

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