Date: May 20, 2003

URBANA -- The new active ingredient, mesotrione, contained in the pesticide product Callisto herbicide could be a replacement for atrazine on sweet corn and popcorn crops according to a research project underway at the University of Illinois. Syngenta, the chemical company that registered the new herbicide, cooperated with U of I researchers to evaluate the product's safety and effectiveness on sweet corn varieties.

"There are not a lot of herbicides available for use on sweet corn," said John Masiunas. "From our tests so far, mesotrione has shown to have good crop safety, and is safe from an environmental and health standpoint." Masiunas is a U of I professor in the College of Agricultural, Consumer and Environmental Sciences.

Callisto is currently being registered for use on certain sweet corn varieties, he said, but most farmers grow about half a dozen varieties such as early, main season, yellow and white. Masiunas' team tested six sweet corn varieties and two popcorn varieties. Some of the varieties that were tested showed a tolerance for the herbicide while others developed a bleaching. "However, the plants recovered from the bleaching a couple of weeks after the injury," Masiunas said.

As a result of their research findings and other studies, Callisto is now registered on popcorn. And more testing will be done at U of I with Callisto this summer to understand how tolerance might vary between growing seasons.

Atrazine is in a family of herbicides called triazines that have caused problems in surface and ground water. The recently completed reevaluation by the Environmental Protection Agency (EPA) has restricted the amount used per acre and required set backs from water sources.

EPA has confirmed that atrazine is not likely to be a human carcinogen and that humans are not at risk through dietary exposure. Still, if mesotrione proves to be as effective as atrazine but have a lower environmental risk, this will be a good replacement herbicide for sweet corn farmers.

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