Kochia has become one of the most problematic weeds in the U.S. – now resistant to at least four herbicide sites of action. And researchers writing in the journal Weed Technology say sugarbeet growers in particular have cause for concern.

In a two-year field study conducted in multiple Great Plains states, researchers explored herbicide-based options for controlling glyphosate-resistant kochia in five common crop scenarios: winter wheat, corn, soybeans, sugarbeets and fallow fields. For each scenario they selected three combinations of non-glyphosate herbicides expected to provide the best results.

Photo credit: Andrew R. Kniss, University of Wyoming

Researchers found that herbicides currently labeled for use in sugarbeet crops averaged only 32 percent control of kochia across all test locations. By comparison, the alternatives to glyphosate produced 93 to 99 percent control of kochia in corn, fallow fields, soybeans and wheat.

Why the disparity? Scientists say there are simply too few registered alternatives to glyphosate for sugarbeet crops. In addition, sugarbeet plants are short in stature. That makes it tough for them to compete against kochia, which can grow as tall as seven feet.

The bottom line: Sugarbeet growers will find it difficult to manage glyphosate-resistant kochia with herbicides alone. They will need to focus on early intervention and on use of other control alternatives.

Want to know more? The article “Herbicide Options for Integrated Management of Glyphosate-Resistant Kochia (Bassia scoparia) in the Great Plains” is available Open Access in Weed Technology vol. 33 issue 5.

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