Wisconsin Ag Connection - Glyphosate-Resistant Horseweed Confirmed in Jefferson Co.

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Glyphosate-Resistant Horseweed Confirmed in Jefferson Co.
Wisconsin Ag Connection - 07/24/2013

A glyphosate-resistant horseweed population in Wisconsin has been identified by University of Wisconsin-Madison/Extension researchers from a sample taken last year in Jefferson County.

According to Vince Davis, UW-Extension cropping systems weed specialist at UW-Madison, Horseweed is a broadleaf species of weed problematic to agricultural fields in Northern America.

"Although the weed usually follows a winter annual life cycle, it has the ability to germinate later in the year, choking out spring and summer crops," Davis said. "Horseweed has tiny seeds that can easily be carried great distances by wind, therefore, the threat of this weed spreading herbicide-resistant biotypes to new locations through naturally occurring seed movement is high."

He noted that the adoption of no-till cropping systems in past decades has allowed horseweed to become a major problem in agricultural fields.

"Farmers use a zero tillage agricultural technique to decrease costs, decrease soil erosion, and improve soil health. However, the weed seeds left from the season before also remains near the surface and creates a higher chance of growing again in the next crop," Davis noted. "Increasing the number of weeds in the crop often means increasing the chances for selecting herbicide-resistant weeds."

The Weed Science Society of America says the best way to stop the spread is to manage it first.

The Wisconsin glyphosate-resistant horseweed population was identified through the Late-Season Weed Escape Survey in Wisconsin Corn and Soybean Fields, which is primarily funded by the Wisconsin Corn Promotion Board. The survey will be conducted again in 2013.

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