Weed specialists seek surveys on resistance to glyphosate

The potential increase of weeds with glyphosate resistance is an emerging major threat to corn and soybean production in Wisconsin and beyond.

University of Wisconsin Extension Service weed specialist Vince Davis and graduate research assistant Ross Recker have issued a call to landowners, crop consultants and agricultural service providers for updated information to help identify any resistance to glyphosate herbicide products by weed species in the state.

With the survey project that they announced this week, David and Recker want to pinpoint the sites at which any resistant weeds are growing and help implement management practices that would preclude widespread failures in weed control.

To do that, they have devised a two-stage survey that seeks the management history of particular crop production fields. In most cases, they indicate that completing the survey should not take more than five or 10 minutes.

The first level of the on-line survey requires providing information for only one crop production field (per survey form), Davis and Recker explain. A second or third form needs to be completed for any additional fields.

For this project, the second level of participation would involve having weed science specialists from UW-Madison take surveys of the identified fields. They would scout for and collect any weeds that apparently escaped a glyphosate treatment earlier in the growing season.

Participants will receive a detailed report about the findings.

Questions about the voluntary participation can be arranged by contacting Davis at vmdavis@wisc.edu or Recker at rrecker@wisc.edu. The phone number is 608-262-1392.

The survey form is available on the http://www.zoomerang.com/Survey/WEB22FSESTMEKJ web site.

As background for the survey, Davis and Recker point out that the limitations on the use of atrazine in Wisconsin have led to increased use of glyphosate, frequently on both soybean and corn crops that in some cases are the only crops in a rotation.

The goals of the program, David and Recker indicate, are to identify areas of the state where there might be shifts to weed species that are more difficult to control with glyphosate and to establish where glyphosate-resistant weeds first appear.

Starting with lambsquarters in 1979, Wisconsin already has 12 plant biotypes that are resistant to one or more modes of herbicide action.

With resistance to glyphosate at one southern site in the state, giant ragweed was added to that list in 2010.