No. 2 Article 5/April 9, 2010

Managing Glyphosate-Resistant Weeds in Illinois

The occurrence of glyphosate-resistant weed populations in Illinois has unquestionably increased since the initial discovery of glyphosate-resistant horseweed (aka marestail) several years ago. Populations of glyphosate-resistant waterhemp, the other weed species in Illinois with confirmed resistance to glyphosate, will likely spread across much of the state during the next few years, further complicating postemergence weed control. No novel herbicide active ingredients for postemergence control of broadleaf weeds in soybean are likely to be commercialized in the next few years, so managing herbicide-resistant weed populations will become increasingly challenging into the foreseeable future.

For the past three seasons, the Illinois Soybean Association has provided generous funding to support applied research focused on defining viable options for managing glyphosate-resistant weeds in soybean. Weed scientists from the University of Illinois, Southern Illinois University, and Western Illinois University have collaborated on a variety of (mostly) on-farm field research projects, culminating in the publication Help Stop Glyphosate Resistance (Adobe PDF). This new brochure provides recommendations for managing glyphosate-resistant waterhemp and horseweed in soybean and is available in PDF format to download at We encourage soybean farmers to peruse the information and contact Dr. Roskamp (WIU), Dr. Young (SIU), or me with any questions.--Aaron Hager

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