No. 2 Article 10/April 6, 2007

Glyphosate, Weeds, and Crops--Who Needs Anything Else?

To fill the need for information on hard-to-control weeds and to address issues arising from extensive use of glyphosate, Extension weed specialists throughout the Midwest have joined forces to develop a series of publications and a Web site titled "Glyphosate, Weeds, and Crops".

The widespread adoption of Roundup Ready soybean and corn has led growers to become heavilyor solelyreliant on glyphosate for weed control. Since the introduction of Roundup Ready soybean in 1996, seven species of weeds have developed resistance to glyphosate. Five of these can be found in the Midwest: common ragweed, giant ragweed, waterhemp, Palmer amaranth, and horseweed (marestail). Along with resistance issues, there are weed shifts associated with the use of glyphosate. Weeds such as wild buckwheat and morningglory, which are not effectively controlled with glyphosate, have become quite common in some areas. Publications in the "Glyphosate, Weeds, and Crops" series tackle the biology of these weeds, explain what has led them to become prevalent in our current cropping systems, and offer suggestions for their management.

Even with the development of glyphosate-resistant weeds, we understand there will be continued use of glyphosate for weed control. To support sensible usage decisions, we have developed several publications: Facts about Glyphosate Resistant Weeds, Understanding Glyphosate, Understanding Glyphosate to Increase Performance, Using Glyphosate Wisely, and Economic Implications of Glyphosate Stewardship.

The Web site provides up-to-date information on glyphosate resistance and implications on weed management as well as useful tools such as a glyphosate rate calculator, yield loss calculator, and tank mix calculator. The publications are also available on the site.

The publications in this series are free. If you would like a copy of any, please contact Kris Ritter ( or me ( or call 217-333-4424.

Currently available:

Coming soon:

--Dawn Nordby

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