Overreliance on Roundup May Give Rise to Herbicide-Tolerant Weeds, says Purdue Study

Overreliance on Roundup Ready crops may be weakening glyphosate's ability to control weeds, according to researchers from Purdue University. Bill Johnson, a professor of weed science and lead author of the paper, warned that it would just be a matter of time before there are so many resistant weeds that the use of glyphosate products would become much less effective. "We have weeds that have developed resistance, including giant ragweed, which is one of the weeds that drove the adoption of Roundup," Johnson said. Johnson and colleagues surveyed farmers in Indiana, Illinois, Iowa, Mississippi, Nebraska and North Carolina about their views on the ability of Roundup Ready crops to help control problematic weeds. Their paper appears in the current issue of Weed Technology Journal.

The survey shows that farmers who saw the most benefit from using Roundup rotated between types of crops and those that were Roundup Ready and conventional crop varieties. Crop rotation has been shown to be effective in slowing the development of glyphosate-resistant weeds. Johnson said farmers should treat Roundup and Roundup Ready crops as an investment and work to protect the technology.

The survey was funded by Monsanto, developer of Roundup Ready crops. For the complete article, read http://news.uns.purdue.edu/x/2009a/090414JohnsonSurvey.html The paper published by Weed Technology Journal is available at http://dx.doi.org/10.1614/WT-08-038.1