A single giant ragweed plant can reduce the yield in an area holding 30 soybean plants by as much as half. That is one of the reasons that farmers are worried by a new generation of superweeds that has developed resistance to the herbicide glyphosate, the active ingredient in Monsanto’s Roundup.

In the past decade, weed resistance to Roundup has extended from a few scattered occurrences to an estimated 11 million acres. This spread was highlighted last summer at a congressional hearing that also explored the issue of genetically engineering crops to withstand application of the herbicide. Journalist Jerry Adler profiled the issue of emerging resistance of weeds to Roundup (glyphosate) in Scientific American’s May issue. Here is a listing of further information to complement the article:

Gene amplification confers glyphosate resistance in Amaranthus palmeri, a study by Philip Westra, et. Al., Proceedings of the National Academy of Sciences, Jan. 19, 2010, Vol. 107, No. 3., pps. 1029-1034

Glyphosate resistance threatens Roundup hegemony, a study by Emily Waltz, Nature Biotechnology, June 2010, Vol. 28, No. 6, pps. 537-538

WeedScience.com, from the International Survey of Herbicide Resistant Weeds

Herbicide Resistant Weeds Summary Table, assembled by Weed Science