Glyphosate-resistant Palmer amaranth has been economically devastating to row-crop producers in the southern United States. In 2010, a grower in southwest Michigan reported that he was not able to control "pigweed" in his soybean fields with glyphosate. Upon further investigation the pigweed was identified as Palmer amaranth. Seed was harvested and through greenhouse testing we confirmed that this population had a 20-fold level of resistance to glyphosate. In fact, some of these plants survived a 32X rate of glyphosate. This would be equivalent to 5.5 gallons per acre of Roundup PowerMax. The threat of glyphosate-resistant weeds, especially a devastating weed like Palmer amaranth, has a...
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#weed control