We've been following the rise of so-called Roundup-resistant weeds as farmers use more and more herbicide-tolerant crops, and now one Iowa State University researcher is warning local farmers they need to change their usage levels before it's too late. "I tell them to quit doing what they're doing now, because it won't work for long," ISU agronomy professor Michael Owen, who has overseen a 10-plot study of weed herbicide resistance on Iowa farms for the last year, told Dan Piller of the Des Moines Register. "Iowa is probably about two years away from a serious problem with glyphosate resistance, and it's better to react now than to wait until it's too late."
"Weed resistance has yet to inhibit Iowa's corn and soybean yields, which have risen steadily in recent years to the 2009 harvest averages in Iowa of more than 180 bushels per acre for corn and 60 bushels per acre for soybeans," Piller writes. Accounts of Roundup-resistant weeds have popped up across the South, and Owen said those examples could be a glimpse of the future for Iowa. "We can't say for sure how deep the damage would be from weed resistance, but it would happen," he told Piller. "What's happened in the South is a good example of what shouldn't happen here."
Owen warned varying herbicides is important to residual weed control. "Farmers [in the South] didn't change their practices," Owen said. "Roundup works so well, they just kept applying it year after year. You need to mix up the herbicides, put different types on the fields." Owen said he isn't an opponent of no-till farming, which is more popular among heavy herbicide users, but he said no-till farmers should be especially vigilant regarding herbicide resistance. "Roundup isn't going away," Owen said. "It will be around for a long time. So have other herbicides like 2, 4-D, Atrazine and DiCamba. They're still around and still can be used." (Read more)
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