Herbicide rotation sparks performance
By John Pocock
Josh Smith, Auburn, Illinois, planted some LibertyLink soybeans for the second consecutive year in 2010. It was also the first year he planted all his soybean acres to LibertyLink.
“LibertyLink soybeans yield well, and the Ignite herbicide does a good job on the broadleaves that have been hard for us to control the last couple years,” says Smith, who raises corn and soybeans on about 1,000 acres. “We have some waterhemp that’s been pretty tough to kill with Roundup. We also have some buttonweeds, or velvetleaf, that seem like they might be developing some herbicide resistance too.”
Herbicide resistance is a real worry now, especially in soybeans, emphasizes Smith. “In the past, we would normally apply two passes of Roundup,” he says. “Now, we’ve rotated to LibertyLink soybeans and Ignite herbicide, which uses a different mode of action.”
By rotating glyphosate-tolerant crops with LibertyLink crops that are tolerant to Ignite (a glufosinate-containing herbicide), farmers can help to prevent herbicide-resistant weed development, says Andy Hurst, Bayer CropScience, Ignite product manager. “We can’t continue to spray 97% of the soybean acreage in the U.S. with glyphosate without also seeing a rapid expansion of weed resistance,” he says. “Ignite herbicide and LibertyLink traits currently provide the only non-selective herbicide alternative to glyphosate and glyphosate-tolerant technology. So now, farmers truly have a means to rotate their herbicides and hopefully preserve the utility of glyphosate as a weed-control product.”
Ignite controls many troublesome weeds, including weeds that are now showing resistance to Roundup, confirms Jeff Gunsolus, University of Minnesota Extension weed scientist. “Ignite offers fairly broad-spectrum weed control, and it also does well on glyphosate-resistant broadleaves like common and giant ragweed and common waterhemp,” he says. “So, much of the appeal with LibertyLink soybeans is that it will control the more difficult broadleaf weeds with a different chemistry than glyphosate.”
While still popular among farmers, glyphosate is steadily losing effectiveness due to overuse, says Gunsolus.
“Herbicide diversification is the key to preventing resistance,” he says. “Don’t just go to one system and keep using it – that’s what we’ve been doing with the glyphosate system, and now we’re seeing resistant weeds that are causing us headaches.”