Glyphosate Resistance Issues Build 4/18/02003, Laura Engelson, Regional E-Content Editor, Farm Progress Glyphosate resistance is a real and imminent threat, says Chuck Foresman, technical brand manager for Syngenta Crop Protection. Syngenta recently hosted a roundtable discussion for United States and global researchers on glyphosate-resistance weed management, giving them a chance to weigh in on the issue. Professor Stephen Powles, director of the Western Australia Herbicide Resistance Initiative at the University of Western Australia, says herbicide resistance is "a problem we know well in Australia." He says ryegrass has developed multiple herbicide resistance in Australia. It is still susceptible to glyphosate, he says, but he adds there are no new glyphosates coming down the market. Powles believes eventually there will be much glyphosate resistance in the U.S. It won't spell the end of farming, he says, but it will mean change. Diversity is key, says Powles. Continual use of one tool, such as glyphosate, does not provide enough diversity, he says.Officials at Monsanto, inventors of glyphosate, take a slightly different view of the herbicide resistance issue. They note that while glyphosate has exhibited problems with two or three weeds in the U.S., other products including atrazine and paraquat, also have resistance management issues and yet are used widely. Monsanto recommends that producers manage glyphosate closely to get the best control, which usually means hitting weeds earlier and not splitting rates.Yet, at the Syngenta-sponsored event, the mood was one of early containment, with the idea of getting ahead of glyphosate resistance.Michael D. K. Owen, agronomy professor at Iowa State University, says land grant university researchers are going to have to look for alternatives that will not require growers to incur greater risk and expense. Owen says it's not a matter of if resistance will begin, but when. Mark Van Gessel, assistant professor and extension specialist at the University of Delaware, says a proactive approach of additional management would be cheaper than having to change the whole herbicide program once there is a full-scale problem. The experts are recommending alternative strategies, such as crop rotation and utilization of other herbicides. "It's important to recognize we're not talking about major production changes," says Owen. Changes will make weed management more effective, economical and environmentally sound, he says. Foresman says Syngenta is going to continue to look for new modes of action to manage glyphosate as a resource for growers. He says when Syngenta updates its recommendations, there will be new information along these lines. Powles calls glyphosate a "fantastic technology" and he says there's a temptation to overuse it. Owen says it's "going to be a long time until something better comes along."Bottom line: Expect hearing more about glyphosate resistance and control options from the experts and from dealers. For more information on glyphosate, check out the Iowa State Weed Science page.