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Leading Weed Scientists Push for Diversification

Maybe Roundup Ready technologies is not one of the original seven wonders of the world. But worldwide weed resistance authority Stephen Powles calls it a once- in —a- hundred -year discovery, and equates it to the discovery of penicillin in human medicine. That's why he is so passionate about promoting strategies that could delay further development of glyphosate-resistant weeds.

"Every grower will look back and lament the day that glyphosate failed on their farm," says Powles, director of the Western Australia Herbicide Resistance Initiative and professor at the University of Western Australia. "That's just how powerful this technology is today."

Powle's hope is that U.S. farmers will act now and learn from lessons of growers in Australia. One of the first cases of recorded glyphosate resistance anywhere was in ryegrass species in Australia.

"The biological reality is that if we cover half a continent with one chemical, there will be biological consequences," he says. "The big impact will be here in the U.S. because that's where the massive amount of use is today. We see very little that would slow the continued adoption of the technology- it's just too good, and reasons to do it are too compelling."

What Powles and cohorts Rick Roush, Director of Statewide Integrated Pest Management Program at the University of California, and Bill Johnson, weed control specialist at Purdue University, suggest is that farmers acknowledge the risk, and consider alternatives that would still let them use this technology now, but prolong its effectiveness to future generations.

"It's got to be all about diversity in weed control," Powles says. "We need to find more ways to get to and confuse the weed. Mixtures of herbicides can be a good way. Using glyphosate with a full-dose partner with a different mode of action will prolong glyphosate's effectiveness over the years."

But tank mixes alone won't solve the problem, Roush contends. "Tank mixes suppress resistance, but they don't delay it forever," he says. The California specialist is a proponent of strategies where glyphosate is not used every single season, year after year. There must be a year now and then when it isn't in the herbicide regime used that season, he insists.

"I tell my dad that I don't want him to leave me a farm full of weeds when the farm passes to me someday," Johnson says. "Farmers need to look at it as investing in the future if they spend a little more for weed control to use something besides the cheapest option every year. They're taking steps to leave the next generation with an environment where glyphosate will still be an important weapon for weed control."