FARGO, N.D. -- An Australian weed scientist has found resistance to all four major herbicides in a global grassy weed, according to a North Dakota State University specialist.
Richard Zollinger, an NDSU Extension weed specialist in Fargo, says it's significant that Stephen Powles, an Australian who spoke at a weed resistance conference in Fargo in 2011, has found this multiple effect in Eleusine indica, a worldwide weed pest. It is known as "goose grass" in Nebraska, Iowa, Missouri, Texas and Illinois. It might also be present farther north, Zollinger says.
In Malaysia, Powles identified a study population that is resistant to three widely used and important nonselective herbicide classes -- glufosinate (Liberty), glyphosate (Roundup) and paraquat (Gramoxone) -- as well as to the ACCase herbicides, such as Poast and Puma.
"If it can happen to one weed in one location it can certainly happen to a weed in our location, depending on whether we treat it the same here as the folks did in Malaysia," Zollinger says.
Before this, the Liberty chemistry has been unscathed by resistance, but Zollinger says he lives by the motto "Mother Nature always wins. She's going to come back and bite you."
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The population was "persistently selected with and evolved resistance to one herbicide, then selected with the next herbicide and then the next with sequential evolution occurring," Powles says, in his research commentary. "We believe that this population has separate mechanisms and thus gene mutations for each of these four different herbicides."
Zollinger says this is more evidence of the folly of using one herbicide until it "breaks," and then going on to the next herbicide class. "You do that four times until you have resistance to every major class."
Farmers need to be proactive by not only rotating chemistry, but also rotating crops.
"If you go corn, soybeans and wheat, then when you finally get to planting sugar beets, you don't have as much of a problem because you've solved it in the other corps," Zollinger says. "The ideal thing would be to throw in a perennial like alfalfa, so growers aren't going to do that" because the perennials aren't as profitable.
