Manage Metabolic Resistance
When weeds develop metabolic resistance to herbicides, they render those products ineffective.
What if it were possible for weeds to not only resist the herbicides used today, but herbicides that haven’t even been developed yet?
“It’s possible with metabolic resistance, which is a scary form of herbicide resistance,” says Dane Bowers, technical product lead for herbicides at Syngenta.
To understand metabolic resistance, it helps to look first at target-site resistance. Historically, this is the type of resistance that farmers deal with most often. “Every herbicide has a specific target site in a plant,” says Aaron Hager, Ph.D., associate professor of weed science at the University of Illinois. “The herbicide has to bind to that target site and effectively shut it down to kill the weed.”
Resistance can occur when changes in the target site stop the herbicide from effectively binding there. “It’s like when you spill water on cardboard puzzle pieces and warp them,” says Ethan Parker, Ph.D., a research and development scientist at the Syngenta Vero Beach Research Center in Florida. “Those pieces no longer fit.”
“The weed develops a hypersensitive response that shifts into overdrive and allows the weed to metabolize the herbicide and survive,” Hager says.
Scientists don’t yet know how many genes might be involved in metabolic resistance. It could be one or two, or 200, Hager adds.
Whether you’re dealing with metabolic resistance or target-site resistance, the management method remains the same: Use multiple effective herbicide sites of action. Also, incorporate diversified cultural practices, like crop rotation and cover crops, Parker says. “Being a good steward is the key to managing resistance issues.”
“It’s possible with metabolic resistance, which is a scary form of herbicide resistance,” says Dane Bowers, technical product lead for herbicides at Syngenta.
To understand metabolic resistance, it helps to look first at target-site resistance. Historically, this is the type of resistance that farmers deal with most often. “Every herbicide has a specific target site in a plant,” says Aaron Hager, Ph.D., associate professor of weed science at the University of Illinois. “The herbicide has to bind to that target site and effectively shut it down to kill the weed.”
Resistance can occur when changes in the target site stop the herbicide from effectively binding there. “It’s like when you spill water on cardboard puzzle pieces and warp them,” says Ethan Parker, Ph.D., a research and development scientist at the Syngenta Vero Beach Research Center in Florida. “Those pieces no longer fit.”
On the other end of the spectrum, non-target-site resistance, or metabolic resistance, is more complex. In this type of resistance, weeds develop the ability to rapidly metabolize or break down the herbicide before it can cause significant damage. Most of the triazine herbicide resistance in waterhemp in Illinois, for example, is coming from metabolic resistance, Hager says.“[With metabolic resistance], the weed develops a hypersensitive response that shifts into overdrive and allows the weed to metabolize the herbicide and survive.”
“The weed develops a hypersensitive response that shifts into overdrive and allows the weed to metabolize the herbicide and survive,” Hager says.
Scientists don’t yet know how many genes might be involved in metabolic resistance. It could be one or two, or 200, Hager adds.
Whether you’re dealing with metabolic resistance or target-site resistance, the management method remains the same: Use multiple effective herbicide sites of action. Also, incorporate diversified cultural practices, like crop rotation and cover crops, Parker says. “Being a good steward is the key to managing resistance issues.”
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