Overlapping Herbicides Helps Manage Resistant Weeds

12/8/2012 7:00 AM

GREENSBORO, N.C. — Managing herbicide-resistant weeds is a growing concern across the Midwest, and farmers are realizing that incorporating multiple modes of action is no longer an option, it is a necessity.

“Weed resistance is real,” said Gordon Vail, technical product lead for Syngenta. “For farmers, it is no longer a question of if, but when resistant weeds will make their way into their fields.”

With weeds such as waterhemp, lambsquarters and ragweed becoming harder to control with glyphosate and other single-mode-of-action herbicides, farmers are overlapping pre-emergence and post-emergence residual herbicides for maximum control.

“A lot of companies claim their products have multiple modes of action. But if one mode of action is an ALS inhibitor and you have ALS-resistant weeds, that means a two-mode-of-action product essentially only has one mode of action that works against that weed,” Vail said. “These are the types of things we’re trying to teach our customers. When you’re considering a herbicide, it’s important to think, What components in this product are actually controlling the weeds I have at the time I’m spraying them?’ ”

Dave Keffeler, who farms in Remson, Iowa, said he made some tweaks to his weed management program after experiencing trouble controlling waterhemp and lambsquarters with glyphosate alone.

“That’s a big reason why we went to Lexar herbicide followed by Halex GT herbicide plus atrazine,” Keffeler said. “Now, we have a program that gives us four modes of action for 100 percent control.”

Farmers in Illinois are incorporating similar weed management strategies.

“Our biggest weed pressures are lambsquarters, velvetleaf and giant ragweed, but giant ragweed seems to be public enemy No. 1,” said Jeff Becker, who farms in Stephenson County, Ill. “It’s very important to start clean, so our first pass is Lexar, which provides residual control until we come back with Callisto Xtra herbicide. Lexar has three different modes of action and Callisto Xtra has two, which helps manage against weed resistance, plus delivers seasonlong control.”

Source: Syngenta.

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