DEVILS LAKE, N.D. - Area farmers generally are well aware of the growing danger from glyphosate-resistant weeds. But they’re not always as quick as they should be to take action, a weed expert says.

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“They know it’s a concern. But sometimes they don’t take the steps they should until it reaches their own farm,” says Kirk Howatt, associate professor of weed science at North Dakota State University.

Plunging grain prices increase the odds they don’t take preemptive action, he says.

Howatt spoke Jan. 7 at the annual Lake Region Extension Roundup in Devils Lake, N.D. About 700 people attended the two-day event, which began Jan. 6. This was the 35th year of the Roundup, which provides information on a wide range of agricultural topics.

Resistance to glyphosate, a widely used herbicide that’s often sold under the brand name Roundup, continues to grow in the Upper Midwest. Waterhemp, kochia and ragweed are among the weeds developing resistance.

Wild oats, a common weed in the Northern Plains that hurts crop yields without chemical application, will develop resistance, too, Howatt says.

“It’s just a matter of time,” he says. “It’s already developed resistance to three modes of action.”

In controlling weeds over the long term, it’s important to keep in mind that herbicides kill in different ways. Mode of action is the overall method in which an herbicide affects a plant. Site of action is the specific process in the plant that herbicide disrupts to interfere with its growth and development.

Eventually, no matter what farmers do, weeds will develop resistance to glyphosate, Howatt says.

“We don’t expect to be able to use glyphosate forever,” he says.

But that time can be pushed back by mixing up the types of action used to control weeds.

As crop prices have slumped and profit margins narrow, farmers are tempted to use the least inexpensive ways of controlling weeds, even if those methods aren’t best for combating herbicide resistance long term, Howatt says.

Farmers should visit with an agronomist or chemical specialist to identify the right approach, he says.