Growing Resistant Worries

While there's been considerable talk among no-tillers about weed resistance to glyphosate products, Bryan Young says early signs point to the development of serious problems.

Even though glyphosate is still an excellent choice for weed control, the weed scientist at Southern Illinois University warns that it’s only a matter of time before resistance becomes a serious issue. In fact, the former National No-Tillage Conference speaker says there is already glyphosate-resistance marestail, and resistance concerns also appear to be developing with waterhemp.

In an area stretching from west-central Illinois to Evansville, Ind., Young says, a strong waterhemp resistance concern may be partly due to the large amount of wheat that is planted in the region. Since many wheat growers in this area double-crop soybeans, they tend to rely more extensively on glyphosate for weed control than growers in other areas. Plus, the area has more than its share of waterhemp worries.

But there are also problems other than glyphosate that are developing with waterhemp resistance. Young says some waterhemp plants are proving to be resistant to herbicides such as Flexstar, Cobra and Blazer that contain protoporphyrinogen oxidase (PPO) inhibitors. He estimates that there are currently more than 60,000 acres in Illinois with PPO-resistant waterhemp.

“If you have PPO-resistant waterhemp in your area, you’re probably located in an area where glyphosate resistance is also showing up,” he says. “The cost of resistance can be great, so you should reduce your risk of getting resistance in your fields.”

Even though he doesn’t think…

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Frank Lessiter

Frank Lessiter has served as editor of No-Till Farmer since the publication was launched in November of 1972. Raised on a six-generation Michigan Centennial Farm, he has spent his entire career in agricultural journalism. Lessiter is a dairy science graduate from Michigan State University.

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