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UW Team Identifies Invasive Grass of Concern to State

June 24, 2016

The director of the University of Wyoming’s Sheridan Research and Extension Center (ShREC) expressed concern after a rangeland survey found a little-known invasive grass on 70 acres near Sheridan.

Ventenata dubia, also called wiregrass, north African grass or simply ventenata, is a shallow-rooted annual that competes with perennial grasses and forbs, and offers minimal forage value for livestock and wildlife. It is affecting hay production in Washington and Oregon.

“This is one we have been concerned about becoming established in our state,” says Brian Mealor, ShREC director and UW plant sciences professor. The U.S. Department of Agriculture reports ventenata, which is found in seven Western states, is gaining attention because of its rate of spread and difficulty of control.

Ventenata is easily mistaken for cheatgrass or Japanese brome, Mealor says. He and UW master’s degree student Clay Wood discovered populations covering up to 50 percent per acre in some locations.

Ventenata originally was collected near Sheridan in 1997 as a specimen for the Rocky Mountain Herbarium. The herbarium is a collection of 825,000 dried plants and fungi housed at the university.

“We were uncertain whether the population was persisting,” Mealor says. “My suspicion is it is spreading, because we found it in a different drainage from where the original collection was made.”

Mealor calls this “a very important find.” He and Luke Sander of Sheridan County Weed and Pest are working with others on a coordinated response, which may include herbicide treatment. They will follow up with more detailed information soon, he says.

Mealor can be reached at (307) 673-2647 or

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