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Wiregrass in Wyoming

University of Wyoming researchers with the Sheridan Research and Extension Center are pictured during a recent rangeland survey near Sheridan where they found wiregrass. The invasive species is similar to cheatgrass and outcompetes native grasses.

It’s been two decades since University of Wyoming researchers saw spears of Ventenata dubia, or wiregrass, rising out of the prairie. Since then, the invasive plant has made a home of about 70 acres near Sheridan, warning that this cheatgrass-like species could pose an issue for farmers and wildlife in the state if left unchecked.

In some areas of the field in Sheridan, wiregrass is so dense it’s overtaken about 50 percent per acre of grassland, according to a recent rangeland survey conducted by the UW Sheridan Research and Extension Center.

Ranchers, firefighters and wildlife watchers know how dangerous invasive plants can be for Wyoming’s delicate ecosystems. Grasses like cheatgrass mature earlier than native plants, stealing moisture from native grasses that grow in the spring.

Wiregrass poses similar risks, only some researchers caution the result of an outbreak could be even worse.

Botanists first documented wiregrass in 1997, said UW plant sciences professor Brian Mealor. The teacher is also the director of the Sheridan center that found the invasive outbreak. It was logged in the Rocky Mountain Herbarium, a database of over half a million plant species. But the Sheridan field where researchers first found that sample has been inaccessible for years.

Considering the rate of growth in that time period, it’s likely the species has successfully established itself, he added.

Wiregrass grows in the winter, while native plants are still dormant. It gobbles up nutrients and water from the soil, leaving less for local plants. Over time it can completely take over. This affects everything from hay farming to mule deer populations.

Local wildlife, and farm animals, depend on native plants and shrubs to fatten up for Wyoming’s long, cold winters. They can even find some nutritional worth in cheatgrass. Wiregrass offers them very little, said Slade Franklin, weed and pest coordinator for the Wyoming Department of Agriculture.

“Cheatgrass comes up in the spring and it’s green, there is grazing potential with it,” he said. “From what I’ve heard, Ventenata doesn’t provide that. We have people from Idaho and Utah that tell us we will take all the cheatgrass in Wyoming over the Ventenata grass.”

Idaho and Utah are two of seven states reporting wiregrass population problems. Some of these areas have shown that wiregrass is successful in areas already taken over by cheatgrass.

Just as the life cycle of the two are similar, they pose similar hazards.

The grasses dry out earlier than local plants, potentially moving up the fire hazard in the area by weeks or months.

Wiregrass looks much like wheat when it’s golden, with pods of seeds at the top of thin, dry stalks. In early summer, while native grasses are still green and ripe, golden fields of cheatgrass and wiregrass are one lightning strike from a serious blaze.

Still, a wiregrass spread in Wyoming is hard to predict, Mealor said.

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“Something will get introduced, and it will just sit there and behave itself for 100 years before it really starts to spread and have impact,” he said.

Cheatgrass has been in the state since around 1907, and until recently its potential for long-term growth in Wyoming was contested.

“As recently as the mid- to late-’90s, there was a pretty high portion of people that are very knowledgeable of this type of thing, that thought cheatgrass would not be a problem in Wyoming because of our climate,” Mealor said.

The wiregrass invasion in Sheridan is on remote fields, with very little traffic, meaning it’s unlikely seeds have been carried along the state’s roads, according to Franklin.

But researchers don’t want to take any risks.

“Our approach now is to cast a little wider of a net around the location we know that exists and see if we can document how far it has spread,” he said.

Partnerships are forming with Weed and Pest, UW, federal land agencies, locals and the Department of Agriculture.

They hope to have a plan for the wiregrass-infested area by the fall, when treatment of the invasive species will be most effective.

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