Cheatgrass, a volatile Eurasian invader, is helping to spread wildfires on Washington state rangelands and across the West.

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The spread of wildfires raging across the region is being aided by the proliferation of cheatgrass, a Eurasian invader that has infested many hillsides east of the Cascades.

Cheatgrass turns brown and flammable earlier in the summer than native bunch grasses and can send flames ripping across a landscape to threaten communities.

Wildfire coverage

Wildfire growth
Twisp fire

“We call it ‘grassoline’ because it burns so hot and fast,” said Ken Frederick, a former firefighter based in Wenatchee who now works for the Bureau of Land Management in Idaho.


• is an annual.

• reproduces by seed.

• ranges from 3 to 30 inches high.

• has a crooked seed head.

• has dark green leaves with a hint of purple.

• spreads its seed by clinging to clothing or animals.

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During the past century, researchers say, cheatgrass has wrought significant changes in rangeland ecology, increasing the extent and frequency of fires in many areas of the West.

This hellacious Pacific Northwest fire season, primed by a poor winter snow pack and summer drought, will only strengthen the presence of the region. As the fires burn, conditions are ripe for the spread of cheatgrass that can sprout during fall rains.

“Most of the areas that have had fires go through, the cheatgrass has cleared out the natives and come back as the dominant species,” said Liam Doran, whose family’s ranch of more than 680 acres north of Twisp last week was threatened by fire surging through cheatgrass slopes.

“You can’t keep up with the speed. You can’t flank it. It’s moving so fast.”

Frederick says that his two closest calls in 13 years of wildland firefighting both involved this grass.

The grasses also can help carry the fire to other locations, such as thick forests of pine and Douglas fir present in some areas of the Okanogan.

For Don Waller, chief of Okanogan County Fire District #6, contending with cheatgrass is just part of the job.

“It’s pretty much an understory of our sagebrush areas … and in real time we don’t even identify it,” Waller said.

Cheatgrass is an annual, offering some green forage for livestock in the spring but often going to seed and turning brown by May. The seeds are attached to spiky awns, detaching like burrs that can be carried off by humans and animals to spread the plant.

Cheatgrass has its origins in southwest Asia, and probably first arrived in the United States via contaminated grains. By the mid-20th century, the grasses had expanded across tens of millions of acres of the West.

The traditional native bunchgrass in the West also will burn. But because those plants hold their greenery longer in the summer, and grow in clumps with spaces in between, researchers say they don’t spread flames as easily and catch fire less often.

As bunchgrass ceded ground to cheat grass, the fires cycles have become more compressed.

“Cheatgrass has … increased the extent and frequency of rangeland wildfires in the Great Basin and Upper Columbia River Basin with significant impacts to natural and fiscal resources,” wrote Mike Pellant, then a rangeland ecologist, in a 1996 report called “Cheatgrass — The Invader that Won the West.”


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Pellant wrote that conversion of rangeland to cheatgrass also can help dry out and warm the top soil layer because it has a shallow root system that depletes the water from that zone, while native grasses send roots deeper into the soil to draw up moisture.

A 2013 study published in Global Change Biology found that cheatgrass in the Great Basin burned nearly four times more frequently than other vegetation types in the 1990s, and also was “disproportionately represented in large fires.”

There are ways to control cheatgrass, but they typically involve herbicides, which can be expensive and must be followed by replanting native grasses.

But that’s a difficult task to launch on a wide scale, particularly on public lands where spraying may be controversial and restoration budgets have been reduced to help pay for firefighting.