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THE BLACK FINGERS OF DEATH FOR CHEATGRASS?

GARDEN TIPS – written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA
DECEMBER 26, 2014

Cheatgrass is an exotic annual weedy grass. It is not a problem for most home gardeners, but it is a troublesome and costly problem in the semiarid rangelands of the West.

Cheatgrass, also known as downy brome, is considered an “exotic” weed because it is not native to the US, arriving from Eurasia sometime in the 19th century. About that same time, the use of western rangeland for cattle grazing started. This allowed cheatgrass to take over rangeland by outpacing native perennial bunch grasses that were not able to recover quickly from the effects of heavy grazing.

Cheatgrass is considered aggressive because it produces copious seeds every year. It is now found on 100 million acres of rangeland and has taken over 41 million acres of land where native plants once dominated. If you look to our surrounding area hills in the spring, the grassy green you see is mostly cheatgrass.

So what is so bad about cheatgrass? First, it has contributed to the loss of millions of acres of native plants, like sagebrush, grasses, and forbs, that support native wildlife. Second, dry cheatgrass is very flammable and fuels wildfires. As a result, wildfires in the semiarid areas of the West are much more frequent than when native plants dominated the landscape. This makes it more difficult for native plants to reestablish.

Third, cheatgrass-fueled wildfires lead to more soil erosion and increased carbon dioxide emissions. Fourth, the production of cattle on rangeland is hampered because the cheatgrass is not palatable for cattle after it dries up. Fifth, gardeners trying to establish landscapes with native plants are also plagued by this seedy, weedy grass.

Before we talk about efforts to curb cheatgrass, we should talk about its life cycle. Cheatgrass germinates in fall or late winter followed by a period of rapid growth in early spring. By late spring it “flowers,” sets seed, and dies. The seeds drop to the soil during the summer and wait for fall and winter moisture to germinate. Of course not all the seed germinates, leaving some viable for the next several seasons and insuring their persistence.

Range managers have tried fire, tillage, and herbicides to control cheatgrass. However, because of the massive acreage and the type of lands involved, control of cheatgrass has been difficult, expensive, and not very effective. Finally, some researchers are making some progress in the fight against cheatgrass. Hooray!

Researchers, supported by the Joint Fire Science Program, are investigating a naturally occurring fungus that might hold the key to getting cheatgrass under control. The fungus, Pyrenophora semenifperda, kills germinating seeds in the lab and in nature. The fungus, nicknamed “Black Fingers of Death” (BFOD) for its appearance in infected seed, secretes toxins that allow it to invade, feed on, and destroy cheatgrass seed.

The scientists have also found that many of the native grasses are resistant or somewhat resistant to BFOD. The team is now working to breed a more virulent strain of the pathogen. They then hope to develop it for use as a commercial biocontrol product. However, if they are able to develop a commercial BFOD product, it will not be a silver bullet. Cheatgrass control will require an integrated approach using other tools and good management practices to reclaim the many acres it currently dominates. For more about the research team and their work, go to http://www.cheatgrassbiocontrol.org/ or http://www.firescience.gov/Digest/FSdigest13.pdf

Published: 12/26/2014 12:41 PM

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