A strain of naturally occurring soil bacteria tested on national wildlife refuges and other Western lands may soon offer rangeland managers a safe new way to manage cheatgrass, an aggressive plant pest.

Cheatgrass is a Eurasian invasive plant that is now found in the United States, Canada, and Mexico. It covers hundreds of thousands of square miles, including the fragile sagebrush steppe habitat that is the home of the increasingly rare greater sage-grouse. In the Great Basin states of Nevada, Utah, Oregon and California, cheatgrass is spreading at the rate of thousands of acres per day, endangering many more animal species and habitats. Wherever cheatgrass grows, unwanted wildfires burn hotter, more frequently and disrupt fragile ecosystems.

The native bacterium doesn’t have a catchy name; researchers refer to it simply as ACK55. But many hopes are riding on this strain of *Pseudomonas fluorescens.*

“I’m convinced it will work as long as the bacteria are applied in the fall to the soil so they can colonize emerging cheatgrass roots in the spring,” says Michael Gregg, a Land Management Research and Demonstration biologist at the Mid-Columbia River Refuges Complex in Washington state. Like a sports agent, the Fish and Wildlife Service scientist is working to convince others that ACK55 belongs in the big leagues of land management. The message is getting through.

In addition to the U.S. Fish and Wildlife Service, government agencies expressing interest in the natural cheatgrass inhibitor include the National Park Service, Bureau of Indian Affairs, Bureau of Land Management and the U.S. Forest Service.

 

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“A biopesticide is much more cost-effective than an herbicide and less damaging to the environment and human health,” says Hilda Diaz-Soltero, senior invasive species coordinator for the U.S. Department of Agriculture.

She hopes the inter-agency interest will speed further research designed to lead to the product’s approval as a commercial biopesticide.

Early test results have been impressive. In long-term field trials at Hanford Reach National Monument/ Saddle Mountain National Wildlife Refuge in Washington, single applications of ACK55 dramatically reduced cheatgrass in three to five years while not hurting other plants or animals. Another field trial is in progress at Deer Flat National Wildlife Refuge in Idaho. In December 2012, the Fish and Wildlife Service committed $200,000 to scale up ACK55 tests to meet Environmental Protection Agency biopesticide registration requirements.

ACK55 is not the only new cheatgrass management tool being studied. “There is a fungus, colorfully named Black Fingers of Death, that is being tested by other researchers,” says Fred Wetzel, National Wildland Fire and Emergency Response advisor and ACK55’s project leader for the Fish and Wildlife Service. In contrast to other controls, Wetzel likens ACK55 to using laser surgery to target and suppress the plant’s developing root cells. “This cheats the plant out of everything it needs to grow and reproduce,” he says.