USA soil scientist uses bacteria to ward off weeds

Dec 8, 2011

PULLMAN, Wash. -- Ann Kennedy leaned forward over her desk, the better to share her exitement. "We're talking about a bacterium that could change the fabric of the lands of the West," she said. "It could change how the West looks." A soil scientist with the USDA Agricultural Research Service, Kennedy has been testing organisms found in soil that can inhibit the growth of various types of weeds. Kennedy and her fellow researchers examined 10,000 naturally occurring isolates, looking for those that attack weeds like jointed goatgrass, cheatgrass and, potentially, medusahead. They excluded those that hurt crops like wheat and barley. They ended up with a group of about 100 isolates that inhibited the weeds, but not crops or native plants, and singled out the bacteria pseudomonas fluorescens.

A pint per acre of the organism will inhibit cheatgrass, Kennedy said. The idea is to apply it with a herbicide or drill it in. After application on several sites across Washington, Kennedy observed a 20 to 40 reduction in cheatgrass in the first year. In the years following, the organism continues to reduce cheatgrass. At each site, beneficial native plants replaced the cheatgrass, Kennedy said.

Herbicides like Maverick are currently used to control cheatgrass, but are expensive and must be used annually, Kennedy said. "What you're talking about doing is throwing the weed pressure way back to when cheatgrass wasn't even found," she said.

Cheatgrass has a high fire potential and low protein, and can overtake pasture and rangeland. If its competitiveness can be reduced, it could be replaced by more beneficial vegetation.

The bacteria could also help reduce jointed goatgrass, she said.

If it works, Ritzville, Wash., wheat farmer Jerry Snyder said farmers will see a boost in yield and income because they won't have to travel over the field as often or use as many herbicides. Snyder said he would like to see the product go to university experiment stations first, testing it on various soil conditions. If successful there, he said, it could have applications throughout the United States.

"You've got big issues with medusahead all over the West wherever you've got grazing cattle," he said. "Wherever you've got wheat, you've got jointed goatgrass."

Kyle Hartmeier, vice president of strategic management for Northwest Agricultural Products in Pasco, Wash., said his company is applying for Environmental Protection Agency registration and is developing the bacteria commercially. "I think it would add an additional tool to farmers' arsenal of chemistries and tools to combat a very tough group of weeds out there," Hartmeier said.

Hartmeier said the registration process is undefined. He speculated it will take several years, noting it is in the EPA's hands at this stage.

Kennedy continues her field studies. She is excited about the potential for similar discoveries. "Do you know how many organisms are out there in the soil waiting to be found, that do something we want?" she said. "We can find these same kinds of organisms for every single weed we have."

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