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Bio-agents a new angle of attack to fight weeds near Sinks, elsewhere

Feb 14, 2016 - By Daniel Bendtsen, Staff Writer

Aaron Foster, supervisor of Fremont County Weed and Pest, outlined new bio-agents in development that will soon be in use to fight invasive weeds.

These bio-agents, often bacteria and fungi, are alternatives to the typical herbicides which can be costly and harmful to desired plants.

Foster spoke last week at Fremont County Farm and Ranch Days in Riverton.

FCWP already has one bio-agent in use, a bacteria called Pseudomonas fluorescens, that was introduced last year to fight cheatgrass. The bacteria hinders cheatgrass's root development, preventing it from competing with native species for water and nutrients.

Cheatgrass has been devastating to Sinks Canyon State Park, and Foster said it has increased the fire risk to the area.

Four fungi also are in development to fight cheatgrass, each attacking the plant differently.

Twenty-seven other bio-agents are also in development at high-tech facilities Foster calls "bacteria breweries." He expects many will be in use within the next few years, fighting nine weeds native to the county, including perennial pepperweed, whitetop and hoary cress.

Fortunately, Foster said, one of the most effective bio-agents will fight leafy spurge, which has been among the county's most chronic issues, especially around Lander.

The county often shares half the cost with private landowners for application of herbicide.

For leafy spurge and Russian knapweed, it will pay up to 80 percent. With bio-agents, however, it pays the full cost.

For weeds that are not yet well established in the county, FCWP also has a free program designed to fight early invaders. Foster urges landowners to call if they see an un-known plant that seems suspicious.

"We find it first, and we find it fast. We have no tolerance. We kill them all," Foster said.

Bob Finley of FCWP, and Chance Marshall, an agriculture educator for the University of Wyoming Cooperative Extension, also led a day-long training program to certify local residents to use pesticides res-tricted to license-holders.

"Is anyone here because they just want to kill prairie dogs?" Marshall asked group. "A lot of people are."

But no one was on Wednesday. Instead, they were joined by residents who've dealt chronic weed issues on both farms and gardens.

Among the restricted pesticides most in-demand is picloram, commonly sold under the brand name Tordon to fight leafy spurge.

Finley said a liberal use of these restricted chemicals isn't a good first solution for most weed issues.

"If you overapply chemicals, you can really go backward: You'll kill everything, and the bare ground creates a niche for other weeds."

He said landowners need to identify the root causes for an influx of invasive species. Russian knapweed often comes in as a result of overgrazing. Finley advised landowners not to clear land for a hay field unless they know it can be sustained indefinitely. Knapweed seeds can lie dormant for 40 years, filling a void if land becomes barren.

The diversity of weeds requires a variety of approaches.

"Spotted knapweed, you can pull it and get rid of it. But if you pull Russian knapweed, you'll make it worse," Foster said.

Others, like leafy spurge, are more vicious and require equally vicious treatment, like picloram, which can have devastating effects.

Picloram was used in warfare during the Vietnam War. Marshall said he visited one property near Sheridan where half-hazard applicable of picloram a decade prior killed a family's trees and lawn.

"It's safe for you, but bad for the environment," Marshall said. "It'll never leave. It stays in the soil and doesn't break down at all."

Finley and Marshall plan more training for seeking a re-stricted pesticide license. Free sessions are set from 10 a.m. to 4 p.m. March 3 at Dubois Town Hall, April 14 at the Riverton UW Extension Office, April 21 in the Lander Extension Office and April 28 in Ft. Washakie's Frank Wise Business Center.

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