Pitkin County bugging noxious weeds | AspenTimes.com

Pitkin County bugging noxious weeds

Janet Urquhart
The Aspen Times
Aspen, CO Colorado
Janet Urquhart The Aspen Times

CARBONDALE – Pitkin County has enlisted a new player in its efforts to control unwanted, noxious weeds.

Thursday, county Land Manager Crystal Yates-White and her crew set free roughly 250 weevils along Highway 133 south of Carbondale in an effort to control yellow toadflax, a problem weed that has taken hold in parts of the Crystal River Valley.

Yellow toadflax produces yellow blossoms that look like snapdragons. It is a non-native ornamental plant that has escaped gardens and can choke out native vegetation, particularly in the riparian areas where it thrives.

The toadflax’s extensive root system crowds out the diverse, native species typical of riparian zones, replacing plants that provide habitat and forage with one that has none of those values, according to Yates-White.

“It’s really becoming a problem up the Crystal,” she said.

The county has an agreement with the Colorado Department of Transportation that allows it to deal with noxious weeds along Highway 133 and Highway 82.

Controlling yellow toadflax usually means repeated, liberal spraying with a herbicide; Yates-White hopes the tiny, black stem-boring weevil will prove effective in controlling the plant.

The adult weevils feed on toadflax leaves and stems, and lay eggs in the stems. Young larvae begin feeding within the stems.

The weevils were approved for use in the United States after research showed the weevils wouldn’t attack other plants, according to Yates-White.

“They’re not allowed to be released until it’s been demonstrated that these bugs would rather die than not eat their host plant,” she said.

The weevils aren’t expected to eradicate yellow toadflax – just help keep it in check.

Though the bugs were released along the highway, near county open space, ideally they’ll spread to concentrations of toadflax elsewhere in the area, said Yates-White, who hopes the weevils are able to survive the winter.

If they do, the county may try them in other areas. Yellow toadflax is also a problem along the Roaring Fork River between Aspen and Old Snowmass, she said.

The weevils released Thursday, at a total cost of $500, aren’t the county’s first experiment with a biological attack on noxious weeds.

Two years ago, a moth caterpillar was set loose on poison hemlock in Snowmass Village and along Woody Creek Road.

“It really seemed to munch down the stuff in Snowmass Village,” Yates-White said. “We could definitely see leaf damage.”

The caterpillars did not appear to survive the winter, though, and none were available for purchase last year. Another release is planned this year.

The county has also been using the leafy spurge flea beetle on leafy spurge in the Woody Creek area for the past eight years or so. In addition, it makes a mite that attacks bindweed available to residents.


Using a grant from the Colorado Department of Agriculture, Pitkin County is offering to share in the cost of controlling certain noxious weeds with landowners in certain areas.

The targeted weeds are: absinth wormwood, black henbane, bull thistle, cypress spurge, Dalmation toadflax, Dame’s rocket, diffuse knapweed, leafy spurge (Crystal River watershed only), meadow knapweed, myrtle spurge, oxeye daisy (Crystal River watershed only), plumeless thistle, Russian knapweed, tamarisk, spotted knapweed, sulfer cinquefoil (Crystal River watershed only) and chicory.

Control methods deemed appropriate in the county’s Weed Management Plan will be used. Go to http://www.aspenptikin.com/weeds for more information.

To apply for funds, schedule an on-site visit with the county’s Land Management office at 920-5214 or e-mail crystal.yates@co.pitkin.co.us. Site visits must be completed before the weed treatment, unless an exception is granted.

Once the treatment is complete, a landowner is eligible for reimbursement. Submit an application for funding before June 1, 2011; the materials are available at the county weeds website.

Available funds are limited to $4,000 per project area. The money will be awarded on a first-come, first-served basis until the funds have been spent.

The reimbursement rate is 50 percent if someone is hired to do the work (but only for eligible weeds) or 75 percent for do-it-yourselfers. There is a $200 cap per landowner.

Contact Crystal Yates-White, county land manager, at 920-5214 or at her e-mail address for more information.

– Janet Urquhart

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