SALT LAKE CITY — An aerial assault first launched more than a year ago in City Creek Canyon is proving successful in the war against the state's largest infestation of a rapidly producing noxious weed.
Toxic to wildlife and livestock and armed with sharp barbs, the yellow starthistle is among the non-native plants that have top eradication priority in Utah because of the landscape devastation it can cause.
After an application of pesticide in June 2010, weed warriors took to the sky again this month to conduct an aerial survey and lay down native grass seed that will take root in place of the noxious plant.
Watershed, land and wildlife managers hope the grass will have a chance to grow now, based on what they've seen.
"I would say it's been almost completely successful," said Maria Calvi, Salt Lake City's watershed manager, describing the 65-acre attack zone and how many of the noxious invaders remain. "We have a few outlying populations on the periphery, but that's it. It's about a 90 percent kill."
Yellow starthistle is the enemy that keeps coming, finding its strength in numbers because one plant in a wet cycle is believed to throw out as many as 2,700 seeds in a square foot area.
Mark Farmer, the central region's habitat manager for the Division of Wildlife Resources, said such proliferation allows it to quickly overtake native, useful vegetation and kill it because it is also a water hog.
The result, Farmer added, is a landscape stripped of its usefulness.
"It's like a biological wildfire that can take over the whole canyon," he said. "It's like a slow-moving fire … and that's pretty important wildlife habitat, especially for big game."
For that reason, Farmer said the fight to rid the canyon of the plant is not over, but steadily progress east.
The City Creek Canyon eradication effort is the focus of a three-year, multi-pronged program initiated with funding from the Utah Watershed Restoration Initiative. Launched in 2005, the initiative has completed more than 700 projects, treating in excess of 600,000 acres in Utah.
Rich Riding, the state's noxious weed manager with the Department of Agriculture, said plants in the class of yellow starthistle merit a "rapid response" by agencies because they have not yet taken over the state.
"They're not everywhere yet, and we're trying to get rid of it everywhere we can find it," Riding said.
State efforts are funded with a legislative appropriation of $200,000 and passed onto county weed control departments. About $1 million a year is spread out throughout Utah's 29 counties in a noxious weed control program.
A multi-year effort is ongoing to create a weed database using GIS technology. Riding said such a tool will help those in the fight identify the most urgent places to do battle.
The public, too, is being urged to join in.
Riding said the state has partnered with the Missouri River Watershed Coalition in an aggressive regional effort to spot and then stamp out noxious weeds. Residents who observe non-native plants can enter that information at www.eddmaps.org/mrwc and that information is forwarded to Riding, who can enlist county agencies to help.
"We can use as many eyes and ears as we can," he said.
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