It’s an intrusive weed with thorny stickers, it can grow in dense patches, it uses up water and squeezes out native species, its seeds have stiff bristles and barbs for easy transport, it’s poisonous for horses, and it can be harmful to other livestock with the exception of goats, which love it.

Biologists and historians say the pest called yellow starthistle is originally from Eurasia, crossed the Atlantic with Spaniards in the 1600s, and it likely first came to California from Chile in the early 1850s when the state was in its infancy, as a passenger seed contaminant tagging along with alfalfa seed imports known back then as Chilean clover.

Yellow starthistle took off in Central Valley and Central Sierra rangelands in the 1990s and it was a top concern for ag and cattle industry people for decades. Some farmers and ranchers and other land custodians battled it, some didn’t, and it’s still a problem today in the Mother Lode, say ag commissioners in both Calaveras and Tuolumne counties, and Jim Farrar, director of the University of California Ag’s integrated pest management program.

“It degrades range and grazing pasture lands,” Farrar said Friday in a phone interview. “It’s toxic for horses, it reduces recreational benefits, in areas where there’s hiking or biking it. It’s prickly. People don’t like to hike through it or bike past it.”

Rebecca Miller-Cripps, a UC Cooperative Extension Master Gardener based in Tuolumne County, made a YouTube video about yellow starthistle in 2011. She called it called “one of the worst economic and ecological pests in California today,” in part because it’s fatally poisonous to horses and it’s now established on at least 15 million acres of grazing and open land up and down the Golden State.

Theresa Becchetti, a farm advisor with the UC Cooperative Extension in Modesto, said Friday that yellow starthistle is so widespread in California that is listed as a C-rated noxious weed. That means there’s no state-enforced action that would trigger funds to help control it.

Asked Friday about the invasive plant’s presence in the Stanislaus National Forest, Crispin Holland, a Forest Service botanist, said “Yes we have lots of starthistle” and it “really seemed to get established on the forest following the 1987 Complex Fires. We don’t have a really good comprehensive assessment of how much, but it does cover most of the lower elevations of the south end of the forest.”

Forest Service employees try to limit spread of yellow starthistle by washing vehicles, requiring use of weed-free erosion control materials by contractors, and limited use of herbicides at admin sites and next to roadways, Holland said, but on the larger landscape they are not trying to eradicate, they are simply trying to contain its spread.

“Fires and emergency response still tend to spread weeds, because we don’t have the luxury of taking time to clean weeds when saving lives and property,” Holland said.

Peter Jelito, who lives off Tuolumne Road east of Sonora said he believes this year’s yellow starthistle crop is “phenomenal” and he hopes local property owners and managers will be working on reducing and removing the thorny weeds.

Jelito pointed out a patch of starthistle at the junction of Tuolumne Road and Standard where some of the plants are waist-high and taller. Jelito said he believes it’s too late in the season right now for herbicides to be effective so it’s time to take hoes and backhoes to the weeds.

Kevin Wright, Calaveras County’s ag commissioner, says yellow starthistle is widespread ver the past 30 years and “now it’s pretty much everywhere.” Individual rangeland owners are taking care of the problem as they see fit. The county only sprays roadsides.

“It would be way too expensive for the government to spray yellow starthistle on private properties,” Wright said Friday. It’s up to individuals to take care of it on their own land.”

Gary Stockel, Tuolumne County’s ag commissioner, said the past two winters brought enough rain to trigger boom crops of the pest. Over the past 20 years in Tuolumne County yellow starthistle has slowly moved up into higher elevations.

“Used to be you wouldn’t see it at 3,000 feet,” Stockel said. “Now we see it at elevations up to 5,000 feet, very small populations, in the Stanislaus National Forest and in parts of Yosemite. It’s mainly getting moved by people.”

Tuolumne County recently received a $14,500 Forest Service grant managed by the state Department of Food and Agriculture, effective July 1, 2018 and to be spent by June 30, 2019, to target invasive weeds, including yellow starthistle on non-federal lands, Stockel said.

Specifically the grant is to control invasive weeds that have been moved with equipment used in dealing the tree mortality crisis, in the 3,000-to-6,000 foot elevation range, Stockel said. Caltrans is a partner in the grant, and a portion of the dollars are dedicated to Caltrans weed work along the Highway 108 and Highway 120 corridors.

The funding ends in June 2019 so without additional funding, Stockel said, the county ag department won’t have a program targeting invasive weeds.

Guy B. Kyser, a biologist with a masters in plant ecology at UC Davis, co-authored a 78-page Yellow Starthistle Management Guide back in 2006. Prior to publication of the book, he did a lot of work focused on starthistle over the course of 15 to 20 years.

“It moved into rangeland real fast in the 1990s and it’s spiny so once it gets in there the animals won’t graze it and you can’t use it for recreation,” Kyser said. “It uses up a lot of water the native plants and the grazing plants need to use, the grasses and forage. California state legislators started passing laws and getting grants to deal with it. The foothill ranchers definitely saw it as an emergency.”

Statewide the weed is still a big problem, Kyser said. It’s just one of maybe a dozen real bad invasive species in rangeland area, at elevations from the bottom of the Central Valley and the foothills around the Valley, from 500 feet to 3,000 feet elevations.

Kyser’s recommendations for dealing with yellow starthistle include fire, pre-emergence herbicide chemicals, and mowing.

“The very best thing you can do is have a prescribed fire in year one in the summer,” Kyser said. “And then in year two apply one of those chemicals, Transline or Milestone, in the early spring. The fire stimulates all the seeds to germinate, and the next year the herbicide controls all the seedlings. By year three there’s still going to be a couple escapes that come up. But you’ve reduced the population so much you can just pull those.”

Contact Guy McCarthy at or 588-4585. Follow him on Twitter at @GuyMcCarthy