Hunt on for noxious weeds in Summit, Eagle counties |

Hunt on for noxious weeds in Summit, Eagle counties

The "Most Wanted" list of common noxious weeds in Summit County. The Friends of Eagles Nest Wilderness and other groups are making a push to knock out noxious weed infestations this summer.
Courtesy of the Friends of the Eagles Nest Wilderness

When human visitors trek through the woods in the High Country, they might be bringing a few hitchhikers along. Seeds of a few dozen different invasive weed species from across the country or world may be hiding between the treads of a shoe or hiking boot. Once these aliens land in the forests, they may spread out and never leave.

To combat the growing infestation of noxious and invasive weeds in Summit and Eagle counties, the Friends of Eagles Nest Wilderness received a $16,000 grant from the National Forest Foundation’s Ski Conservation Fund to conduct weed mitigation projects in the area.

Dr. Jim Alexander, a board member of the Friends of Eagle’s Nest Wilderness, is leading the local volunteer effort to get rid of these weeds. Alexander said more than 30 identified invasive weed species in the area have serious, damaging effects on the local ecosystem.

“These are all invasive species — they don’t come from Summit County,” Alexander said. “It’s a nationwide problem. These weeds come in and there’s no natural defense against them.”

John Taylor, a member of Summit County’s Forest Health Task Force who oversaw voluntary efforts to control noxious weeds in the area for 12 years, said the weeds’ success at invading forests is similar to how boa constrictors have invaded the Florida Everglades — there are no competitors or predators to keep them in check.

“A lot of them come from Europe or Eurasia, and out here they don’t have their natural enemies,” Taylor said. “They have free reign when they land and take over. They wipe out our native species, and it’s sad. You can see fields of nothing but invasive species.”

Invasive weeds do their damage by getting a foothold and spreading into the local biosphere, taking away food and space from native plants, which eventually disappear and get replaced by the invasive plants.

The replacement happens in insidious ways. To ward off animals, some invasive weeds deploy spines or thorns. Some secrete noxious chemicals that irritate the skin and mouths of animals, while others are inedible or even toxic to animals, even insects. Other plants like the musk thistle and oxeye daisy have adapted to make it incredibly hard to eliminate from the local environment.

The chamomile plant, which humans sometimes use for herbal teas and infusions, has a strong odor that is so unpleasant that animals won’t graze on land near it.

The musk thistle thrives when there’s soil disturbance, as a single bright red thistle head can contain 1,200 tiny seeds that get activated with upheaval or even fire disturbance. The seeds can survive 10 years underground until an event activates them, and they may be the first plants growing after a wildfire, replacing whatever burned away before they arrived.

The musk, Canada and other invasive thistles are easy to spot given their bright red, spiky flower heads. Taylor said that there are no significant native plant species in the mountains that are bright red, and suggested hikers go ahead and target thistles of that color by cutting off the flower head or bulb before it has a chance to grow seeds that scatter.

“If it’s red, it’s dead,” Taylor suggested as a rule.

But highest among the “most wanted” list of weeds in the area is the Myrtle spurge. The Myrtle spurge is an ornamental low-lying perennial plant with small yellowish flowers that secretes a toxic, milky latex substance that can cause severe irritation to skin. Even though it is still relatively rare to find in Summit, the spurge is highly invasive, meaning it is spreading quickly into areas it should not be.

Alexander and the Friends of the Eagles Nest Wilderness, in association with Friends of the Dillon Ranger District and the U.S. Forest Service, will be looking to tackle some of the thousands of invasive weed infestations.

This summer, the groups will license a noxious weed contractor to perform professional treatments at eight infestation sites across the Ptarmigan Peak, the Eagles Nest and Holy Cross wilderness areas.

The groups will be looking to recruit volunteers during and after summer to do weed map surveying. Teams of two will “adopt an infestation” from a list of targeted weed infestations in Summit and Eagle counties, then hike to and measure the size of the infestation for USFS records.

Aside from surveying, the Friends of the Eagles Nest Wilderness in association with the Headwaters Group of the Sierra Club will conduct a weed pull day on Saturday, July 13. The original location of the weed pull was Acorn Creek, but due to unfavorable conditions in that area, another location will be selected this week.

To volunteer for weed map surveying or to get more information about or participate in the weed pull day on July 13, contact Jim Alexander at

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