Get Wild: Get to know Summit County’s noxious/invasive weeds

John Taylor
Get Wild
Oxeye Daisy and Scentless Chamomile are noxious weeds; Shasta Daisy is not.
Summit County Weed Control Department |

There are 32 species of noxious and invasive weeds found in Summit County, mind you, I said county! These invasive species do not honor boundaries. Granted, they entered our developed areas initially, but with time, migrated to our national forests as well as our wilderness areas. Construction activity, along with human and canine traffic, have brought in and assisted the migration of these unwanted species.

Noxious weeds are out of control, and we need a hardy community effort to control them. Over 15 years ago, Summit County sponsored a volunteer noxious weed pull for seven years running that brought out over 100 volunteers each year. This year, the weed pull is coming back! 

Save the date: 8 a.m. to 2 p.m., Saturday, July 8. This year we will designate chamomile and musk thistle species for “elimination.” Additional information will be forthcoming. As in prior years, this year’s weed pull day will commence with a kickoff at the Summit County Senior and Community Center. 

These unwanted guests have taken over, invaded and overrun native species, eliminating an important food source for wildlife. Both false chamomile and musk thistle can be eliminated without spraying.

False chamomile

An annual (lives only one season) that produces up to 1 million seeds per plant. A high percentage of these seeds may lie around prior to germination for up to 15 years! The plant has ferny or feather-like leaves, and may grow up to 2 feet tall. The yellow center of the flower is the seed head, and once the flower blooms, the seeds are viable. Pull the plant and put seed heads in the garbage. Do not pull and leave on the ground! Note: pull the plant and bag it, with or without the flower.

A single musk thistle can produce 120,000 seeds, according to the Colorado Weed Management Association.
John Taylor/Get Wild

Musk thistle

A Biennial (lives for two years), with the plant’s first year consisting of it being a flat rosette up to 2 inches wide, which can cover native vegetation. It has a single seed head per stem, and numerous stems per plant. On year two the plant bolts, sending up stems with heads containing up to 120,000 seeds per plant. Seeds may lay around prior to germination for as long as 10 years! Mature leaves are up to 10 inches long and deeply lobed, with silvery edges and a light green midrib. Musk plants may grow up to 10 inches high. The purple/red flowers may be up to 2 inches wide. Each seed develops a white pappus (parachute) that allows the seed to float away with the wind and spread. Be sure to pull the heads with gloves and bag because the bracts below the heads are very sharp! Just bag the heads and leave the pulled plant on the ground.

Musk thistle seeds can lay dormant for several years waiting for good conditions. After that, they can quickly germinate into immature plants, called rosettes, pictured here.
John Taylor/Get Wild

One application or outing per season does not end a musk thistle! Musk seeds germinate as rosettes on their own schedule during the entire summer season. Successful volunteer efforts need to scrape off the year one rosettes during outings and cut off and collect maturing heads — ideally a few times per season. Put them in the garbage, cut the plant at the tap root, or pull it out if they are easily removed, and leave. Since those parachute-like seeds move by wind and may go a significant distance, it is important to be thorough! I urge volunteers to return during the season to chop off late rosettes.

So, please, put 8 a.m. on July 8 at the Summit County Senior and Community Center on your calendar! Good information and leadership will be provided.

John Taylor

John Taylor was recognized by the Summit Foundation John Taylor in 2009 for its Outstanding Citizen award in recognition of his volunteer work with the American Red Cross, Wildfire Mitigation and Emergency Planning, Friends of the Eagles Nest Wilderness noxious weed program, State Weed Advisory Board, wilderness protection and Summit Senior Center. He’s a past chair of the Colorado Department of Agriculture Noxious Weed Board and past licensed Department of Agriculture Pesticide Applicator Program member.

Support Local Journalism

Support Local Journalism

As a Summit Daily News reader, you make our work possible.

Summit Daily is embarking on a multiyear project to digitize its archives going back to 1989 and make them available to the public in partnership with the Colorado Historic Newspapers Collection. The full project is expected to cost about $165,000. All donations made in 2023 will go directly toward this project.

Every contribution, no matter the size, will make a difference.