We’re going to get this article out of the way early on in the season, as it’s the plant family I get the most calls about.
Thistles are the most unpopular noxious weed in Archuleta County and for good reason: They are everywhere.
There are five listed species of thistle on the Colorado Noxious Weed List, a list that was created by the Colorado Noxious Weed Act which mandates that all landowners in Colorado manage noxious weeds on their land.
Noxious weeds are introduced plants which wreak havoc on our ecosystems, agriculture production, economies and, in some cases, public health. Not all thistles that occur in Archuleta County are noxious weeds, as there are about 20 native thistle species in Colorado.
Besides being just unpleasant to be around due to their spikey nature, noxious thistles crowd out native vegetation and reduce forage values in pastureland. Invasive thistle plants are excellent at forming a monoculture and reducing the biodiversity that our ecosystems need to thrive.
The five noxious species of thistle are: musk, bull, scotch, plumeless and Canada. All but plumeless occur in Archuleta County.
Musk, bull, and scotch thistle are biennials that live for two seasons before producing seed and dying. These plants should be controlled prior to seed production by either manual or mechanical removal or herbicides.
Canada thistle is a perennial with a creeping root system, like an aspen grove, and pulling, digging or mowing are not particularly effective, though they can keep a population in check if done diligently. Herbicide is the best option for controlling Canada thistle, and a fall application after seed production is most effective.
Before choosing which control method you prefer or would be most effective, proper identification is important. If the plant in question is one of our native thistles, no action is needed. When you determine that it is a noxious thistle, it’s important to figure out whether its Canada thistle or one of the biennials.
At any given site, you may have several of the thistle species present. Canada and musk thistle are the most prevalent in Archuleta County, and there is considerable overlap in their populations. Canada thistle may be treated in the early summer with fair efficacy and musk thistle rosettes can be treated in the fall, or both species could be treated twice a year per the herbicide label guidelines.
Herbicide treatments on thistles can also be paired with mowing or mechanical removal. Using more than one type of control is known as integrated management and will often yield better results than solely relying on one method of control.
When managing thistle, it is important to recognize the native species, as they provide ecosystem services without outcompeting the surrounding vegetation. Native thistles have white, yellow or brown blooms and are less spikey and often a glaucous (blue/green/gray) color. When in doubt, send a photo of your thistle to the Weed and Pest Department for an ID.
Archuleta County Weed and Pest is your local resource for managing noxious weed populations and controlling other pests.
Seed potatoes, seed onions for sale
Seed potatoes and seed onions are for sale. Place your order today for Colorado certified and non-GMO seed potatoes. Five varieties of potatoes are available.
Order by April 30 and pick up your potatoes May 12, 13 and 14 at the CSU Extension Office. Visit archuleta.extension.colostate.edu or call (970) 264-5931to learn more and place your order today.
Learn to can jam
Join us to learn to can raspberry jam on April 16 at 5:30 p.m. at the CSU Extension office. The cost is $25 per person/couple for one jar of jam. Learn all the latest food safety preservation practices. Call (970) 264-5931 to register today.
CPR and first aid classes
CPR and first aid certification classes are offered every other month at the CSU Extension building, generally on the third Monday and Wednesday from 6 to 10 p.m. The cost for the classes is $80 for combined CPR/first aid and $55 for CPR, first aid or recertification. Call the Extension office at (970) 264-5931 to register.
Check out the online option on our website, archuleta.extension.colostate.edu.
Join the fair board
Join the Archuleta County Fair Board and make history. Be a part of preserving the rich heritage and timeless tradition of the Archuleta County Fair and help plan the 75th anniversary Fair in 2026.
You’ll contribute to an annual tradition that brings our community together, supports local agriculture and creates lasting memories for generations to come. To learn more, contact Tonya Steadmon at tsteadmon@archuletacounty.gov or (970) 264-5931.
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