There isn’t a single day in the summer that goes by without someone asking about thistles.
Thistle has become nearly synonymous with noxious weeds, though, of the roughly 70 listed species, only five are thistles. Musk, Canada, bull, scotch and plumeless thistle are all noxious weeds in Colorado and have been introduced from across the Atlantic. Colorado is also home to about 20 native species of thistle that are beneficial in our local ecosystems.
What makes the exotic thistle species so bad? When plants or animals are introduced to a new ecosystem by artificial means, they leave behind the checks and balances in their native habitat and can outcompete the native plants in their invaded range. Noxious thistles can quickly form a monoculture, which reduces local biodiversity.
In Archuleta County, we have four of the five noxious thistle species, as plumeless thistle has yet to arrive. Of the four, three are biennial (musk, bull and scotch), meaning that they live a two-year life cycle. They form a rosette in their first year, and flower and die in the second.
All these thistles grow from a single taproot, and individuals can be spaded from the ground quite easily. The taproot may go down several feet, but only the first 4 inches or so needs to be removed.
Musk thistle is the most prolific noxious weed in Archuleta County and is commonly called Russian thistle or Canada thistle. Russian thistle is actually not a thistle, but a type of tumbleweed in the goosefoot family, and Canada thistle is a creeping perennial, so a mistaken identity may result in improper management recommendations.
Canada thistle, as mentioned above, is a creeping perennial, meaning that it lives and flowers for multiple years and spreads through its root system, creating a clonal colony. Mechanical control of creeping perennials is a war of attrition as any disturbance to the roots will trigger more growth. Herbicides are a better choice for controlling Canada thistle. When using herbicides, always read the label.
When managing thistles, it’s important to properly identify them first, not only to make sure you are using an appropriate control method, but to ensure that you are not removing native thistle species.
A few generalities that aren’t set in stone to help you differentiate between native and non-native thistles are as follows:
• Native thistles usually have white, brown or yellow flowers.
• Non-native thistles usually have purple flowers.
• Native thistles have a silvery underside of the leaf.
• Non-native thistles are green on the bottom of the leaf.
• Native thistles grow in a solitary manner.
• Non-native thistles grow in thick bunches.
When in doubt, send pictures or bring samples to the Archuleta County Weed and Pest Office.
Archuleta County Weed and Pest is your local resource for managing noxious weed populations and controlling other pests.
Email list
Do you want to be added to our email distribution list to learn about upcoming programs and the latest resources? Email cindi.galabota@colostate.edu to be added to our list.
Or, to learn more about the many programs, resources and services offered by Colorado State University (CSU) Extension, visit https://extension.colostate.edu.
Be Prepared for an
Emergency workshop
A “Be Prepared for an Emergency” workshop with Cindi Galabota, CSU Extension director, and Lacy Capre, Archuleta County Public Health outreach specialist is set for Tuesday, July 15, at 5 p.m. at the CSU Extension building at 344 U.S. 84.
This free workshop will cover the best practices for preparing for and recovery from an emergency.
Fair Promotion Day
4-H members will be seen around town on July 9 from noon to 2 p.m. hanging posters for the 74th Archuleta County Fair.
They will be in small groups, stopping by your businesses in hopes of hanging a flyer in your window, on your community bulletin board or leaving some info cards on your desks.
The Archuleta County Fair is July 31-Aug. 3, and is where 4-H members showcase the projects they have been working on all year.
Feel free to speak with them about the projects, how to purchase tickets to the Chuckwagon Dinner and when to see the shows.
Many 4-H members will be selling their livestock animals in the Junior Livestock Auction on Aug. 2, so be sure to inquire about how you can get involved.
CPR and first aid classes
CPR and first aid certification classes are offered every other month at the CSU Extension office, 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, https://archuleta.extension.colostate.edu/.
