Fall is the perfect time for herbicide applications

By Ethan Proud
Special to The SUN
As temperatures drop, it is the perfect time for late-season herbicide applications.
Biennial and annual plants that have already flowered will die at the end of the season and will not grow back from the roots. Simply clip the seed heads off and bag them. The rest of the plant can be composted or mulched to provide nutrients for native plants emerging the next season.
Winter annuals and biennial seedlings will be germinating and scattering the ground around the skeletons of the previous season’s growth. These young plants will be attempting to sequester enough photosynthate to convert to starch to survive the winter. Herbicide applications will be highly effective and be actively transported into the roots. It is also possible to mechanically remove these rosettes with a shovel.
Perennial plants such as Canada thistle, yellow toadflax and hoary cress will also be transporting nutrients into their roots in order to overwinter successfully. All of these plants have slightly different growth habits. For example, Canada thistle will be active much later in the season than yellow toadflax, and hoary cress will experience fall regrowth after being dormant for much of the summer. Herbicide applications will be transported into the roots, killing more of the plant than summertime applications.
Mowing plants in the fall will interrupt the transportation of nutrients vital to the plants survival and may reduce the chance that it emerges the following year. Mechanical removal of perennials must be aggressive and diligent or shoot growth will be stimulated and you will compound the problem.
Green plant tissue is photosynthesizing and will be receptive to herbicide applications. When the majority of the leaves have turned yellow, cease applications, as the herbicide will not be moved throughout the plant. Between the first light freeze (32-25 degrees Fahrenheit) and the first hard freeze (25 degrees and lower) is a great time to apply herbicides on Canada thistle.
Archuleta County Weed and Pest is your local resource for managing noxious weed populations and controlling other pests.
Upcoming events
Sept. 29 — Cottage Food Certification and Food Preservation. Registration is required. The Cottage Foods class is $30 and goes from 9 a.m. to 1:30 p.m. Size is limited to 30. The Food Preservation class is $20 and goes from 2 p.m. to 5 p.m. The class is limited to 20, so call today to sign up, 264-5931.
Oct. 19 — Babysitting Class: Offered free to youth 11-18. Call the office to sign up. This class is limited to 15.
CPR and first aid classes
CPR and first aid certification classes are offered monthly by the Colorado State University Extension office on the second Monday and Wednesday of each month from 6 to 10 pm. Anyone needing to receive or renew certification can register by calling the Extension office at 264-5931.
We will also attempt to schedule classes on additional dates with five or more registrations. Cost for the classes is $80 for combined CPR/first aid and $55 for CPR, first aid or recertification. The type of first aid information provided will vary by the needs of the audience.

This story was posted on September 28, 2018.