Noxious weed calendar
The 2022 Weeds of Garfield County calendar is available. Produced by Garfield County Vegetation Management, the free calendar features stunning images of county landscapes, residents, wildlife, and livestock. Each month includes information about various noxious weeds and what is being done to prevent them from spreading.
The calendars are available at all county branch libraries; and the first floor reception office in the Garfield County Administration Building in Glenwood Springs and Rifle. You can also contact Garfield County Vegetation Management at 970-945-1377, ext. 4305 or 4315, or email Garfield County Vegetation Management and we’ll be happy to mail you a copy while supplies last.
Fall Weed Watch: Russian knapweed/Rhaponticum repens
Russian knapweed/Rhaponticum repens
• Perennial forb growing 18-36″ tall
• Stems are erect, thin and stiff and covered with short gray hairs
• Plants reproduce primarily by deep, creeping adventitious roots but may also produce up to 1,200 seeds
• Roots have a distinctive black or dark brown color and scaly appearance
• Solitary, urn-shaped flowers typically pink to purple
• Can be distinguished from other knapweeds by the papery tips of its floral bracts
Russian knapweed grows easily in many different areas, such as roadsides, riparian zones, pastures and croplands. The plants rapidly form dense colonies that outcompete desirable species or forage. Russian knapweed is allelopathic, meaning it can exude chemicals that inhibit growth of desirable plants. It is also poisonous to horses and can cause serious illness or death.
Russian knapweed shoots emerge early in spring to form rosettes and begin to bolt in late May to June. The plants flower from June through August and set seed in late summer to early fall. The rosette stage is the most effective time to control the plants with herbicide, so spraying should occur in early spring before the plants bolt or in fall after the first frost.
Prevention is the best method of knapweed control as the plants rapidly colonize bare or disturbed areas. Maintain healthy land with native, desirable species and continually monitor for knapweed presence. If found, treat immediately and plant competitive species in bare areas. Limit seed dispersal by avoiding driving through or bringing livestock into infested areas.
Mowing several times before the plants bolt may help limit nutrient reserves and stress the plants. A combination of mowing and herbicide application will further enhance control. There are also several biocontrol options available for Russian knapweed control, but this method is most effective when combined with other control options as part of an integrated weed management plan.
Annual follow-up treatments are essential and chemical recommendations will vary depending on the specific site and surrounding land use.
For more information or specific recommendations on Russian knapweed control, please contact Garfield County Vegetation Management:
Steve Anthony: 945-1377 x 4305 or email
Sarah LaRose: 945-1377 x 4315 or email
Garfield County Achieves Biocontrol Milestone
Garfield County is the first county in the state to have its own Russian knapweed biocontrol nursery and distribution program. Since 2000, Garfield County Vegetation Management has worked with the Colorado Department of Agriculture’s Palisade Insectary to release various biocontrol agents on noxious weeds throughout the county. Biological control, or biocontrol, is the use of natural enemies – such as insects or pathogens – to help control weeds or other pest organisms.
Noxious Weed Cost Share program
Garfield County and the Bookcliff, Mount Sopris, and South Side Conservation districts are once again offering landowners financial assistance for controlling noxious weeds and trees on their properties. Cost-sharing is available for all state of Colorado listed noxious weeds and watch list species, including Russian olive, tamarisk, and Siberian elm trees.
Cost share program -|
Noxious Weeds of Colorado: 14th Edition
The latest edition of “Noxious Weeds of Colorado” by Colorado Weed Management Association is available for interested landowners. This pocket-sized field guide includes the A, B and C Colorado State Noxious Weed Lists as well as a Watch List. Species are listed in alphabetical order and each comes with a detailed description as well as pictures to help in identification. Stop by our office to pick up a copy. We are located in Rifle at 195 W. 14th Street, Building D, Suite 310.
Biocontrol in Garfield County
Last year, approximately 3600 biocontrol agents were released for the control of Russian knapweed in Garfield County. More are scheduled to be released in 2019, and the insects seem to feel right at home.
Weed management plan
The Garfield County Weed List provides guidelines for managing designated noxious weeds which represent a threat to the continued economic, environmental and agricultural value of lands in Garfield County. This plan provides for the implementation of the Colorado Noxious Weed Act by detailing integrated management options for designated noxious weeds.
Weed management plan
West Nile precautions
Mosquitoes are appearing in unusually high numbers in Garfield County, prompting the risk of West Nile virus infections. Take precautions, West Nile mosquitoes appeared in five Colorado counties, including Mesa County last year.
Steve Anthony, Garfield County Vegetation Manager, 970-945-1377, ext. 4305
Sarah LaRose, Program Coordinator, 970-945-1377 ext. 4315