Cheatgrass

The term ‘cheatgrass’ is often used to describe various annual brome species. Locally, cheatgrass refers to downy brome and Japanese brome collectively, both species found throughout Larimer County below 9,000 feet. Downy brome is the more prominent of the two grasses. Dense stands of dry plant material create a fine-fuel source for frequent summer wildfires in the western United States.

Growth Habit – Cheatgrass species follow a winter annual life cycle – seed germinates following late summer or early fall moisture (some spring emergence can occur as well), becomes dormant in winter, and is the first grass to green-up in the spring. Cheatgrass typically sets seed in May and dries down by July. Cheatgrass proliferates following summer wildfires that eliminate desirable plants and create openings for cheatgrass emergence with late summer rains. Also, fire removes the thatch layer that can disrupt an herbicide’s effectiveness.

Identification – Cheatgrass plants grow from 6 to 24 inches tall, depending on available soil moisture, fertility and plant competition. At emergence, leaves are brownish-green. Mature plants are red-brown in color and have erect and slender stems. Leaf sheaths and flat, twisting blades are covered with soft hair. Leaves are approximately 1⁄32 inch wide and 2 to 6 inches long. Panicles are 2 to 6 inches long with slender branches that droop to one side. It has numerous, five-to-eight-flowered spikelets with ⅜ to ⅝ inch awns that are slender, straight and purple at maturity. Each awn is attached to the lower lemma of a hairy, buffbrown, ½ inch long and narrow seed. Roots are fibrous, relatively shallow, and grow many hairs which enable the plants to extract soil water very effectively.

Reproduction – At maturity, the abundant and very prickly seed heads become a nuisance to hikers, pets and livestock. Cheatgrass is a prolific seed producer. Seeds become germinable soon after maturation, but typically do not remain viable for more than two or three years.

Mitigation –

  • The most common herbicide for controlling cheatgrass is Imazapic (Plateau/Panoramic).
  • Treatments should be applied in the fall either pre-emergent or early post emergent (prior to the tillering stage of the grass).
  • Glyphosate (Roundup and others) can be applied at low rates in the winter when perennial grasses are dormant for selective control. It is safe to reseed with natural grasses within a week.
  • No insect biocontrol agents are available for control of cheatgrass. Grazing in the early spring when the grass is palatable can suppress seed head production, but can also be injurious to desirable perennial grasses at that time.
  • Hand pulling or tillage (where feasible) is effective if conducted prior to seed set. Mowing is marginally effective, as re-growth will occur and plants will set seed from a reduced height.

Several mitigation techniques can be used in conjunction with each other. For example, spray Imazapic in the fall as a pre-emergent to the seeds left behind after hand-pulling and mowing in the spring.

Resources

Video by Casey Cisneros of the Larimer County Weed District on “Mitigating Cheatgrass” (YouTube)

Cheatgrass Identification and Control – Colorado.gov (pdf)

Field Guide for Managing Cheatgrass in the …  – USDA Forest Service (pdf)

Downey Browme (cheatgrass) fact sheet – Colorado State (pdf)

Do It Yourselfer’s
Backpack sprayers are available at the office as 2-day loaners.  Sheets on calibrating the sprayers and info about the herbicide Imazapic (brand names Plateau or Panoramic) are available there. Purchase the herbicide yourself – it is available online, at home and garden supplies, Poudre Valley Co-Op, and the Larimer County Weed District office at 2649 E Mulberry St in Fort Collins. A quart covers about 8 acres (4 oz/acre) so you might want to split a quart with a few of your friends. Moisture/rain just prior to or after spraying helps the chemical penetrate the soil and increases its effectiveness.

Backpack sprayers are also available online or retailers. The “Solo” brand 2 gallon sprayer was recommended by LCW as lighter and easier to use.

To pay a professional:
The ecology team has pre-screened a licensed herbicide sprayer and negotiated a community discount with him. David Cummings of Back 40 Land Management is prepared to provide cheatgrass mitigation by spraying Plateau combined with a surfactant in our area.  Contact him at back40land@gmail.com or 970-222-4624. He is offering a community discount (see below), so mention that you are from GVM.

Info from David
A community-level effort with cheatgrass control will ensure cheatgrass levels on individual properties are sustained at lower levels. If only one landowner chooses to treat cheatgrass on a property surrounded by neighbors with an abundance of cheatgrass, I would encourage the landowner to get some of their neighbors on board with treatment before hiring an herbicide applicator. Either way, landowners should be prepared for future treatments and monitoring cheatgrass spread from neighboring properties. Sometimes it takes one brave soul to lead the charge against cheatgrass in their community, and neighbors will follow suit once they see it working.

I’d like to have a better idea of the acreage to be treated before I come up to spray. Sometimes I can get away with not doing a site visit beforehand if the property owner is confident in their estimate on area to be treated and can provide a map of where these areas are. If that is not the case, I can make a scouting trip up there in the next couple of weeks. A weed control contract for three years of cheatgrass treatment could be structured with a single herbicide application per year, or with multiple treatments that target cheatgrass at different times of year. We could also include treatment for other noxious weeds in the contract if you’re interested. I will have a better recommendation for you after I learn a little more about the properties up there.

Would there be a discount if more than one property owner is interested?
I’m willing to offer 10% off weed control this year to each individual property owner involved in a general community effort against weed management, or alternately 20% off of weed control the following year as part of a multi-year community approach

Do you use a backpack sprayer or a boom or both?
I am equipped to safely spray herbicides in a variety of settings. Typically, I use an ATV-mounted sprayer that has both a boom and a hand-gun. I’ve found it to be the most versatile. I use it for areas that are too big to justify a backpack, and too small to justify a tractor-mounted boom sprayer. The ATV allows me to efficiently cover a lot of ground. The ATV does leave visible tracks, but they are mostly just compressed vegetation and not torn up soil. I have never encountered increased weed germination on areas where I previously drove the ATV. I do my best to scrape or blow out weed seeds from my equipment between uses to prevent introducing new weeds to an area.

Would you do repeat application in the spring and again next fall? We understand it takes 3 or 4 years to get rid of the grass.
I encourage a multi-year approach to weed management, but sometimes you can get weed populations to acceptable levels after a year. Especially if you’re able to time herbicide applications correctly and spray multiple flushes of growth throughout the year. Most properties that I service have been accumulating a soil weed-seed bank for years, and often times multiple flushes of weeds need to be coaxed out of a site and eradicated before attempting to seed native grasses. I’ve had sites where one well-timed application of Plateau herbicide in the fall/winter results in virtually no cheatgrass cover the following spring. I’ve also had properties where the herbicide application was timed correctly, but uncontrollable environmental factors or excessive soil disturbances triggered cheatgrass seeds that would’ve lain dormant to germinate.

Do you provide hydro seeding (native grasses and wildflowers) once cheat grass is reduced or fully eradicated?
I can usually get to most areas with my 6-foot drill seeder and tractor, but I have been hiring a subcontractor for projects on steep terrain that require hydro-seeding. He used to be a wild-land firefighter, and his specialty is fire mitigation/restoration. He also installs mountain driveways and does earthwork.

If no precipitation is forecast in early Sept, when would you spray?
I will remotely monitor cheatgrass growth across the Front Range using reliable contacts so that my herbicide applications are timed correctly. Application windows are generally wide enough for me to get to everyone and still have good results. I will reach out to you a couple weeks before I think the conditions will be right in your area to spray for cheatgrass.