Opportunistic cheatgrass a European import

If you live in northern Larimer County you have experienced the aggravating effects of cheatgrass: socks full of prickly seeds; dogs irritated seeds in their ears and paws; and patches of your pasture or hayfield taken over by a grass that dries up very early in the season, and produces no useful forage. Where did this irritating plant come from? And more importantly, is there anything we do about it?

Cheatgrass has been “cheating” landowners for years. It originally arrived from Europe as a contaminant in grain and other seed in the late 1800’s. It was also used a packing material as settlers moved west. It spread easily in the coats of animals, and along railways and roads.

by Ellen Nelson
Larimer County Weed District

Cheatgrass is a winter annual, it germinates and begins growing in the fall, and over-winters as a seedling so that it “cheats” and gets a head start the following spring. This head start coupled with a very rapid growth rate early in the spring allows it to outcompete native vegetation for water and nutrients. Cheatgrass is opportunistic and establishes itself easily on land that has been disturbed.

Cheatgrass produces its seeds and goes dormant very early in the growing season, producing large amounts of very fine fuel that leads to increased fire frequency and size. This fire cycle perpetuates cheatgrass making it difficult to re-establish native vegetation. Once established, it is a very prolific seed producer, producing so many seeds per plant per unit of area, that it can overwhelm native perennials.

Fortunately, there are some actions you can take to combat this invasive weed. There are some herbicides that are effective when used at the proper time of year, and there are some perennial grasses that have been shown to compete well with cheatgrass. The ideal time to treat cheatgrass with herbicide is in the fall, when it germinates and begins to grow.

The Larimer County Weed District recommends the herbicides Plateau or Panoramic applied at 4 to 6 ounces per acre in the fall. It may be advantageous to remove the previous year’s dried up old growth to allow the herbicide to contact the cheatgrass seedlings.

If you are familiar with some of the County’s Open Space areas, you may be able to observe some local success stories. The Weed District treated 160 acres in the area surrounding the Indian Summer Trail at Devil’s Backbone Open Space in October of 2010 with 6 oz per acre of Plateau. Happily the timing of that treatment, and the luxurious amounts of precipitation in May and June resulted in a wonderful resurgence of the native grasses in the areas that were treated.

In total the Weed District treated approximately 500 acres of cheatgrass last fall, including areas at Eagle’s Nest and Red Mountain Open Spaces. If you are familiar with these natural areas, you may want to see if you can see a difference in the vegetation.

Very often, simply eliminating the first fall flush of cheatgrass is sufficient to release the native perennial grasses for an exciting resurgence of native vegetation. Native grasses that are seen to reassert themselves when cheatgrass is removed are Western wheat, blue grama, sideoats grama, needleandthread grass, green needlegrass and many more. Sometimes, it may be helpful to reseed with perennial grasses that have been shown to compete well with cheatgrass. When reseeding with native grasses, consider the species listed above.

There is an ongoing debate in the natural resources community about reseeding with non-native grasses, especially if they can outcompete cheatgrass more effectively than some of the native grasses. Several cultivars of crested wheatgrass have been shown to compete very well with cheatgrass, and even though this is not a native grass, it provides more forage, less fire danger and an opportunity for vastly improved range and pasture than a monoculture of cheatgrass.

For more information on weeds, weed identification, pasture management, reseeding, herbicide recommendations, and free site visits please contact the Larimer County Weed district at 970-498-5768.