Cheatgrass
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Drawing of cheatgrass

Cheatgrass
Bromus tectorum

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Seedling roots continue to grow throughout the winter!


How did cheatgrass get here?
Cheatgrass was introduced to North America through contaminated grain seed, straw packing material, and soil used as ballast in ships sailing from Eurasia. This first occurred between 1850 and the late 1890’s. During this time, abusive use of rangelands, coupled with drought, left many Great Basin rangelands in poor condition. Cheatgrass was able to occupy areas where the native vegetation had been reduced, beginning its persistent march across the landscape. It can now be found across the landscape from the bottoms of desert valleys to mountain peaks as high as 13,000 feet. The plant communities most affected by cheatgrass invasion are those below 6000 feet in elevation. These include the pinyon/juniper woodland, sagebrush, and salt-desert shrub community types.

What are its characteristics?
As a winter annual, cheatgrass seeds germinate at low fall temperatures. Seedling roots continue to grow throughout the winter, and by spring, are capable of out-competing native species for water and nutrients because most native vegetation is just getting started. Cheatgrass completes its life cycle quickly and can become dry by mid-June. Perennial grasses like bottlebrush squirreltail Close-up of cheatgrass plant and Basin wildrye still contain about 65 percent of their moisture at that time. Cheatgrass is a prolific seed producer, and large seedbanks can develop. It only takes a few plants in a sagebrush/perennial grass community to produce enough seeds to overwhelm native perennials in seedling-level competition.

Why is cheatgrass a problem in the Great Basin?
The keys to cheatgrass spread are its short life cycle and prolific seed production. Because cheatgrass stands dry out by mid-June, fires are more likely to occur earlier in the season. These mid-summer fires are tough on native forbs and grasses. Cheatgrass seeds drop prior to fires and will germinate with fall precipitation. This gives rise to dense, continuous stands that make additional fire ignition and spread more likely. Fire return intervals have gone from between 60-110 years in sagebrush dominated systems to less than 5 years under cheatgrass dominance. With every reoccurring fire, cheatgrass becomes more dominant and expands its range further.

How can we fight this weed? Cheatgrass infestation
Eradication of cheatgrass from large areas is not a reasonable goal. Efforts should focus on reducing cheatgrass dominance and increasing perennial vegetation. Increased livestock grazing in early spring helps lower seed production and reduce fuel for fires, but it is doubtful that this alone will help restore more productive species. It is important to remember to remove grazing pressure as native plants begin to flower. Herbicides easily kill cheatgrass, but are not normally cost effective. Some herbicides damage desirable species as well. For small-scale control, refer to the Weed Management Handbook on the University of Wyoming Extension website.

Reducing the frequency of burns in an area is essential for native plants to produce seed and increase vigor. Because it is difficult to establish native plants under cheatgrass dominance, revegetating with competitive, introduced species like crested wheatgrass and forage kochia may help reduce fire frequency and aide eventual native plant establishment. Also, greenstripping may be used to trim down large expanses of cheatgrass to smaller parcels for fire containment and protection of intact native communities.

Images:
-Drawing: USDA-NRCS PLANTS Database / Hitchcock, A.S. (rev. A. Chase). 1950. Manual of the grasses of the United States. USDA Misc. Publ. No. 200. Washington, DC.
-Plant: Intermountain Herbarium.
-Infestation: Intermountain Herbarium.

Text references:
-USDA, NRCS. 2006. The PLANTS Database (http://plants.usda.gov, 26 September 2006). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
-Pellant M. 1996. Cheatgrass: the invader that won the West. Interior Columbia Basin Ecosystem Management Project. Bureau of Land Management, Idaho State Office, Boise, Idaho.
-Whitson, T. D., et.al. 2000. Weeds of the West., 9th ed. Western Society of Weed Science, Newark, CA.
-Young, J.A. and F.L. Allen. 1997. Cheatgrass and range science: 1930-1950. Journal of Range Management 50:530-535.
-Young, J.A. and W.S. Longland. 1996. Impact of alien plants on Great Basin rangelands. Weed Technology 10:384-391.
-Zouhar, Kris 2003. Bromus tectorum. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: (http://www.fs.fed.us/database/feis/, 26 September 2006).