Source: California Invasive Plant Council

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Invasive Plants of California's Wildland

Bromus tectorum
Scientific name   Bromus tectorum
Additional name information: L.
Common name cheatgrass, downy brome, downy cheat, downy chess, early chess, drooping brome, cheatgrass brome, wild oats, military grass
Synonymous scientific names none known
Closely related California natives 9
Closely related California non-natives: 13
Listed CalEPPC Red Alert,CDFA nl
By: Jim Young
bromus tect-map

Distinctive features:

Cheatgrass (Bromus tectorum) typically is a short grass. Seedlings are bright green with conspicuously hairy leaves, which suggests the alternate common name, downy brome. At maturity the foliage and seedheads often become reddish. After maturity the fine herbage is characterized by a light tan reflectance. The nodding open panicles with moderately awned seeds (caryopses) are distinctive. Seeds readily penetrate clothing of passersby.

Poaceae. Phenotypically extremely variable annual grass. Can mature at 1 in (2.5 cm) high with single floret or at 24 in (60 cm) with multiple tillers and fertile florets. Leaves: leaf sheaf is densely soft-hairy; blade 1/16-1/8 in (0.1-0.5 mm) wide. Leaf blade can be nearly glabrous to dense soft-haired, but is generally softly cillulate near the base. Inflorescence: open to more or less compact panicle with branches usually nodding. Flower: spikelet subcylindric to slightly compressed; glumes glabrous to short-hairy, lower 0.25-0.5 in (5-8 mm), 1-veined, upper 0.33-0.75 in (7-12 mm), 3-veined. Floret: 3 to 7 per spikelet; lemma body 0.33-0.5 in (9-13 mm) long, 5 to 7 veined, glabrous to short-hairy, tip with 2 teeth, 0.07-0.13 in (1-3 mm) long, awn 0.33-0.75 in (8-18 mm) long. Description adapted from Wilken and Painter (1993) and Hitchcock (1950).
bromus tect-illus


Cheatgrass is widespread throughout California. It is the dominant annual grass on sagebrush (Artemisia sp.) rangelands on the Modoc Plateau in northeastern California and along the eastern Sierra Nevada to Owens Valley. It is relatively rare in the annual range communities of California west of the Sierra Nevada, but widespread throughout the Great Basin, Snake River Plain, and the Columbia Plateau. Cheatgrass is a weed of croplands, especially winter wheat and alfalfa. In wildlands it is most commonly found in sagebrush/bunchgrass communities, although its distribution extends to higher-elevation juniper, pinyon-juniper, and pine woodlands.

Cheatgrass grows in many climatic areas. It is found primarily in locations that receive 6-22 in (15-56 cm) of precipitation. Cheatgrass will grow in almost any type of soil. Research has shown that it is most often found on coarse-textured soils and does not grow well on heavy, dry, or saline soils. Cheatgrass has been found growing on B and C soil horizons of eroded areas and areas low in nitrogen. It grows in a narrow range of soil temperatures. Growth starts at just above freezing and stops when temperatures exceed 60 degrees F (15 degrees C). Litter promotes germination and establishment of seedlings.


Cheatgrass is native to southern Europe, northern Africa, and southwestern Asia, where it occurs from sea level to 5,000 feet (1,500 m). This grass has been in the shadow of livestock production since ruminants were first domesticated in southwestern Asia (Young et al. 1972). It has spread to Europe, southern Russia, west central Asia, North America, Japan, South Africa, Australia, New Zealand, Iceland, and Greenland. It was first identified in the United States in 1861 in New York and Pennsylvania and was accidentally introduced to northeastern California late in the nineteenth century. In 1900 it was found in Yosemite National Park, and by 1920 it could be found along the Klamath River, near Yreka (Siskiyou County), Santa Barbara, and Upland in the South Coast (Robbins 1940). It now occurs throughout the United States (including Hawaii and Alaska), except for portions of Alabama, Georgia, South Carolina, and Florida. The hairy seed heads are spread by wind, attachment to animal fur or human clothing, or by small rodents. Contaminated grain seed probably was the early method of dispersal. Seeds can also be dispersed as a contaminant in hay and straw or by mud clinging to machinery.


Cheatgrass displaces native vegetation. It outcompetes the seedlings of native and desirable species for soil moisture. In a classic paper Robertson and Pearce (1944) determined that cheatgrass closed communities to the establishment of seedlings of perennial herbaceous species. Subsequently, it has been determined that cheatgrass also interferes with seedling establishment of shrubs such as antelope bitterbrush (Purshia tridentata) and with pine (Pinus sp.) transplants.


Cheatgrass changes the frequency, extent, and timing of wildfires. The early-maturing fine-textured herbage of cheatgrass increases the chance of ignition and the rate of spread of wildfires. Repeated wildfires lead to the loss of native shrubs and continued cheatgrass dominance (Young and Evans 1978, Young et al. 1987). Slow-moving fauna such as desert tortoises also are sometimes killed in the rapidly moving fires (Lovich, pers. comm.).


Cheatgrass establishes by seeds only. The plant typically flowers from mid-April through June. It has a tremendous seed production capacity, with a potential in excess of 300 seeds per plant, depending on plant density. Plants as small as one inch (2.5 cm) in height may produce seed. Seed production is so abundant that many seeds do not find safe sites for germination. These seeds can remain dormant in the soil for two to three years. Seeds can withstand extremely high soil temperatures. As a general rule, there are twice as many viable cheatgrass seeds in seedbanks as there are plants established in a given year. The dormancy can be broken by gibberellin treatment or nitrate enhancement of the seedbed. Through the mechanism of acquired seed dormancy cheatgrass enjoys the ecological benefits of continuous germination.

bromus tect-large2

In keeping with its flexible flowering traits, cheatgrass can germinate in fall and act as a winter annual. The primary limit to germination is adequate fall, winter, and/or spring moisture. If fall precipitation is limiting and spring moisture is adequate, germination may be delayed until the following spring. Seeds germinate best in the dark or in diffuse light, and they readily germinate at a wide range of temperatures. They do not need to be in contact with bare soil to germinate, and a litter cover generally will improve germination. However, seeds will germinate more quickly when covered with soil, and seedlings rapidly emerge from the top one inch (2.5 cm) of soil. No emergence occurs from seeds buried four inches (10 cm) below the surface.

(click on photos to view larger image)

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Shoot growth occurs in early spring and continues until soil moisture is exhausted. Cheatgrass grows rapidly and may produce dry matter at a rate of 2.9 g/mm2/day. However, growth varies widely from year to year, with practically nothing one year and tons per acre in subsequent years.

Extensive root growth can occur during fall and winter. Cheatgrass will produce roots to depths of seven to eight inches (18-20 cm) before sending out far-reaching lateral roots. These lateral roots are one key to survival of this plant. One study showed that cheatgrass has the capability to reduce soil moisture to the permanent wilting point to a depth of twenty-eight inches (70 cm), reducing competition from other species.


Physical control:

Mechanical methods: Mechanical fallows are effective in controlling cheatgrass and establishing herbaceous perennial seedlings. The fallow process accumulates moisture and nitrate to aid in seedling establishment. Tillage in spring after cheatgrass is established is effective if sufficient moisture remains for perennial seedling establishment. Mowing has been shown to reduce seed production when the stand is mowed within one week after flowering. This reduces seed production, but does not eliminate it because plants that develop later and escape mowing will produce seed.

Prescribed burning: Burning of pure cheatgrass stands enhances cheatgrass dominance. This is because wildfires often occur in late summer or fall, a poor time for perennial plants to reestablish. Open ground created by fires is readily colonized by annuals such as cheatgrass. However, burning of mixed shrub-cheatgrass stands generates enough heat to kill most cheatgrass seeds and offers a one-season window for the establishment of perennial seedlings. This is why prompt revegetation after wildfires in sagebrush communities is so important. Because cheatgrass is a cool-season annual, prescribed fire in late spring might help to control this species, especially in areas where native warm-season grasses are desired. A prescribed fire should kill seedlings and further reduce the surface seedbank. Spring burning of the closely related Japanese brome (Bromus japonicus) showed that consecutive annual burns reduced brome density and standing crop (Whisenant and Uresk 1990).

Biological control:

Insects and fungi: No insects or fungi have been approved by the USDA for use on cheatgrass. Research into the biological control of cheatgrass is limited. Cheatgrass is often infected with a head smut fungus (Ustilago bulleta Berk.) that, when severe, may reduce seed yield. Some research has been conducted on pink snow mold (Fusarium nivale) as a biological control agent, but information has yet to be released. In addition to these molds and smuts, over twenty diseases of cheatgrass have been reported.

Grazing: Grazing management systems that favor perennial herbaceous species are excellent tools in the suppression of this pest. This is a good means to avoid the risk of extensive wildfires that cause severe ecological degradation. Late fall and early spring grazing has been shown to significantly reduce plant numbers. However, heavy grazing will promote cheatgrass invasion. Encouraging the reestablishment of native plants improves the effectiveness of grazing as a

Plant competition: Biological suppression is the most cost-effective and least ecologically intrusive method of controlling cheatgrass. Cheatgrass is not competitive with established perennials, particularly grasses. Establishing native perennials is easiest after cheatgrass is removed by other control methods.

Chemical control:

Several effective herbicide techniques used in the past are no longer available. The registrations for these herbicides have either been lost or not renewed because of cost to the manufacturing companies. Glyphosate (as Roundup®, Rodeo®) applications control cheatgrass, but its effectiveness is limited by the environmental conditions during the cold early spring when glyphosate should be applied. Several newer herbicides are being tested for selective control of cheatgrass in perennial broadleaf seedling stands.

Most of the work on the chemical control of cheatgrass has focused on infestations in agricultural crops. Chemical control research in prairies has been primarily limited to atrazine. Herbicides active on cheatgrass in various crops include diclofop, atrazine, simazine, amitrole, imazapyr, sulfometuron, paraquat, and glyphosate. Many herbicides are not specific to cheatgrass or may not be specifically licensed for this use.