Crop, Range, Pasture

Cheatgrass (Bromus tectorum)

Monica Pokorny

Steve Dewey, USU, Bugwood.org Mature nodding cheatgrass panicle with awned spikelets.

L.J. Mehrhoff, U of CT, Bugwood.org Cheatgrass infestation.

Identification and Life Cycle. Cheatgrass, also known as downy brome, is an introduced annual or winter annual grass (Poaceae). Seedlings are bright green with hairy leaf blades and sheaths. Mature plants are generally 4-30 inches tall with a finely divided, fibrous root system that may reach 12 inches deep. Stems are erect, slender, glabrous, or slightly hairy. Leaves are light green and hairy with fused sheaths except near the node at the bottom of each sheath. The lower sheaths are conspicuously hairy, while the upper sheaths are sometimes smooth. Cheatgrass changes color from green to purple to brown as the plant matures and eventually dries. The nodding, open panicles with moderately awned spikelets are very distinctive.

Habitats. Cheatgrass grows in both disturbed and undisturbed grasslands, shrublands and dry forests. It can tolerate a wide range of precipitation and temperature variations. Cheatgrass grows on almost any soil type but has been reported to prefer coarse-textured soils and does not flourish on extremely heavy or dry soils. It is common in recently burned rangeland, winter crops, disturbed areas, abandoned fields, eroded areas, and heavy-grazed grasslands.

Impacts. Cheatgrass can be troublesome in winter wheat and other crops. Awns many injure livestock and animals’ eyes, throat and mouths if consumed in late spring or summer, leading to reduced feed intake and weight gain. Cheatgrass can form dense stands, reducing desired forage species. Cheatgrass is adapted to and promotes frequent uniform fires. This fire cycle significantly reduces the ability of perennial grasses and shrubs to re-establish, and furthers the dominance of cheatgrass. Areas dominated by cheatgrass have increased surface soil erosion and loss of soil nutrients.

Biology and Ecology. Cheatgrass is an annual that can germinate in autumn or spring when soil moisture is adequate. Autumn-germinated plants will establish a root system that allows the plant to take early advantage of spring moisture. The seed heads appear in mid-spring, followed by flowering within a week, and seeds mature in mid to late June. Cheatgrass can produce up to 400 lbs seeds/ac. Seeds have a high germination rate and a low retention in the soil. Seeds are dispersed short distances by wind, and long distances by attaching to fur or clothing. Dry conditions can cause environmentally induced dormancy, which may last several years.

Management Approaches. Integrated management will require a combination of chemical control, cultural control, seeding perennial grasses, and proper land management.

Biological Control. none

Mechanical and Cultural Control: Controlled livestock grazing can help regulate cheatgrass populations, but grazing prescriptions depend on the mixture of plants in the plant community and timing of grazing. Repeated mowing every 3 weeks during spring and summer can be effective at managing seed production. Many cut plants will however continue to produce seed. Repeated fire treatments can be used if plants are burned after they have dried but before the seeds have dropped. Repeated pulling cheatgrass plants in small infestations before seed set can effectively eliminate current seed production, but may not eliminate the infestation. Pulling should remove as much of the root as possible. Live plants can be tilled/disked in the spring and fall before the heads turn purple. Tilling should be repeated when new plants appear. Seeds can be tilled/disked in the late spring to bury the seeds and prevent germination. Tilling should be followed by revegetation. Prevent new infestations by minimizing disturbance and seed dispersal and maintaining vigorous perennial plant communities. Revegetate disturbed areas to perennial grasses to provide competition.

Chemical Control: There are several types of herbicides that can be used alone or combined to provide effective control.

Example of herbicides that can be used to manage cheatgrass. Consult herbicide labels for additional rate, application and safety information. Additional herbicide information can be found at http://ces.uwyo.edu/WeedManagementHandbook.asp

Herbicide Trade Name chemical name	Product per Acre	Comments
Croplands
Assure quizalofop	5 - 12 oz/ac	In canola, apply to emerged weedy grasses within height ranges specified on label. For best results, apply when grasses are in the 3-leaf stage.
Frontier dimethenamid	14 - 21 oz/ac	In grass seed apply in the fall prior to emergence of targeted weeds, or in a sequential use program with other herbicides that control emerged weeds. Grass seed crop must have been established for at least 1 year or had at least one seed crop harvested before application.
Gramoxone^R paraquat	Corn/sorghum: 0.7- 4 pt/ac Peas/lentils: 1.3 - 2.7 pt/ac Sugarbeats:1.25 -3 pt/ac	In corn, peas, lentils, sugarbeats or sorghum, apply before, during, or after planting but before crop emergence and after weeds have emerged. May apply as a postemergence directed spray when crop is at least 10 inches tall.
Kerb pronamide	1 - 4 lb/ac	Apply in the fall to new fall- or spring-planted forage legume seedlings after they have reached at least the trifoliate leaf stage, or, to established forage legumes in the late fall or early winter after soil temperatures fall below 55º F, but before freeze-up.
Maverick sulfosulfuron	0.66 oz/ac in a single application	In small grains apply either preemergence or after wheat emerges but prior to jointing. Can be applied in fall or spring, but fall applications are most effective.
Nortron ethofumesate	2.25 - 7.5 pt/ac	In sugarbeats apply preplant incorporated or preemergence.
Poast sethoxydim	1.5 - 2.5 pt/ac	In canola, apply to actively growing grasses at the appropriate stage of growth indicated on the label.
Princep simazine	2.2 - 4.4 lb/ac	In corn or sorghum, apply before, during, or after final seedbed preparation, but before weeds and crop emerge.
Prism, Select, Arrow clethodim	13 - 34 oz/ac Prism or 6 -16 oz/ac Select or Arrow	May be applied to seedling or established alfalfa. Apply postemergence to weeds that are actively growing and at the appropriate growth stage listed on label.
Raptor imazamox	4 oz/ac	In peas and lentils apply postemergence when weeds are actively growing and before they exceed the maximum recommended size stated on label. Apply when peas have at least 3 pairs of leaves, but before bloom.
Roundup glyphosate	12 fl oz to 5 qt/ac	Apply to actively growing weeds before planting, or any time prior to emergence of crop.
Scythe Pelargonic acid + related fatty acids	3- 10% per 100 gallons total spray solution	In peas, lentils, potatoes, or grass seed, apply to small emerged weeds prior to crop emergence or after harvest.
Select clethodim	6 - 16 oz/ac	In potatoes and sugarbeats apply postemergence to actively growing grasses.
Sencor metribuzin	0.33- 1.33 lb/ac, or 0.5- 2.0 pt/ac; Small grains: 1.5 – 16 oz/ac	Apply in fall or spring when alfalfa or grass seed is dormant. Apply preemergence or postemergence in potatoes. In small grains apply postemergence to healthy, actively growing wheat at the 2-leaf to 4-tiller stage. Application must be made prior to the jointing stage, or crop injury may result.
Sinbar terbacil	0.5 -1.5 lb/ac	Apply in fall after alfalfa becomes dormant or in the spring before growth. Apply before or after weeds emerge, but before they are 2 inches tall.
Treflan trifluralin	1 - 2 pt/ac, or 20 lb/ac	Apply to established alfalfa during dormancy or semi-dormancy in the fall or spring before weeds emerge, or apply liquid formulations during the growing season immediately after cutting. In peas and lentils, apply preplant incorporated in the spring. In potatoes apply after planting, before emergence, immediately after drag-off, or after potato plants have fully emerged. In safflower preplant incorporated fall or spring. Apply to sugarbeets when they are 2 to 6 inches tall and well rooted so the plants can withstand incorporation.
Triflurex trifluralin	0.75 to 2 pt/ac	In corn or sorghum, apply post-emergence following cultivation and/or use of another herbicide to remove existing weeds. Crop must be well established.
Velpar hexazinone	1 - 3 qt/ac	Apply in the fall after alfalfa becomes dormant or in the spring before alfalfa growth begins.
Pasture, Rangeland, and Non-crop areas
2,4-D
Aatrex^R atrazine	1-2 pt/ac 4L; 0.63-1.25 lb/ac 80WP; 0.55-1.1 lb/ 90 DG	Apply in fall after perennial grasses are dormant but before cheatgrass has emerged. Moisture is required to activate the atrazine, which is effective as a preemergent treatment. Do not apply to perennial grasses that are not dormant.
Gramoxone^R paraquat	26 oz/ac	Apply when cheatgrass has initiated seedhead formation but before seed set. This treatment timing allows for control of both fall and spring germinating.
Journey imazapic + glyphosate	10.7 - 32 oz/ac	Apply in fall preemergence or early postemeregence.
Plateau imazapic	2-12 oz/ac	Cheatgrass control is best with applications in the late summer to early fall before it has emerged. Apply with MSO at 1 qt/ac if cheat grass has emerged.
Roundup glyphosate	12 – 16 oz/ac	Annual weeds are best controlled when they are small, actively growing, and when cheatgrass has initiated seedhead formation but before seed set. Cheatgrass can be selectively controlled with the lower rates in range and pasture if the proper conditions are met.
^RRestricted Use Product.
Disclosure. The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.

Categories: Weed, Crop, Range, Pasture, Downy brome

Date: 11/28/2007