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Cheatgrass (Bromus Tectorium L.), also known by a variety of names including downy brome, military grass, downy cheat and downy bromegrass, is one of the most problematic weeds throughout Montana. As a winter annual grass, cheatgrass is particularly troublesome in continuous winter wheat, winter wheat-fallow rotations, alfalfa, CRP lands, rangelands, fencerows and railroad right-of-ways. Not only does cheatgrass reduce crop quality and yield, it creates serious fire hazards after it matures in late spring. Although cheatgrass is palatable as spring and fall forage before emergence of seed heads, mature plants decline in forage quality and can injure livestock by causing infection in the eyes or mouth.

How does cheatgrass grow? Annual plants such as cheatgrass grow from seed, then flower, set seed and die every year. Cheatgrass is considered a winter annual plant because it usually germinates in the fall and grows rapidly until cold temperatures arrive. Germination may occur in spring as well, depending on conditions. Growth may continue through the winter, especially in the root system. In early spring, cheatgrass seedlings resume growth, produce seeds and die sometime between mid-July and early August. Winter annual weeds are particularly problematic in winter annual crops.

Damage and Impacts: As a winter annual, cheatgrass gains a competitive advantage on crops and rangeland species that may not grow very much through the fall and winter and do not begin growth as early in the spring. Soil water depletion is one of the primary mechanisms by which cheatgrass competes with perennial vegetation. This is especially problematic when attempting to revegetate land infested with cheatgrass. As spring precipitation diminishes and summer temperatures rise, perennial grass seedlings may not be big enough to survive, while cheatgrass plants are already producing seed to continue the next generation.

Because cheatgrass seeds usually do not remain viable in the seedbank for more than a couple years, preventing seed production in the spring reduces the number of seeds in the soil which may improve the outcome of integrated management. As with other weeds, preventing and minimizing invasion is critical.

Integrated Management of Cheatgrass:

In general, integration of chemical management tools with cultural practices is recommended for successful control. Practices like prescribed grazing, irrigation management, and nutrient management will help maintain the vigor of desirable species and prevent an increase of cheatgrass.

* Chemical management tools: Contact your local MSU Extension Agent for more information.

Article source: “Cheatgrass: Identification, Biology and Integrated Management“, Menalled, F; Mangold, J and Davis, E, MSU Extension MT200811AGNew 10/08

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