Downy Brome Control

Downy brome (Bromus tectorum L.) was introduced into North America from the Mediterranean area of Europe. In 1861 it was identified in New York and Pennsylvania, and by 1914 it had spread throughout North America. It has maintained its current distribution since about 1928. Downy brome has become established throughout Nebraska and is one of the most serious weeds in western Nebraska. It is especially troublesome in alfalfa, winter wheat-fallow rotation, continuous winter wheat, rangeland, waste areas, roadsides, shelterbelts, fence rows, and railroad rights-of-way. It invades overgrazed pastures and rangelands and is spread when the long awns on seeds attach to cattle. Seeds also are spread by hay, combines, grain trucks, and in contaminated winter wheat seed.

Downy brome is known by a variety of names including cheatgrass, cheatgrass brome, downy bromegrass, military grass, wild oats, downy chess, and cheat. Two other annual bromes often are confused with downy brome: Japanese brome (Bromus japonicus Thunb. ex. Murr), which is more common in western Nebraska, and hairy chess (Bromus commutatus Schrad), which is more common in eastern Nebraska. Both are more prevalent in pastures and waste areas but can be found in winter wheat. This discussion of downy brome also pertains to Japanese brome and hairy chess.

Downy brome thrives in all soils. This weed has an extensive shallow root system and roots with many hairs which enable the plant to extract much of the soil water. A downy brome density of 50 plants per square foot can remove soil water to the permanent wilting point to a depth of about 2.5 feet. Downy brome is thus very competitive with winter wheat for soil water and nutrients. Under stress the plants can produce seed when they are only 1 to 2 inches tall. Plants under stress from tillage or harsh environments divert more of their photosynthetic capabilities to seed production than undisturbed plants or plants growing in more productive environments.

Being a winter annual, downy brome is a constant threat to winter wheat, alfalfa, and rangeland. Under certain climatic and field conditions, it can seriously hinder winter wheat production. At Alliance and North Platte, moderate (one to two plants per square foot) to heavy infestations reduced wheat yields 30 to 80 percent. Both yield and quality of alfalfa in infested fields often will be lowered. Overgrazed rangelands are more easily invaded by downy brome which reduces economic returns of the grassland.

Downy brome is a palatable grass before the seed heads emerge but becomes unpalatable with maturity. Mature downy brome can cause injury to livestock by causing infection in the eyes or mouth. Mature plants are also a serious fire hazard.