ABSTRACT
Broom snakeweed, Gutierrezia sarothrae, is an evergreen suffrutescent shrub common on western rangeland from Canada to Mexico. Broom snakeweed populations are cyclic with high numbers of plants growing when there is enough soil moisture, and decreasing dramatically during drought or stress. Dense broom snakeweed stands cause significant economic losses to ranchers in the plains, prairie, and desert areas of central and southwestern United States. Native grass production is often 100 to 800% higher on snakeweed-free rangeland compared to yield under a dense snakeweed stand. Calf losses on snakeweed-free sandy range sites in eastern New Mexico are reported to average 3 to 4%, whereas on snakeweed infested rangeland, losses can approach 60% in some herds. Selenium poisoning may also occur from broom snakeweed plants growing in soils with a high selenium content. For a mature, vigorous broom snakeweed plant growing in central Texas, growth of perennating buds usually begins in November and December, immediately after flowering and seed set.
