ABSTRACT
Broom snakeweed and threadleaf snakeweed are aggressive weeds common on western rangelands from Canada to Mexico. Most cases of snakeweed poisoning occur in late winter or early spring when other herbaceous forage is depleted by winter grazing. Broom and threadleaf snakeweed are extremely variable in morphology, phenology, population density, and presumably physiology. Broom snakeweed is the most widely distributed North American species of the genus Gutierrezia and is the only perennial species common throughout the central plains and prairie regions. In New Mexico and west Texas, moderate to dense infestations of broom, and occasionally threadleaf snakeweed grow on open grassland regions found in these states. Soils where very dense broom snakeweed stands grow are characteristically shallow sandy loam to loam and underlain by caliche or limestone bedrock. Mechanical, biological, and burning methods have been used to control broom and threadleaf snakeweed but, in general, herbicides are the most common and practical method for yielding immediate range improvement results.
