Species specifics: Broom snakeweed

Fast facts

Highly toxic to cattle, particularly to heifers or cows in gestation
Noxious and prevalent throughout the dry rangelands of the western U.S.
Small woody perennial that will aggressively invade disturbed or overgrazed pastures

What to look for

Broom snakeweed (Gutierrezia sarothrae) is a warm-season small woody perennial weed found throughout dry rangelands of western U.S. that is highly toxic to cattle, particularly cows and heifers in gestation.

The native plant features a woody base with numerous slender and erect stems that are somewhat brittle and have small linear leaves with smooth edges. Broom snakeweed averages 18 inches tall but can grow up to 40 inches in certain conditions and can live up to 20 years. New stems grow from the crown each year rather than old regrowth, as is common of other similar-looking woody shrubs such as rabbitbrush. Small, round, inconspicuous yellow-ray flowers appear from July to September. It can produce up to 10,000 seeds annually that are small and light – ideal for wind dispersion – and can remain viable in soils for years. Seeds germinate as soil temperatures rise and daylight increases in late winter and early spring. The weed prefers dry rangelands where soils are sandy, chalky or dense with clay and has no problem surviving droughts. Broom snakeweed will aggressively spread in abused or recently disturbed rangelands, such as from overgrazing or fires.

Cattle tend to avoid the weed but will readily consume the weed if other food sources are scarce. Females in gestation tend to be most susceptible to broom snakeweed toxicity, as the toxin in the plant is abortifacient. The plant is also a secondary absorber of selenium from the soil it is growing in which can lead to toxic levels of the micromineral in areas where selenium is naturally high in the ground. Toxicity from broom snakeweed consumption can lead to numerous adverse effects, including abortions, weak calves, retained placentas and a cascade of other physiological responses, including death. Bulls, steers or dry females can also be affected, as well as other livestock species like sheep and goats. Toxicity can vary in degree depending on the time of year, with the highest being during leaf formation in early spring (January – April).

Where it is found

Due to its preference for dry climates, broom snakeweed is common throughout the Southwest, as well as the dry mountain basins of the western Great Plains and the lower Rocky Mountains. States where ranchers commonly fight broom snakeweed include Arizona, southern California, Colorado, southern Idaho, New Mexico, Nevada, southeast Oregon, west Texas, Utah and southern Wyoming.

How to treat it

The tough weed should be treated with herbicides in fall during full bloom, as spring applications will likely only suppress the plant. Apply 3 ounces of Chaparral™ herbicide per acre OR 1 pint of Tordon® 22K herbicide per acre.

Tordon® 22K is a Restricted Use Pesticide. Chaparral™ has no grazing or haying restrictions for any class of livestock, including lactating dairy cows, horses (including lactating mares) and meat animals prior to slaughter. Label precautions apply to forage treated with Chaparral and to manure and urine from animals that have consumed treated. Consult the label for full details. Chaparral is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Tordon 22K is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Always read and follow label directions.