Prickly Russian Thistle, Tumbleweed, Witchweed
Description
Russian thistle, Salsola tragus L., Salsola iberica Sennen, introduced from Russia, is a summer annual in the goosefoot family that reproduces by seed. Seedlings have long, threadlike leaves, resembling pine tree seedlings. It is a rounded, bushy, ulti-branched plant that can grow up to 4 feet tall and nearly as wide. Stems and branches often have reddish or purplish stripes. The numerous branches are slender and succulent when young, but woody at maturity. Leaves are alternate and linear; early leaves are dark green and fleshy, but as plants mature, leaves become short, stiff, and spiny. Flowering occurs from midsummer to fall, when small, inconspicuous, pink to greenish flowers develop and are borne, usually singly, in leaf axils above small, leaf-like, spine-tipped bracts. Russian thistle plants break off at the base after maturity and tumble with the wind, scattering seeds over great distances. A single plant can produce 250,000 seeds, which typically remain viable for a year. Seeds are round, snail-shaped, and white to pinkish in color. Russian thistle is commonly found in dryland fields, along roadsides, and in disturbed areas. It can reduce yield and quality of crops. Despite the many downsides of Russian thistle, young plants can be used as livestock forage. Russian thistle actually provided a lifeline to beef cattle during the Dust Bowl era, when animals were starving due to a feed shortage.
Photo by Steve Van Vleet, WSU Extension: Whitman County
Control Methods
Mechanical: Mechanical strategies can be used to manage Russian thistle. Small infestations of young plants can be pulled or dug. Little can be done with mature plants, not only because of their large size and spiny nature, but because disturbance facilitates seed spread. Mowing is not effective unless repeated often for several years because plants tend to recover by sprouting new branches below the cutting level. Ongoing intensive tillage that prevents seed production can control Russian thistle, particularly when combined with cultural practices, i.e., maintaining competitive vegetation.
