Salsola tragus (Salsola iberica, Salsola kali)
Did you know?
The 'tumbling tumbleweed' of Western fame is none other than the invasive weed Russian thistle!
How did Russian thistle get here?
Western novelists, artists, and movie producers depict tumbleweeds as symbolic of the American West almost as much as cowboys. This seemingly historic icon is actually an invasive weed. Contaminated flax seed, brought by Russian immigrants to South Dakota in 1873, is thought to be the source of Russian thistle invasion. After its introduction, it became one of the most common weeds in the drier regions of the West. It spread by contaminated seed, threshing crews, railroad cars, and by windblown tumbleweeds. Ironically, Russian-thistle hay saved the beef cattle industry during the Dust Bowl of the 1930’s, when no other feed was available for starving animals.
What are its characteristics?
Russian thistle is a bushy annual forb that grows 6 to 36 inches tall and reproduces from seed. Stems are usually red or purple striped. Flowers are green and hard to recognize near the upper leaves. Seeds are spread as mature plants break off at ground level and tumble with the wind. One plant typically produces about 250,000 seeds, which may remain viable for one year. Rapid germination and seedling establishment can occur with very limited amounts of precipitation. It is often found in dryland agriculture fields, but is also common on disturbed and overgrazed rangeland.
Cattle and sheep eat Russian-thistle, and it is a minor component in mule deer and elk diets until it flowers and becomes spiny. It is an important prairie dog food, and pronghorn eat it readily. Russian-thistle seeds are eaten by birds, including scaled and Gambel's quail, as well as small mammals.
Why is Russian thistle a problem in the Great Basin?
Livestock ranges, deteriorated from drought or overgrazing, are frequently invaded and dominated by Russian-thistle. After seeds mature in late fall, the plant stem separates from the root and the plant is then blown by wind. Seeds fall to the ground as the plant tumbles. The tendency of dead plants to collect along fence lines and buildings creates a fire hazard. During a fire, ignited plants can blow across fire lines and make fighting fire more difficult.
How can we fight this weed?
Prescribed burning will not control Russian-thistle since it thrives on disturbed sites, and seeds are easily spread from unburned areas by tumbling weeds. Some herbicides are effective against Russian thistle, and current herbicide information can be found in the Weed Management Handbook on the University of Wyoming Extension website. Revegetation of infested areas, along with the removal of disturbing factors like overgrazing and fire, is the best way to repair lands infested with this weed.
-Drawing: USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. Illustrated flora of the northern states and Canada. Vol. 2: 25.
-Flower: © Joseph Dougherty/ecology.org.
-Plant: Intermountain Herbarium.
-Howard, Janet L. 1992. Salsola kali. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: (http://www.fs.fed.us/database/feis/, 26 September 2006).
-Killerplants.com. Why were Mennonites blamed for a Russian invasion? Available: (http://www.killerplants.com/plants-that-changed-history/20020702.asp 27 September 2006).
-USDA, NRCS. 2006. The PLANTS Database (http://plants.usda.gov, 26 September 2006). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
-Whitson, T. D., et.al. 2000. Weeds of the West., 9th ed. Western Society of Weed Science, Newark, CA.