Russian thistle, commonly known as the tumbleweed, is a profusely branched annual herb. Its efficient taproot, abundant seed production, and reduced leaf surface helps it to adapt to semiarid agricultural environments, rangeland, and nonagricultural areas such as vacant resident lots, and railroad or highway rights-of-way. It has become pervasive as an interloper weed throughout California and the western United States.

Dry Russian thistle plants are a serious fire hazard. This weed spreads easily because it breaks off at ground level and tumbles across open land scattering seeds for miles. Quickly taking over habitats of native plants makes the tumbleweed concerning because diversity in native species is greatly reduced.

Furthermore, Russian thistle is a nuisance in agricultural areas especially in small grain and alfalfa fields. By depleting available water for crops and providing shelter to harmful invertebrates the Russian thistle reduces crop yield. Another agricultural issue created by the Russian thistle is it acts as an alternate host for the virus beet leafhopper. This virus causes curly top disease in melons, tomatoes, sugar beets, and other crops. 

A fire hazard is created because the Russian thistle can build up along fence lines where it must be manually removed. It is capable of facilitating fire spread when ignited while rolling across the landscape.

In addition to being a nuisance, Russian thistle is an expense to both public and private property owners. While the economic impact has not been well documented, costs include clean-up of public roadways, loss of seed crops due to contamination by thistle seed and illness or even death of foraging livestock, and degradation of valuable and highly diverse wilderness areas.

So where and when did this invasive weed come from? Russian thistle is a summer annual native to southeastern Russia and western Siberia and was originally introduced into the United States as a contaminant of flax seed in South Dakota in 1873. Within 20 years, it had spread to 16 western states and several Canadian provinces. It is now widespread throughout western North America, including virtually all arid and semi-arid regions. Russian thistle infests around 100 million acres of land.

Control methods have been tried and are being discussed. Some claim Russian thistle is an exotic weed species and is a good candidate for biological control. A pith-boring moth and a case-bearing moth have been determined to be biocontrol agents but are ineffective. Mites, moths, and beetles that exhibit sufficient host specificity may potentially be effective natural enemies of this weed. Phytopathogens may also offer promise and should be investigated as possible biological control agents.

Of great concern are controversial discussions and research efforts to control or eradicate Russian thistle. Some experts are pushing back against some proposed biological control. The controversy lies in introducing additional insect enemies from the weed’s native lands. The effects could be detrimental to our native insect population.

If you find this weed on your land cut it down close to the roots while it is young. It may take a couple of seasons to get rid of the Russian thistle from your land, but persistence will pay off.