Russian thistle

Identification & Biology

Photo By: Lisa Scott
Russian thistle

Alias' : Tumbleweed

Latin Name : Salsola kali

Category : Terrestrial Plants

Description :

Annual with taproot
Reaches heights of up to 1.0 m tall
Mature plants rounded, bushy and highly branched
Stems are red or purple striped
Leaves are alternate; the first leaves are long, string-like and soft; later leaves are short, scale-like and tipped with a stiff spine
Flowers are inconspicuous and occur in the axils of the upper leaves
Each flower is accompanied by a pair of spiny floral bracts

Seedlings first emerge in the late spring – early summer, and look similar to grass seedlings. The seedlings are poor competitors and do not establish in communities with high plant densities. Russian thistle usually flowers from July through October. Seeds mature from late summer into the fall. Seeds remain viable for less than one year. After seeds mature in the fall, the plant stem separates from the root and the plant tumbles in the wind. The resultant brittle and spiny tumbleweeds fill drainage canals, catchments and gullies, and pile up against fences and dwellings.

Habitat

In British Columbia, Russian thistle grows at low- to mid-elevations along roadsides, railroad tracks, pastures, fields, disturbed rangeland and other disturbed habitats. It grows on well-drained, uncompacted soil with a sunny exposure. It cannot tolerate saturated soil for extended periods. Since its introduction to North America, it has become one of the most common and troublesome weeds in the drier regions of the continent.

Impact & Risks

Russian thistle can contain toxic levels of soluble oxalates and nitrates which impacts livestock, especially sheep.
It is an alternative host of several economically significant insect species.
Piles of dried, mature plants can create a fire hazard.

Prevention & Mitigation

The most effective way to ensure that your lands do not become infested with Russian thistle is by prevention. Here are some recommendations to prevent Russian thistle from invading your property:

Maintain your crops and natural lands in a healthy, vigorous condition to ensure a competitive plant community; competitive perennial grasses and forbs utilize water and nutrients that would otherwise be readily available to Russian thistle.
Regularly patrol your property for Russian thistle plants and immediately control or remove infestations before seed set. Do not leave plants to compost as they may still produce viable seed.
Cooperate with adjacent landowners and encourage them to prevent Russian thistle spread.
Immediately re-vegetate disturbed, bare soils with a suitable seed mixture that provides dense, early colonization to prevent weed invasion.
Do not move contaminated soils to a new area.

Treatment & Disposal

Small infestations can be hand pulled, mowed or hoed out.
Russian thistle can only be managed by eliminating seed production and be depleting the soil seed bank. Cull, pull, or treat plants with herbicide before seed set.
Before applying herbicides, read the label for full use and precautionary instructions.
For further information on the selection and application of chemicals to protect your crop, contact AgriService BC at 1-888-221-7141 or email AgriServiceBC@gov.bc.ca

Okanagan Distribution

Priority Level Definitions

Watch For - Poses a significant threat (very high risk) and does NOT presently occur in the region OR is relatively new to the region and is very limited in extent.

High - High risk/impact; limited population with significant potential to spread in the region.

Medium - Medium risk/impact; limited distribution – broader population distribution with potential to spread further in a region.

Low - Low risk/impact; may be widespread or not, may be of concern in specific situations with certain high values – e.g. specific agriculture crops. Some species may be treated primarily with biological control agents.

Commodities

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