Synonym(s): Salsola australis, Salsola iberica
Family: Chenopodiaceae (Goosefoot Family)
Duration and Habit: Annual Herb
Noxious bushy summer annuals, with rigid branches and reduced, stiff, prickly upper stem leaves (bracts) at maturity.
Native Lookalikes: Currently no information available here yet, or there are no native Texas species that could be confused with Russian thistle.
Ecological Threat: Plants are an alternate host for the beet leafhopper (Circulifer tenellus) that can carry the virus causing curly-top of sugarbeets, tomatoes, melons, and many other crop and native plants. Immature plants can provide extra forage for livestock on arid rangelands. However, under certain conditions, such as heavy nitrogen fertilizer application, nitrates or oxalates can accumulate to levels poisonous to sheep.
Biology & Spread: Most seed germinates the spring following maturation. Seed can germinate when night temperatures are below freezing and daytime temperatures reach 2? C. Optimal temperatures for germination are between 7 and 35? C (45 and 95? F). Germination requires little moisture (0.3 inches of rainfall) and occurs within in a few hours. Successful germination requires loose soils. Seedlings that germinate on firm soil seldom survive because radicles are unable to penetrate the soil. Seed in the field typically remains viable for only 1 year, some up to 2 years, rarely to 3. Plants about 0.5 m tall can produce about 1500-2000 seeds, and large plants can produce up to 100,000. Seed disperses when plants break off at ground level and tumble with the wind. Seedlings attain optimal emergence from litter or soil depths to 1 cm, but can emerge from soil depths to 6 cm.
History: Introduced from Eurasia.
U.S. Habitat: Typically infests sandy soils on disturbed sites, waste places, roadsides, cultivated and abandoned fields, disturbed natural and semi-natural plant communities.
U.S. Nativity: Introduced to U.S.
Native Origin: Africa, temp.& trop. Asia, Europe (Germplasm Resources Information Network)
U.S. Present: AL, AR, AZ, CA, CO, CT, DE, GA, HI, IA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VA, VT, WA, WI, WV, WY
Distribution in Texas:
List All Observations of Salsola tragus reported by Citizen Scientists
Glasswort [Salsola soda L.] is a slender erect to rounded, glabrous summer annual, to 0.5 m tall. Unlike the Russianthistles, Glasswort remains fleshy at maturity, has calyces 3.5-5 mm long, with inner sepals (facing stem) tubercled and outer sepals with wings less than 1.5 mm long. It is an introduced weed of mudflats and saltmarshes in the San Francisco Bay region. Although flowers and fruits resemble those of Russian and barbwire Russianthistle, Mediterranean saltwort [Salsola vermiculata L.][SASVE][CDFA list: A] is easily distinguished by its shrubby perennial habit and oblong to ovate leaves with rounded tips. It is an uncommon weed of disturbed rocky slopes and flats, often on clay soils, in the Temblor Range (se San Luis Obispo and possibly cw Kern cos.). To 1000 m (3300 ft). Introduced from Syria in 1969 as an experimental range plant. Immature halogeton [Halogeton glomeratus (M. Bieb.) C. Meyer] is distinguished from immature Russianthistles by having fleshy cylindrical leaves broadest near the tips and tufts of long white hairs in the leaf axils.
Prevention: These thistles are part of a complex genus in the Chenopodiaceae family. They are strongly competitive in semiarid areas and are heavily favored by disturbance. They persist in dryland cropping systems, overgrazed rangeland, roadsides, and waste areas. The exact time of introduction into California for Salsola tragus and Salsola paulsenii is uncertain, but may have been near the turn of the century. Salsola collina is not currently present in California, but appears to be increasing its range across the Great Plains.
Mechanical: Many mechanical strategies are effective in controlling these thistles. Mowing is effective on very young plants. However, older plants will recover by axial branching below the cutting level. Plants should never be mowed after seed set has occurred, as this will facilitate seed dispersal to new areas. Tillage will control both seedling and larger plants. However, tillage increases disturbance, which favors additional germination of seeds. Seed viability appears to be 1-3 years for Russian thistle and is unknown for barbwire or spineless Russian thistle. Therefore, an intensive tillage program that completely prevents seed production for 2-3 years may eliminate these thistles. However, recurrent seed depositions from tumbleweeds blowing in from adjacent areas is highly probable.
Hand pulling of large plants is extremely difficult and may be injurious due to the spiny nature of Russian and barbwire thistle. Always wear gloves if attempting to hand pull these species.
Biological: There are two insects that have been approved and released for control of Russian thistle: a leaf mining moth (Coleophora klimeschiella) and a stem boring moth (Coloephora parthenica). Both are available for release in California. Beyond its known establishment in central California, there is little information on the effectiveness of Coleophora klimeschiella. Coloephora parthenica has not been effective in reducing Russian thistle populations. There are a number of possible factors for this, including predation by rodents, spiders, and parasitoids; poor host plant synchronization due to herbivore independent mortality; and a general lack of effectiveness in reducing seed production. Recent taxonomic reconsideration of Salsola tragus and its possible biotypes or subspecies may bring further clarity to the effectiveness of this biocontrol agent.
Chemical: These thistles primarily occur in dryland agricultural production systems, roadsides, rangelands, and waste areas. This presents the need for several different herbicide strategies. Generally, seedling Russian thistle is not difficult to control with the proper herbicides. However, as plants get older, moisture stress is often likely and herbicide efficacy is greatly reduced. For roadsides, preemergent herbicides applied in the fall can provide season long control. Table 1 provides effective herbicides for roadside Russian thistle control. Post-emergent applications should be made in the seedling stage for effective control. Postemergent applications generally do not provide long term control due to repeated flushes of seed germination following herbicide application. Consult the label for application rates and restrictions.
Russian thistle has documented resistance to chlorsulfuron in Idaho, Oregon, and Washington. In California, a biotype with resistance to both chlorsulfuron and sulfometuron has been found. Avoid developing resistance by using a combination of management strategies and rotating between herbicide modes of action.
Encycloweedia, California Department of Food and Agriculture
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