Identification and Management of Kochia and Russian Thistle Fact Sheet No. 6.314 Natural Resources Series|Forestry by S. Bokan, K. Crumbaker, and G. Beck* Weed Description normally have red or purple striping. When Quick Facts Kochia (Kochia scoparia L.) and Russian seedlings first emerge they look similar to • Read and comply with all thistle (Salsola tragus L.) are troublesome grass seedlings. The leaves are alternate, herbicide labels, organic or annual weeds of rangelands, pastures, small, narrow and appear scale-like with a fields, disturbed areas, gardens, roadsides, stiff spine. The flowers, accompanied by a nonorganic, for application ditchbanks, and small acreages. Both species pair of spiny, floral bracts, are green and very rates, mixing instructions, are non-native to the United States. Kochia, a inconspicuous. Russian thistle dries out and protective equipment, re-entry native of Asia, was introduced from Europe. becomes a tumbleweed, spreading seeds as it period, grazing or harvest Russian thistle originated in Russia and rolls with the wind across landscapes. restrictions and other safety was brought to the U.S. in the late 1800’s as information. a contaminant of North Dakota flax seed. Livestock Poisonings Kochia is found in all western states except • Kochia and Russian thistle, Nitrate, oxalate, sulfates, saponins, and Alaska. Russian thistle is found in every which are summer annuals, alkaloids are found in kochia at levels that state in the U.S., except Alaska and Florida. are troublesome annual can cause poisoning in cattle and sheep. Both plants reproduce only from seed; weeds of rangelands, While it can be used as forage in some areas, therefore preventing seed-set is important pastures, fields, disturbed other forage species should also be available for successful management. Competition areas, gardens, roadsides, to avoid the possibility of livestock poisoning. from desirable plant species will limit Russian ditchbanks, and small The likelihood of poisoning increases as the thistle and kochia establishment and site plant matures or when drought stressed. acreages. If uncontrolled, they dominance. Russian thistle can accumulate toxic levels become tumbleweeds that Kochia is a summer annual plant, with of nitrates which can cause acute respiratory can disperse seeds over a many branches forming pyramidal or conical difficulty and sudden death in cattle and large area. shaped bushes 6 ft. tall or greater. Leaves are sheep. Russian thistle contains oxalates, small, fuzzy and gray-green in color. Leaves • Nitrate, oxalate, sulfates, which may result in kidney failure in cattle on older plants are alternate, linear shaped saponins, and alkaloids are and sheep if ingested. and 0.5 to 2 in. long and often hairy. The found in kochia at levels that stems are highly branched and green or red can cause poisoning in cattle tinged. When the seedlings germinate in Uses and Values and sheep. The likelihood the spring, infestations appear to be a gray- Kochia may provide good forage quality of poisoning increases as green mat. Kochia typically will germinate when the plant is young, however, the forage the plant matures or when many times during the growing season, quality declines as the plant matures. The often beginning in March with last flushes drought stressed. value to wildlife is shared by many species. occurring from August to early September. Deer and pronghorn eat the foliage; seeds • Russian thistle can Flowers are inconspicuous. Seeds are are consumed by songbirds and upland accumulate toxic levels of dispersed when the plant matures and stems game birds. Kochia also provides loafing and nitrates which can cause break off at the base; the plant then becomes nesting cover for upland game birds. acute respiratory difficulty and a tumbleweed. Russian thistle is fair forage when the sudden death in cattle and Russian thistle, a large, bushy, prickly plant is young. When the plant matures, it summer annual weed, can grow to 3 ft. tall. sheep. becomes unpalatable due to the spike-like The stems are erect, many-branched and inflorescence. When mature, Russian thistle provides excellent cover for pheasants, while ©Colorado State University *S. Bokan, Colorado State University Extension, small Extension. 12/12. acreage coordinator; K. Crumbaker, agent, agriculture small mammals and songbirds will feed on and natural resources;G. Beck, Extension specialist, the seeds and foliage. www.ext.colostate.edu weed science, and professor; 12/12 the young plants from the soil. Mowing prevent new contributions to the soil seed or cutting are limited options and must be reserve. Pulling the plants at later stages timed to prevent the plant from regrowing may require wearing gloves for comfort, and producing seed. Kochia will continue due to the spike-like inflorescence. In fields, to produce seed on branches below mowing light tillage can disrupt the young plants levels. Maintaining healthy pastures or from the soil. Mowing is a limited option fields will keep kochia from establishing. that must be timed to prevent the plant Herbicides that will control kochia from being able to regrow and produce effectively include fluroxypyr (sold under seed, and is best done when the plant the trade names of Vista and Starane), is beginning to bloom. Desirable plants Figure 1. Russian thistle seedling. dicamba, and glyphosate. Fluroxypyr and may be damaged if mowing is too low. dicamba are selective herbicides that will Maintaining healthy pastures or fields will control broadleaf weeds and typically prevent the establishment of Russian thistle. not injure grasses. 2,4-D, that is often Herbicides that will control Russian applied for kochia control, is not effective. thistle include 2,4-D, dicamba, or Glyphosate is a non-selective herbicide that glyphosate (sold under the trade name injures or kills most vegetation contacted. Roundup). Dicamba and 2,4-D are selective Glyphosate is especially effective for herbicides that will control many broadleaf controlling large kochia. Kochia biotypes weeds but usually do not injure grasses. resistant to glyphosate have been found, Glyphosate is a non-selective herbicide that particularly in wheat-growing regions. can injure or kill most vegetation contacted. Control from herbicides is best when Chemical control is best applied in the Figure 2. Kochia seedlings. applied when plants are small and in the spring when plants are rapidly growing. 2-6 in. stage rather than on small fuzzy Organic chemicals can be used, such seedlings with little leaf surface area. Use of as those containing acetic acid or clove a non-ionic surfactant is recommended to oil. These organic herbicides are contact allow the herbicide to penetrate the hairs materials and largely non-selective, but and reach the leaf surface. Methylated seed will not control perennials. They are also oil at 1 to 2 qt/A is recommended when corrosive to skin and respiratory systems. using fluroxypyr to control large kochia Read the label before purchasing or using plants. the product. Organic herbicides, such as those For best results on a stand where containing acetic acid or clove oil, can both species are present, use a mixture be used to control kochia. These organic of dicamba plus 2,4-D, or dicamba plus Figure 3. Mature kochia. herbicides are contact materials and fluroxypyr (Vista). largely non-selective, but will not control Read and comply with all herbicide perennials. They are corrosive to both skin labels, organic or nonorganic, for Integrated Weed and respiratory systems. Read the label application rates, mixing instructions, Management before purchasing or using the product. protective equipment, re-entry period, Recommendation Due to the hairs on the kochia leaves, the grazing or harvest restrictions and other use of surfactants will aid organic herbicide safety information. The first step to controlling either of absorption. these plants is to keep current plants from Russian thistle is easily pulled or hoed References producing seed that is added to the seed out, at early growth stages. If plants have repository in soils. Limit disturbances such already started producing seed, it is best to on next page as tractor, animal and people traffic through collect the plants and dispose of them to infested areas to decrease its spread. Remove tumbleweeds from fence lines to keep plants from continuing to spread seed. Kochia has a shallow taproot and can Table 1. Herbicide Treatments be easily pulled or hoed out at early growth Kochia Dicamba: Banvel, Clarity, Fluroxypr: Vista stages. If it has already started producing Vanquish 1-2 pt/A 1-2 pt/A; use higher seed, it is best to collect the plants and rate for large plants dispose of them, preventing further soil Russian thistle Dicamba: Banvel, Clarity, 2,4-D Glyphosate: Roundup infestation. In fields, light tillage can disrupt Vanquish 1-2 pt/A 1 qt/A 1-1.5 qt/A References Knight, Anthony P., Walter, Richard G., 1st Edition, 2001, A Guide to Plant Poisoning of Animals in North America. Stubbendieck, James, Geir Friisoe, Margaret Bolick, 3rd Edition, 2003, Weeds of Nebraska and the Great Plains, Nebraska Department of Agriculture. Whitson, Tom, Larry Burrill, Steven Dewey, David Cudney, B. Nelson, Richard Lee, Robert Parker, 9th Edition, 2006, Weeds of the West, the Western Society of Weed Science. Colorado State Parks, Best Management Practice, Weed Profile, Russian thistle, http://parks.state.co.us/ SiteCollectionImages/parks/Programs/ ParksResourceStewardship/Russian%20 Thistle.pdf. Larimer County Weed District, 4th edition, Weed Management Reference Guide, www.larimer.org/weeds/weed_ management_guide.pdf. USDA NRCS, Plants Database, Plant Guide Kochia http://plants.usda.gov/ plantguide/pdf/pg_basc5.pdf.

Colorado State University, U.S. Department of Agriculture and Colorado counties cooperating. CSU Extension programs are available to all without discrimination. No endorsement of products mentioned is intended nor is criticism implied of products not mentioned.