Scotch thistle is listed as a noxious weed in 14 states, meaning it is designated for control and is prohibited and banned. This will avoid costly, long-term control efforts. Scotch thistle is a prolific seed producer. Stems have vertical rows of prominent, spiny, ribbon-like leaf material or wings that extend to the base of the flower heads. Small areas can be dug out. Scotch thistle is found in any type of habitat but normally establishes quickly in disturbed areas dominated by annual plants such as cheatgrass (Figure 4). Mature plants can reach a height of 8-12 feet tall. Mowing plants with visible seed heads will not prevent seed production. Nebraska Extension has a number of publications on management of thistles and other invasive species. Spray early as plants with visible seed heads will still produce viable seed. Scotch thistle is considered a noxious weed in some counties of Nebraska and in some neighboring states. Mowing will not kill the plant. Repeated mowing may be needed on moist sites. Seeds are small brown to black in color. Goats will graze Scotch thistle plants, eating flowerheads, and sheep may feed on small rosettes. Establishing a dense well-maintained pasture is effective in preventing and competing with a Scotch thistle infestation. This will avoid costly, long-term control efforts. Scotch Thistle is a Class B Weed. The Conservation Services Division provides technical and financial support, leadership and statewide coordination, and regulatory oversight to public/private landowners and agricultural businesses statewide on an array of natural resource management challenges. SCOTCH THISTLE: Options for control Flowers are globe shaped, violet to purple, 1-2 inches wide. BCS 853 VS SCOTCH THISTLE “THE MOWDOWN SHOWDOWN” feat. One of the few herbicides that provides soil residual control 1 year after application. Scotch Thistle Fact Sheet. Leaves are arranged on an alternate pattern from the stalk and can be 20 inches long. Leaves are oblong and lobed with yellow spines (Figure 3). Trials show that preventing seed set for five years reduced a large thistle population, however plant numbers returned to pre-trial levels after only two years when no control was undertaken. Weed class: B Scotch thistle is a Class B noxious weed and control is required in King County. Because it reproduces by seed, Scotch Thistle can be controlled by mechanical, chemical and cultural methods. Preventing spread. Fall treatments are better after a light freeze. Scotch Thistle Noxious Weed Control Board, Washington State. Native thistle provide important habitat and food sources for native fauna. Integrated weed management; An integrated management program is the key to successful thistle management. Thistles often invade overused or disturbed land, such as cultivated fields. Conservation Services. Be sure to select a product labeled for the site. Integrated Taxonomic Information System. It is prohibited to transport, buy, sell, offer for sale, or distribute plants or plant parts of quarantined species into or within the state of Washington or to sell, offer for sale, or distribute seed packets of seed, flower seed blends, or wildflower mixes of quarantined species into or within the state of Washington. For questions about the quarantine list, contact the Washington State Department of Agriculture's Plant Services Program at (360) 902-1874 or email PlantServices@agr.wa.gov. Acta Oecologica 24(2):77-86. Kyser et al. General. Scotch thistle Pacific Northwest Extension Publication PNW 569. Dig out rosettes by severing plant's taproot with a shovel below the soil's surface. On the far right are soldiers wearing Highland dress (of the 71st Regiment of (Highland) Foot (Fraser's)), ready to proceed with the "Scotch butchery" of Boston. bcinvasives.ca / info@bcinvasives.ca / 1-888-933-3722 • 3 » Effective management has included taproot cutting to 2.5-5.0 cm belowground, followed by a chemical control. Scouting, monitoring, and proper identification are key factors for management. Plants are usually 2-6 feet tall but can grow to a height of 12 feet with a width of 5 feet (Figure 2). [Accessed Sep 10, 2014]. Aminocyclopyrachlor provides excellent control of Scotch thistle at most growth stages. See our Written Findings for more information about Scotch thistle (Onopordum acanthium). Please see WAC 16-752 for more information on the quarantine list. Biennial; Family: Sunflower (Asteraceae) Weed Research and Information Center, University of California 2003. The addition of a non-ionic surfactant to the herbicide mix will aid in control. Schuster, M., and T.S. It may also be found alongside streams and rivers. Onopordum acanthium is classified a noxious weed in at least 14 states, with each plant capable of dispersing thousands of seeds into the wind. Healthy pasture is particularly important in the autumn, when most Scotch thistle seeds germinate. Scotch thistle weed report from the book Weed Control in Natural Areas in the Western United States. Control of Scotch Thistle starts with good grazing management and attention to disturbed areas where the plants can become established. Small infestations can be dug out. A thistle crown weevil (Trichosirocalus horridus) that feeds on musk, bull, plumeless, Italian, and creeping thistles will also feed on cotton thistle. Establishing a dense well-maintained pasture is effective in preventing and competing with a Scotch thistle infestation. Flowerheads that are cut when already in bloom may still release seed if left on the ground. Mowing can be done but will have to be repeated for the regrowth. This species is also on the Washington quarantine list (known as the prohibited plants list) and it is prohibited to transport, buy, sell, offer for sale, or to distribute plants or plant parts, seeds in packets, blends or "wildflower mixes" of this species, into or within the state of Washington. Mowing has limited effectiveness for controlling Scotch thistle, usually only prevents seed production. Animals rarely eat the plant. Re-treatment is usually necessary for three to five years or until the seed in the soil is exhausted. Prevention is the best control method for both perennial and biennial thistles. Management. Scotch thistle is generally quite susceptible to most herbicides compared with some other thistle species, though it is harder to kill as it gets larger. Scotch thistle gall fly (PDF File, 313.0 KB) Scotch thistle gall fly monitoring form (MS Word Document, 547.5 KB) Controlling thistles. Establishing and maintaining dense, vigorous, competitive pasture can effectively prevent establishment. An Integrated Pest Management plan (IPM) can be developed to manage, contain and eradicate the invasive species before it can spread further. Besides encouraging competing vegetation where possible, every effort should be made to prevent established plants from going to seed. Bidwell Canyon Farm Recommended for you Scotch Thistle. Its dense stands compete with native plants for resources and can form a physical barrier to water and grazing for animals. Speaking of the Southwest, it is considered an invasive in the Grand Canyon . Scotch thistle is a problem in rangelands and other open areas. Mowing has limited effectiveness for controlling Scotch thistle, usually only prevents seed production. Mow too early and plants can recover and flower. Scotch Thistle A weed report from the book Weed Control in Natural Areas in the Southwestern United States, 2013, DiTomaso, J.M., G.B. Some parts of this site work best with JavaScript enabled. Cut off all plant tops bearing flower heads or buds, and carefully bag and dispose of them in the garbage, do not compost. Bull thistle (Cirsium vulgare) (Figure 2) has been present in Oklahoma for more than 40 years and occurs statewide. Chemical. Management of seed production is the key to keep this plant from spreading. Water, livestock, wildlife, and humans disperse seed. The globe-shaped flowerheads solitary or in groups of 2-7 on branch tips. Plants flower in mid-summer. UNL web framework and quality assurance provided by the, Apply to the University of Nebraska–Lincoln, Give to the University of Nebraska–Lincoln, Institute of Agriculture and Natural Resources, Strengthening Nebraska's Agricultural Economy, Invasive Scotch Thistle Weed has Staying Power, Also known as: Cotton thistle, Heraldic thistle, Scotch cotton thistle. The leaf margins of a flowering bull thistle plant (a) are tipped with spines, and the stems have spiny wings. thistles also feed on bull thistle. Please refer to the PNW Weed Management Handbook, or contact your county noxious weed coordinator. It can invade healthy, undisturbed sites as well, out-competing desirable forbs and grasses in pastures and rangeland and reducing biodiversity. Vigilant II can also be used by applying it to at least 50% of the leaves of the plant, wiping the applicator along the middle of each leaf. Learn how to control Scotch Thistle. Scotch thistle will grow in wet meadows and pastures as well as dry pastures and rangelands. A chemical follow-up treatment may be needed to manage surviving plants. Several different management options will need to be utilized to manage this weed. It is not grazed by stock due to its dense spines. Search “thistle” or “invasive.”, Kadrmas, T. et al, Managing Scotch Thistle, University of Nevada, Fact Sheet 02-57, Schuster, M. and T. S. Prather, Scotch Thistle, University of Idaho, PNW 569. Picloram has also proven effective, however, it is not suitable for wet, coastal soils. Introduced into the United States as an ornamental plant in the 1800s. Isolated plants or small patches can be removed using tools such as a hoe or mattock. Early Detection and Rapid Response (EDRR) is a concept to identify potential invasive species prior to or just as the invasive is becoming established. Many insects feed on the leaves, stems, flowers and seeds, while some songbirds also feed on thistle seeds. Scotch Thistle Also Known As: woolly thistle, cotton thistle, heraldic thistle. Scotch thistle is a prolific seed producer. The majority of Scotch thistle infestations in Washington occur in eastern … Having well-established perennial grasses and forbs on a maintained pasture or rangeland with proper grazing and rotational grazing techniques can go a long way to prevent its establishment. Each thistle plant can produce up to 40,000 seeds. It also can be found in over-grazed sites, roadsides, and riparian areas. Scotch thistle continues to be grown in gardens around BC. Onopordum acanthium. Is this Weed Toxic? Plants are either male or female (dioecious). Scotch thistle reproduces by seed. This is one in a series of articles on current or potential invasive species in Nebraska by the Nebraska Extension Invasive and Resistant Pest Issue Team. It has a taproot. Small infestations should be eradicated before they spread. Spring or fall applications, especially in the rosette stage, prior to the pre-bud stage, are best. Communications Bldg.Lincoln, NE 68583-0918. 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