A tough weed to kill, the flower heads on thistles possess thousands upon thousands of thistle seeds, which allows them to spread at an exponential rate both above and below the soil. The white pappus “parachute”or “hair”, is about ¾ inch long (20+ mm). Weedy characteristics: Bull thistle is highly competitive and aggressive, and forms dense colonies that choke out native vegetation important to wildlife and pollinators. By: Bonnie L. Grant, Certified Urban Agriculturist. Bull thistle is a Class C Noxious Weed in Washington, first listed in 1988. The seeds survive in soil for more than 10 years. It's no wonder this species might take over a pasture in a few short years. The second true leaf is dark green and covered densely with white hairs on the upper surface. Cirsium silvaticum Tausch. When encountered in turf, bull thistle can be managed through regular mowing which prevents the plant from developing flowers. It has a central taproot so does not spread by rhizomes. Seeds germinate rapidly and are spread by wind. Digging the plant out with a spade or hori hori is the best approach to mechanical bull thistle control. Musk thistle and bull thistle are biennials causing major problems in perennial grass crops including pastures, roadsides, conservation reserve and fence rows. Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins, mostly in the family Asteraceae.Prickles can also occur all over the plant – on the stem and on the flat parts of the leaves. Bull thistle control can be manual or chemical with an emphasis on seed co… Other Info: Similar to Canadian thistle, the more robust bull thistle was introduced to the United States in the 1800’s from Europe and Asia, and has now spread to 42 states, being declared a noxious weed in 16. For this reason, bull thistle removal is a priority among farmers and meticulous gardeners. Thistle seed bird food is great for year-round feeding. Bull thistle - Cirsium vulgare or Canada thistle - Cirsium arvense).As a biennial it reaches flowering stage in year 2 before dying off. Caution: Plants have spines along leaves and stems. After hatching, the larvae burrow into the seed-prodcuing tissues to feed, forming galls and reducing seed production. 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Chemical control: For information on herbicides and recommendations for control, please see the Pacific Northwest Weed Management Handbook. All biennial thistles considered noxious are native to Europe or Eurasia, and were introduced into North America as seed contaminants. The bull thistle is a biennially growing plant. Do not leave cut stems of flowering bull thistle on the ground because they are likely to form viable seed after they are cut. The species name, altissimum, means “the tallest.”It is a biennial with a tap root, not a rhizomatous root like some agressive, non-native thistles (i.e. Around here it’s not too hard to find a thistle plant, and our main variety is common Bull Thistle (Cirsium vulgare). The seeds are wind dispersed, and they’re liable to pop up in any corner of our land that gets decent sun. In addition to attracting finches, it also attracts chickadees, siskins, and other small songbirds. Casual removal with this method is likely to leave behind the genesis of a plant in spite of the foliar amputation. Knowing which birds eat Nyjer can help birders choose the best birdseed and appropriate feeders for their backyard flock. Each plant has a fleshy taproot. …and without the pappus. Prevention: Bull thistle only reproduces by seed so prevention of seeding and takign care not to spread seeds are key to preventing new infestations. Seeds remain viable in the soil for up to 10 years. This thistle plant I’m testing is a bull thistle, and the spines are huge and rigid. Seeds usu-ally germinate in the spring and fall and have a 95% germination rate. Most seeds germinate rapidly, usually in the spring and fall. Sign up for our newsletter. The Bull thistle was used by early humans as a warm medicinal tea. What is bull thistle? The types of sprays used in agricultural scenarios are dicamba, glyphosate or 2,4D. Become a certified small business contractor or supplier, Find certified small business contractors and suppliers, Washington State Noxious Weed Control Board, Pacific Northwest Weed Management Handbook, King County bull thistle best management practices, University of Washington Burke Museum Herbarium Image Collection - Cirsium vulgare, Branching, erect biennial, 2 to 6 feet tall, Rosettes form in first year, flowering stems the second, Long, sharp spines on the leaves at the midrib and the tips of the lobes, Leaves are deeply lobed and hairy - there are coarse hairs on leaf tops, making leaf feel rough to the touch, and woolly hairs on the underside, Leaf bases extend down onto stems and form spiny wings along the stems, Flower heads are "gumdrop" shaped and spines extend all around the base of the flower heads. It is a free-seeding weed with a prickly demeanor and rapid spread. Bull thistle spreads by seeds. Clemson, SC. Roots. Bull thistle plants can produce approximately 7000 seeds. The flowers are located at the end of stems covered in spiny hairs. Bull thistle is a biennial plant that can grow up to six feet tall. Bull thistle grows in disturbed areas such as pastures, roadsides and ditches. Harvest Cirsium vulgare, the spear thistle, bull thistle, or common thistle, is a species of the Asteraceae genus Cirsium, native throughout most of Europe (north to 66°N, locally 68°N), Western Asia (east to the Yenisei Valley), and northwestern Africa ( Atlas Mountains ). Additionally, native thistles are noticeably less prickly than weedy, non-native thistles, like bull thistle (Cirsium vulgare) or Canada thistle (Cirsium arvense). In order to reduce the seed population, cut off the seed head and tuck it into a sack to keep the fluffy seeds from dispersing. Bull thistles are biennial and only bloom every two years. Mowing can be effective, but make sure the plants do not flower. Clemson University. Cutting off only the flower stalks will merely make the plant sprout another shoot; also, cut flower stalks left on the ground are likely to produce viable seeds, even after they are cut. The outer rim of the flower is green and spiny itself, and contains many disk shaped flowers that are reddish-purple. It has a deep taproot, which makes manual pulling a challenge. The roots of this plant are taproots. The plant has the ability to produce around 5,000 seeds in a season. There are several herbicides that are effective on bull thistle, but it is important to carefully match the product with your site, local conditions and regulations, and other weed and land management issues, and always follow the label directions for the product you are using. Prevention: Bull thistle only reproduces by seed so prevention of seeding and takign care not to spread seeds are key to preventing new infestations. 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