Flower Seed Head. Thistles are found throughout the United States and Canada. Pasture Thistle, also called Field Thistle, is a biennial or short-lived perennial. A common type of weed most homeowners and gardeners hate to see sprouting up on their turf is thistle. The next emerging leaves … Seeds. Soil disturbance can stimulate germination and a flush of new plants. What's more, one individual plant can produce up to 5,000 seeds, making it quite prolific. Bull thistle (Cirsium vulgare) is a plant that is related to the sunflower family but has none of the charm and beauty of those sunny-nodding flower heads. Biennials require portions of two growing seasons to reproduce. Seedling: Cotyledons of the bull thistle are oval-shaped, being broadest at the apex. For grassy areas, it is best to use a selective broadleaf herbicide to keep the competitive grasses intact. However, it has been shown to have limited effectiveness. Program offices are located at 201 S. Jackson St., Suite 600, Seattle, WA 98104. The bull thistle is a biennially growing plant. Bull thistle - Cirsium vulgare or Canada thistle - Cirsium arvense).As a biennial it reaches flowering stage in year 2 before dying off. 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. Melissa King began writing in 2001. After spraying, wait two weeks or more to give the herbicide time to work. Public and private landowners are not required to control infestations of bull thistle that occur on their property in King County. Bull thistle plants can produce approximately 7000 seeds. See the biological control page for more information. Wildflowers Of WisconsinWild… 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. 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. A single field thistle seed with pappus. Though bull thistle is difficult to contain, frequent mowing before it flowers can help keep it … Seeds buried at a depth of 5 inches may remain viable for up to three years. If your site has animals grazing, please read instructions carefully on grazing restrictions. 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. Seeds on the surface typically do not survive for more than a year; seeds buried may remain viable for up to three years. Nyjer seed also commonly known as niger or thistle seed is popular with many backyard bird species, particularly seed-eating birds and winter finches. In this video, I show you how to identify Bull Thistle Seeds in the Fall. Find more gardening information on Gardening Know How: Keep up to date with all that's happening in and around the garden. Contaminated hay is a primary means of spread of this species so be careful to purchase weed free hay or watch closely for new plants in the areas hay is kept or spread. As mentioned earlier, they thrive in disturbed soils.) Harvest The leaves of a bull thistle are large, woody and are flatted and basal rosette during their firs… It has a central taproot so does not spread by rhizomes. All biennial thistles considered noxious are native to Europe or Eurasia, and were introduced into North America as seed contaminants. Roots. The seeds are wind dispersed, and they’re liable to pop up in any corner of our land that gets decent sun. Bull thistle seed production is impacted by the seedhead gall fly, Urophora stylata. Clemson University. Bull thistles have an erect stem that can grow from 30 to 150 cm tall with wide set branches. To contact staff, see the Noxious Weed Control Program Directory, send an email, or call 206-477-WEED (206-477-9333). Bull thistle might be confused with native thistles as well as more serious noxious weeds such as milk thistle, a Class A noxious weed in Washington, and Canada thistle, a Class C noxious weed that is much more difficult to control. We can provide advice on how to control bull thistle, but there is generally no legal requirement to do so. The plant has the ability to produce around 5,000 seeds in a season. The seed of bull thistle remains viable for only a few years, but structures similar to those on dandelion seeds enable new bull thistles to drift downwind into the park. Seeds remain viable in the soil for up to 10 years. The flowers are produced at the ends of the tangled stem growth and last for several weeks before producing tiny striped seeds capped with white downy hairs. On smaller plants, the whole stem and branches are spiny-winged. This gall fly’s larvae induce and feed on gall tissue in the developing bull thistle seedhead, reducing seed production up to 60%. Flowers and fruit. …and without the pappus. Bull thistle starts life as a spiny leaved rosette. The roots of this plant are taproots. If the bull thistle population is large enough to support a good sized population of this insect, it can be an effective way to reduce seed production of the bull thistle. By: Bonnie L. Grant, Certified Urban Agriculturist. Around here it’s not too hard to find a thistle plant, and our main variety is common Bull Thistle (Cirsium vulgare). Weedy characteristics: Bull thistle is highly competitive and aggressive, and forms dense colonies that choke out native vegetation important to wildlife and pollinators. Mechanical control: Mowed thistles will produce new branches from basal buds but close cutting or cutting twice per season will usually prevent seed production and reduce the population over time. The seeds survive in soil for more than 10 years. As the stem gets thicker, the wings start drying and disappearing. In addition to attracting finches, it also attracts chickadees, siskins, and other small songbirds. Stems. It is a prickly biennial that grows freely in disturbed soils, pastures, ditches, roadsides and unmanaged spaces. Not only does the goldfinch pull the seeds out to eat; it also uses the thistle down (the pappus) to line its nest. Each plant has a fleshy taproot. Bull thistle (Cirsium vulgare) is a plant that is related to the sunflower family but has none of the charm and beauty of those sunny-nodding flower heads. Read about the presence and treatment of bull thistle after the 2012 Reading Fire. Seeds usu-ally germinate in the spring and fall and have a 95% germination rate. When roasted, the thistle's seeds serve as a coffee substitute. Also, goats and sheep have both been used for grazing management of bull thistle. Clemson, SC. The Bull thistle also provides seeds to granivores (consumers of grains and seeds) such as goldfinches. Urophora stylat… Seeds spread by wind and have high dispersal rates. Of course, your battle with the plant will only be as effective as your neighbors because of the travel ability of the downy seeds. Of Weed most homeowners and gardeners hate to see sprouting up on their in... 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