- Control Strategies
- Infestation Map
BULL THISTLE - Cirsium vulgare (Savi) Tenore
Asteraceae - (Sunflower family)
Bull thistle is a biennial with a short, fleshy taproot. The stem is 2 to 5 feet tall, bearing many spreading branches. It is green or brownish, sparsely hairy, irregularly and spiny winged. Leaves in the first year form a rosette, stem leaves are pinnately lobed, hairy and prickly on upper side and cottony underneath. Flowers are 1 1/2 to 2 inches wide, more or less clustered at the ends of branches. Involucral bracts are narrow, spine-tipped, progressively longer and narrower from outer to inner ones, flowers dark purple. Seeds are topped by a circle of plume-like white hairs.
Bull thistle is a native of
Eurasia and is now widely established in North America, having been
introduced many times as a seed contaminant. Pastures, roadsides and
disturbed sites are potential habitats for this highly competitive
weed. Flowering occurs from July through September. It is possible
to separate bull thistle from Canada thistle by examination of the
leaves alone. Bull thistle leaves are prickly hairy above and
cottony below, while Canada thistle leaves are glabrous above and
glabrous or hairy below.
(Courtesy of Weeds of the West)
Bull thistle is easy to control in the rosette stage with 2,4-D, Tordon, Transline, Curtail, Clarity, or Milestone. This weed is an indicator of over grazing or other surface disturbance and responds well to changes in management designed to promote perennial ground cover.
NOTE: All Pesticide application recommendations are based on label directions and experience with these products in Fremont County Wyoming. However, labels change from time to time. Ultimately it is the responsibility of the applicator to insure the pesticide application is made within the directions on the current product label. If you are unsure of, or have questions concerning treatment method or a chemical usage please consult your local Weed & Pest office, or a licensed professional.