WSU Extension

Hortsense

Weeds : Bull thistle : Cirsium vulgare
(revision date: 8/13/2015)

Family: Asteraceae (Compositae)
Cycle: Biennial
Plant Type: Broadleaf

Use Integrated Pest Management (IPM) for successful weed management.

Biology
A first-year plant of bull thistle is a rosette of deeply lobed, wavy-margined leaves. The upper surface of the leaves is prickly and hairy, while the underside is cottony. Mature second-year plants may reach up to five feet tall and almost as wide. Leaves are alternate on the branching, irregular, spiny, winged stems. The dark pink to purple flowers are one to two inches wide, appearing singly in mid-summer on the ends of branches. The flower bases are covered with spines. Bull thistle spreads only by seeds (unlike Canada thistle, Cirsium arvense, a similar plant that is an aggressively spreading perennial). SPECIAL INFORMATION: Bull thistle is designated as a Class 'C' noxious weed in WASHINGTON and a Class 'B' noxious weed in OREGON. Management may be required by law in your county. In addition, it is on the Oregon noxious weed quarantine list, which prohibits sale, purchase, and transport of plants, seeds, and plant parts. Consult your local Noxious Weed Control Board for more information.
Habitat
Bull thistle is commonly found in pastures, fields, waste areas, and roadsides on fairly rich, moist soils.

Management Options

Non-Chemical Management
  • Cultivation (rototilling or hoeing) will effectively eliminate plants.
  • Careful digging is useful to manage weed populations. However, digging can carry undesirable weed seed to the surface and foster further germination.
Select non-chemical management options as your first choice!

Chemical Management

Apply according to label directions. Glyphosate products should be applied as spot treatments only. NOTE: Some ingredients listed here are only available in combination. Read the label carefully on combination products to make sure the product is suitable for your specific situation.

Landscape areas
  • glyphosate
  • dichlobenil
Turf areas
  • products containing 2,4-D
  • triclopyr
  • 2,4-D + MCPP + dicamba
Bare ground areas
  • glyphosate
  • products containing 2,4-D
  • triclopyr
Images
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Caption: Bull thistle flower
Photo by: J.A. Kropf
Caption: Bull thistle leaf tips, spined
Photo by: J.A. Kropf
Caption: Bull thistle flower stem
Photo by: D.G. Swan
Caption: Thistles (Canada on left, Bull on right)
Photo by: T. W. Miller
Caption: Bull thistle bud
Photo by: T. W. Miller
Caption: Bull thistle leaf
Photo by: T. W. Miller
Caption: Bull thistle rosette
Photo by: T. W. Miller