Weeds: Bull thistle – Cirsium vulgare

• Family: Asteraceae (Compositae)
• Cycle: Biennial
• Plant type: Broadleaf

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

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

• 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.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

• 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.

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