Description:
Common crupina is an erect winter annual, 1 to 3 feet tall. Cotyledons are large, thick, shiny and dark green, with a prominent mid-rib that may be purple to red. The species overwinters as a rosette. Plants have alternate leaves that are finely divided into lace-like leaflets (pinnatifid or bipinnatifid). Both the leaves and stem have short stiff spines. Flowers are lavender to purple and grow in 1⁄2-inch long heads. Each plant can have as many as 40 flowering heads; individual heads produce 1 to 5 seeds. Flowers partially protrude through a whorl of bracts. Seeds (achenes) are 1/8 to 1⁄4 inch long, and are cylindrical, tapering to a blunt end. The seed coat is covered with tiny hairs, giving the seeds a black to silvery beige appearance. The apical end of the seed has dark, stiff, barbed hairs (pappus) (Thill et al. 1987).

• Mechanical: Since common crupina is an annual plant, hand-pulling or hoeing can be effective. However, these tactics require many visits to find all plants (Zamora et al. 1989b).
• Biological: Several natural enemies have been identified on common crupina in southern France and are under investigation as possible biological control agents (Sobhian et al. 1996). No biocontrols are currently approved for use in the United States.
• Herbicide: Belles et al. (1981) obtained effective control of common crupina with glyphosate, dicamba, and picloram. Treatment timing is important. Residual herbicides should be applied no earlier than June to compensate for emergence of plants in late June (Zamora and Thill 1989). For specific herbicide recommendations, consult the Pacific Northwest Weed Control Handbook.Refer to the State Noxious Weed Control Board site

For More Information:
Detailed information about Common Crupina is available at the Washington State Noxious Weed Control Board Web Site.