Description:
Description and Variation: Purple starthistle is an erect, branched, annual or biennial plant. The stems and leaves are covered with cobwebby hairs often becoming smooth with maturity. The lower leaves are deeply divided and the upper leaves are narrow and undivided. The rosette leaves are deeply divided with a circle of spines in the center. The flower is lavender to deep purple with spine-tipped bracts subtending the flower head.

• Mechanical: Grubbing or digging can be effective for small infestations of purple starthistle. Mowing is not effective.
• Biological: No biological control program is currently being developed for purple starthistle. Reportedly, biotypes of Bangasternus, a seed head weevil, utilize purple starthistle in Europe.
• Herbicide: Herbicides are most effective when applied in the spring to the sensitive rosette stage. Glyphosate, 2,4-D, dicamba, and picloram are reportedly effective. Read and follow current herbicide labels and recommendations for control. Refer to the State Noxious Weed Control Board site

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