Description:
Musk thistle is a biennial plant although it may occasionally act as a winter annual. It is a robust thistle and given the right conditions may grow to six or seven feet tall. The large solitary flowers heads at the ends of the stem are reddish purple. The flower heads droop at maturity. Each plant may have 50 to 100 flower heads with up to 1,000 seeds per head. The seeds do not have a plume or parachute. The stems are spiny and winged except just below the flower head. The deeply lobed, spiny leaves are alternate on the stem.

• Mechanical: Musk thistle may be handpulled or grubbed out. Properly managed pasture will resist musk thistle infestations as long as adjacent infestations are controlled. In cropland situations cultivation will kill young seedlings.
• Biological: A seed eating weevil, Rhinocyllus conicus is quite effective in reducing seed output.
• Herbicide: 2,4-D, dicamba, clopyralid, and picloram effectively control musk thistle (See Pacific Northwest Weed Control Handbook). 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 Musk Thistle is available at the Washington State Noxious Weed Control Board Web Site.