Stem

2-6 ft. tall and sometimes wooly and branched; spiny wings caused by leaf bases that extend down the stem

Photo of musk thistle plant with pink flowers

Leaves

Dark green with a light-green midvein, 4-15 in. long, alternate and sometimes hairy; edges (margins) are deeply lobed and spiny

Flower

Pink to purple (occasionally white), up to 3 in. wide, each located at the tip of a stem; head often nods or droops; stem below head usually spineless
Base of flower is covered with green, purple- or straw-colored, spine-tipped bracts; bracts are 0.1-0.3 in. wide, lance-shaped and sometimes hairy

Root

Deep, fleshy taproot

Photo of musk thistle plants with pink flowers

Other

Often infests roadsides, pastures and waste areas; known to occur throughout Nevada
Biennial; reproduces by seed; also known as nodding thistle

Control

Mowing, tilling or hand removal after bolting but prior to flowering is effective; remove the top 2 in. of crown by digging before seed production
Several biological controls are available
Apply 2,4-D, chlorsulfuron, clopyralid, dicamba, glyphosate, picloram, or triclopyr to young actively growing plants; aminopyralid, imazapic, imazapyr, metsulfuron, or sulfometuron preemergence or post emergence on young plants

Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B. 2020, Nevada Noxious Weed Field Guide – Musk thistle, Extension, University of Nevada, Reno, Field Guide

Learn more about the author(s)

Heidi Kratsch

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Nevada Noxious Weed Field Guide – Yellow starthistle Yellow starthistle is a noxious weed that has been identified by the state of Nevada to be harmful to agriculture, the general public, or the environment. Learn more about this weed. Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B. 2020, Extension, University of Nevada, Reno, Field Guide

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Nevada Noxious Weed Field Guide – Musk thistle