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

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
Photo of musk thistle rosette
 

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
Photo of musk thistle pink flower
 

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

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