Stem

  • Stiff, wiry, 1-6 ft. tall and usually branched; wings less than 0.2 in. wide extend down stem
Photo of yellow starthistle leaves

Leaves

  • Blue- to gray-green, 1.5-6 in. long and densely covered with fine hairs
  • Rosette leaves are oval to strap-like (linear) with deeply lobed edges (margins); stem leaves are alternate, strap-like to oblong with smooth to wavy edges
Photo of yellow starthistle flower

Flower

  • Yellow, located singly at branch tips or axils; base of flower is vase-shaped, 0.5-0.75 in. diameter and covered with cotton-like hairs and stout, straw-colored spines 0.5-1 in. long
Photo of yellow starthistle plant

Root

  • Deep taproot
 

Other

  • Infests rangeland, pastures, croplands, waste areas and roadsides; known to occur in Carson City, Douglas, Elko, Humboldt, Lander, Lyon, Storey, Washoe, and White Pine counties
  • Annual; reproduces by seed
  • Causes “chewing disease” in horses by damaging the area of the brain that controls fine motor movements, particularly of the mouth, resulting in starvation or dehydration 
 

Control

  • Grazing, mowing, burning, pulling, digging and cultivation can be effective if done prior to seed production
  • Several biological control agents are available 
  • Apply 2,4-D, dicamba, or triclopyr rosette to bolt; glyphosate bolt to flowering; aminocyclopyrachlor, aminopyralid, clopyralid or picloram preemergence to rosette; chlorsulfuron preemergence
Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B. 2020, Yellow starthistle, Extension, University of Nevada, Reno, Field Guide

Learn more about the author(s)

Heidi Kratsch
Heidi Kratsch
 

Also of Interest: