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

Stem

Up to 12 ft. tall and branched, with spiny wings along smooth stem; covered with wooly, gray hairs

Leaves

Alternate; oblong, 4-20 in. long, covered with wooly, gray hairs giving plant a gray-green appearance; edges (margins) are lobed or toothed with stiff spines

Flower

White to purple flowers, each located at the tip of a branch; base of flower is round and resembles a squashed globe, 1-2 in. wide and covered with green, purple or yellow bracts less than 0.2 in. long, each tipped with a spine; often covered with wooly, gray hairs

Root

Fleshy taproot

Other

Often infests pastures, rangeland, roadsides and waste areas; known to occur throughout Nevada
Biennial; reproduces by seed
Forms dense stands that are difficult for humans and animals to penetrate

Control

Hand-removal, digging or mowing prior to flowering can be effective
Apply 2,4-D, chlorsulfuron, dicamba, metsulfuron or picloram to actively growing rosettes; aminopyralid, chlorsulfuron, clopyralid or dicamba+2,4-D between rosette and late-bolt stage; aminocyclopyrachlor pre- and post emergence

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

Nevada Noxious Weed Field Guide – Scotch thistle