• Yellow Starthistle Plant 215x150

Category A Weed

Sunflower family (Asteraceae)

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Yellow starthistle (Centaurea solsitialis)


    • Stiff, wiry, 1-6 ft. tall and usually branched; wings (less than 0.2 in. wide) extend down stem


      • 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


        • 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


          • Deep taproot


            • Often infests rangeland, pastures, cultivated fields, waste areas and roadsides; known to occur in Carson City, Churchill, Douglas, Elko, Humboldt, Lander, Lyon, Mineral, Pershing, Storey and Washoe 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


              • Grazing, mowing, burning, pulling, digging and cultivation can be effective if done prior to seed production

              • Several biological control agents are available

              • Apply aminopyralid, 2,4-D, clopyralid, dicamba or picloram to actively growing plants before flowering