Spotted knapweed (Centaurea biebersteinii)

  • Spotted Knapweed Plant 215x150

Category A Weed

Sunflower family (Asteraceae)

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    • Up to 4 ft. tall, rough-textured, branched and bushy; NO wings on upper stems


      • Alternate, gray-green, up to 8 in. long; most are pinnate-divided, dotted with resin and sometimes covered with small grayish hairs; upper leaves smaller and narrower with few to no lobes


        • White to purple, each located at the tip of a branch; base of flower is vase-shaped, 0.5 in. long, 0.3-0.5 in. wide and covered with bracts with dark, comb-like tips that give the appearance of spots (after which the weed is named)


          • Deep, stout taproot


            • Grows best on dry, well-drained soils; often infests rangelands, waste areas and roadsides; known to occur in Carson City, Clark, Douglas, Elko, Eureka, Humboldt, Lander, Lyon, Lincoln, Nye, Washoe and White Pine counties

            • Biennial; reproduces by seed and lateral roots


              • Mowing plants in bud to flower stage can reduce seed production; repeated hand removal can be effective; DO NOT burn
              • Several insect biological control agents are available Apply 2,4-D or dicamba in the rosette stage; apply clopyralid, picloram or aminopyralid between rosette and mid-bolt stages 


                Spotted Knapweed Infestation 215x150
                Spotted Knapweed Plant 215x150 Spotted Knapweed Flower 215x150
                Spotted Knapweed Leaves Stem 215x150
                Leaves on stem
                Spotted Knapweed Rosette 215x150
                Nevada Noxious Weed Field Guide
                Nevada Noxious Weed Guide