• Russian Knapweed Plant 215x150

Category B Weed

Sunflower family (Asteraceae)

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Russian knapweed (Acroptilon repens)


    • Numerous; highly branched, stiff, 1-3 ft. tall and covered with wooly gray hair; NO wings


      • Alternate; mostly covered with wooly gray hair

      • Lower leaves 2-4 in. long with lobed to wavy edges (margins); upper leaves strap-like (linear) or lance-shaped and less than 1.2 in. long with smooth or toothed edges


        • Purple, pink or white, each located at the tip of a branch; base of flower is vase-shaped, 0.25-0.5 in. wide and covered with green bracts with papery or whitish edges


          • Creeping root system; upper roots often dark brown to black


            • Grows well on a broad range of sites; often found in rangeland, waste areas, roadsides and along waterways; known to occur in all Nevada counties

            • Perennial; reproduces by roots and seed

            • Causes "chewing disease" in horses by damaging the area of the brain that controls fine motor movements, particularly of the mouth; results in starvation or dehydration


              • Mowing and tillage are NOT effective

              • Apply glyphosate, chlorsulfuron or clopyralid from the bud to flower stage; aminopyralid or picloram from bud through dormancy; imazapic to dormant plants in fall