Russian knapweed (Acroptilon repens)



  • Russian Knapweed Plant 215x150

Category B Weed

Sunflower family (Asteraceae)

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Stem

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

    Leaves

    • 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

      Flower

      • 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

        Root

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

          Other

          • 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

            Control

            • 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

              Images

              Russian Knapweed Investation 215x150
              Infestation
              Russian Knapweed Plant 215x150
              Mature Plant
              Russian Knapweed Flower 215x150
              Flowers
              Russian Knapweed Rosette 215x150
              Rosette
                Nevada Noxious Weed Field Guide
              Nevada Noxious Weed Guide