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

Stem

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

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
Photo of Russian knapweed

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
Photo of Russian knapweed

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

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Also of Interest:

 
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Nevada Noxious Weed Field Guide – Diffuse knapweed
Diffuse knapweed 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
Paradise Valley Weed Control Demonstration Plot: Russian Knapweed
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Squarrose knapweed 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’s Priority Agricultural Weeds: Russian Knapweed
Russian knapweed (Acroptilon repens) is a non-native perennial forb (wild flower) that arrived in the United States in the late 1890s. This weed is well adapted, growing in damp to poorly drained soils with high salinity and/or alkalinity.
B. Schultz, S. Foster 2021, Extension, University of Nevada, Reno, SP-21-02