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
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

Learn more about the author(s)

 

Also of Interest:

 
Photo of diffuse knapweed with white and pink flowers
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
Russian Knapweed Control Trial 2013-2015, Pershing County
A document of effective ways to maintain and control Russian Knapweed crops.
Foster, S., and Schultz, B. 2016, Extension, University of Nevada, Reno, PS-16-04
Paradise Valley Weed Control Demonstration Plot: Russian Knapweed
Russian knapweed is a long-lived perennial broadleaf forb. New populations typically establish from seedlings. Long-term, its spread is largely from the lateral expansion of an extensive creeping root system. Individual plants reproduce vegetatively (i.e., are clonal) and become ...
Schultz, B. 2005, University of Nevada Cooperative Extension
Managing Spotted Knapweed
Spotted knapweed is an invasive, noxious weed that should be prevented from invading lands in Nevada. It can be successfully managed over time using a variety of integrated measures if addressed in an aggressive, consistent manner using the best knowledge about control methods av...
Graham, J. and Johnson, W. 2004, University of Nevada Cooperative Extension
Photo of squarrose knapweed plant with small pink flowers
Nevada Noxious Weed Field Guide – Squarrose knapweed
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
 

Associated Programs

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Integrated Pest Management

Integrated Pest Management program is a long-term management strategy that uses a combination of tactics to reduce pests to tolerable levels with potentially lower costs for the pest manager and minimal effect on the environment.

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Master Gardeners of Washoe County

Master Gardeners provide free, research-based horticulture information to Nevadans.

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Master Gardeners of Nevada

Program trains local gardeners to provide research-based horticulture information to Nevadans