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

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 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

Learn more about the author(s)

Heidi Kratsch

Also of Interest:

Nevada Noxious Weed Field Guide – Russian knapweed