Silage with Russian knapweed is unpalatable. For these reasons, Russian knapweed is a prohibited species under the Canada Seed Act. Canadian infestations are limited to the southern prairies, south-central British Columbia, and southern Ontario. Once established, Russian knapweed out-competes other herbaceous plants on most soils including those that are saline and impacted. It occurs in irrigated and arid areas, but is most common in the drier regions of Canada where it is a particular problem in irrigated alfalfa.
Russian knapweed regenerates readily after cultivation.
Glyphosate with cultivation and cropping will suppress the weed. Picloram is the preferred treatment for spot control in grassland. As seed is not a major concern in Canada, the best biocontrol agents may be gall-formers that redirect the plant's food reserves, or root feeders . The root moth Stenodes nomadanais is reported to kill plants it attacks In Canada, the plant is almost free of enemies except for a rust disease, Puccinia acroptili , which was probably introduced with it. The rust is widely established, but with a few exceptions does little damage.