Background: Russian knapweed is native to Eurasia. It infests rangelands, field edges, pasture, roadsides, and other disturbed soils. Knapweeds release chemical substances into the soil that inhibit the growth of competing vegetation. It can cause "Chewing disease" in horses that consume it.
Description: A perennial, Russian knapweed grows two to three feet tall. Roots may go eight feet deep or more. Basal leaves are lobed and are two to four inches in length. It has pinkish flowers. Flower bracts have membranous, cream-colored tips. Bloom is early summer through late summer.
Control: Biocontrol is available, but limited. Select herbicides can offer good to excellent control when applied between pre-bloom to the killing frost. Contact your local state or county weed specialist for specific updated information.