BACKGROUND: Originally found in Eurasia, spotted knapweed infests rangeland, pastures, roadsides, or any disturbed soils. Knapweed’s release chemical substances into the soil that inhibit the growth of competing vegetation.
DESCRIPTION: Spotted knapweed is a short-lived perennial one to three feet tall. The rosette leaves are deeply lobed and may be six inches in length. The stems are moderately leaved. Flowers are typically pink with spots on the flower bracts. Bloom is in early summer.
CONTROL: Several biocontrol agents are available and offer fair to good control. Select herbicides can offer good to excellent control when applied between rosette and pre-bud stages. Contact your local state or county weed specialist for specific updated information.
Photos and text taken from Noxious Weed Field Guide for Utah
