BACKGROUND: Native to Eurasia, diffuse knapweed inhabits dry rangeland, roadsides, field edges, and waste areas. Knapweed’s release chemical substances into the soil that inhibit the growth of competing vegetation.
DESCRIPTION: It is an annual or a short-lived perennial averaging one to two feet tall. Leaves have finely divided lobes. Flowers are white to rose in color. Diffuse knapweed differs from squarrose knapweed in that toothed flower bracts are straight rather than arched outward. It blooms throughout summer.
CONTROL: Several biocontrol agents are available and provide fair to good control. Select herbicides can offer good to excellent control when applied from rosette to pre-bud stages. Tillage offers good control. Contact your local state or county weed specialist for specific updated information.
Photos and text taken from Noxious Weed Field Guide for Utah
