Stem
- Up to 2 ft. tall; rough-textured; highly branched; bushy; covered with short, stiff hairs; NO wings on upper stems
Leaves
- Alternate, lower leaves pinnate-divided, 4-8 in. long; sometimes covered with short grayish hairs; upper leaves strap-like (linear) with smooth edges (margins)
Flower
- White to pale purple, located at the tip of a branch; base of flower is vase-shaped, 0.5 in. long, 0.12 in. wide and covered with yellow, comb-like bracts tipped with a narrow spine
Other
- Grows best in dry, well-drained soils; often infests rangelands, waste areas and roadsides; known to occur in Douglas, Elko, Eureka, Lander, Lincoln, Nye, Washoe and White Pine counties
- Biennial, but sometimes annual or perennial; reproduces by seed; dry, mature plants often break off and tumble in the wind to spread seed
Control
- Mowing plants in bud to flower stage can reduce seed production; repeated hand removal can be effective; burning is NOT effective
- Several insect biological control agents are available
- Apply 2,4-D or dicamba in the rosette stage; apply aminocyclopyrachlor, aminopyralid, chlorsulfuron, clopyralid, imazapyr or picloram pre-emergence to rosette and mid-bolt stages
Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B.
2020,
Nevada Noxious Weed Field Guide – Diffuse knapweed,
Extension, University of Nevada, Reno, Field Guide
