Stem
- Up to 4 ft. tall, rough-textured, branched and bushy; NO wings on upper stems
Leaves
- Alternate, gray-green, up to 8 in. long; most are pinnate-divided, dotted with resin and sometimes covered with small grayish hairs; upper leaves smaller and narrower with few to no lobes
Flower
- White to purple, each located at the tip of a branch; base of flower is vase-shaped, 0.5 in. long, 0.3-0.5 in. wide and covered with bracts with dark, comb-like tips that give the appearance of spots (after which the weed is named)
Other
- Grows best on dry, well-drained soils; often infests rangelands, waste areas and roadsides; known to occur throughout Nevada
- Biennial; reproduces by seed and lateral roots
Control
- Mowing plants in bud to flower stage can reduce seed production; repeated hand removal can be effective; DO NOT burn
- Several insect biological control agents are available
- Apply 2,4-D or glyphosate rosette to bolt stage; aminocyclopyrachlor, aminopyralid, clopyralid, or picloram preemergence to bolt stage
Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B.
2020,
Nevada Noxious Weed Field Guide – Spotted knapweed,
Extension, University of Nevada, Reno, Field Guide