Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B. 2020, Nevada Noxious Weed Field Guide – Dyer's woad, Extension, University of Nevada, Reno, Field Guide

Stem

  • Up to 4 ft. tall; branched at top; dry plants with attached seed pods remain standing into winter
Photo of dyer's woad
Dyer's woad flowering plant

Leaves

  • Lance-shaped, 1-7 in. long, bluish-green and lack hair (glabrous) with a distinct whitish mid-vein; edges (margins) are wavy to smooth, stem leaves are alternate with lobed base that clasps the stem 
Photo of dyer's woad rosette
Dyer's woad rosette

Flower

  • Yellow with 4 petals; occur in clusters that give plant a flat-topped appearance
  • Mature seed pods dark brown to black, oblong, flattened and suspended from a small stalk; each contains a single seed 
Photo of dyer's woad plant
 

Root

  • Deep taproot
Photo of dyer's woad next to a river.
 

Other

  • Grows well on a broad range of sites; often infests waste areas, roadsides, rangeland, pastures and crop fields; known to occur in Elko, Humboldt and White Pine counties
  • Biennial, but sometimes annual or perennial; reproduces by seed
  • Historically cultivated for use as a blue dye and as a medicine 
 

Control

  • Mow in early-flower to reduce seed production; spring tillage or digging individual plants prior to seed production can be effective
  • Apply 2,4-D to young, actively growing plants; apply aminocyclopyrachor, chlorsulfuron, imazapic or metsulfuronon pre- and post emergence

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Also of Interest:

 
Photo of a field of dyer's woad next to a river.
Nevada Noxious Weed Field Guide – Dyer's woad
Dyer's woad is a noxious weed that has been identified by the state of Nevada to be harmful to agriculture, the general public, or the environment. Learn more about this weed.
Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B. 2020, Extension, University of Nevada, Reno, Field Guide