Dyer's woad (Isatis tinctoria)


Category A Weed

Mustard family (Brassicaceae)

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Stem

  • Up to 4 ft. tall; branched at top; dry plants with attached seed pods remain standing into winter

Leaves

  • Lance-shaped, 1-7 in. long, bluish-green and lack hair (glabrous) with a distinct whitish midvein; edges (margins) are wavy to smooth

  • Stem leaves are alternate with lobed base that clasps the stem

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

Root

  • Deep taproot

Other

  • Grows well on a broad range of sites; often infests waste areas, roadsides, rangeland, pastures and crop fields; known to occur in Elko, Washoe 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, metsulfuron, chlorsulfuron or imazapic to young, actively growing plants

Images

Dyer's woad mature plant
Mature Plant
Dyer's woad Rosette
Rosette
Dyer's woad Infestation
Infestation
Dyer's woad Leaves and stem
Seed Pod
  Nevada Noxious Weed Field Guide
Nevada Noxious Weed Guide