Description:
Dyers woad grows as a winter annual, biennial or short-lived perennial, ranging from 1 to 4 feet tall, from a 3-5 foot long taproot. The basal rosette produces stalked, bluish-green leaves covered with a fine hair. The rosette leaves range from 1 1⁄2 to 7" long, and they are succulent. All leaves have a cream colored mid-rib from tip to base. When the rosette bolts, up to 20 stems can be produced. Usually 7-8 of these stems mature, producing many somewhat woody, flowering branches.

• Mechanical: Hand pulling is the recommended control option - after the plant bolts, and before seed production. This is considered the only practical control method of hard to reach, or difficult terrain.
• Biological: The native rust pathogen Puccinia thlaspeos is effective in preventing seed or fruit production. The rust seems to be spreading naturally to new dyers woad populations, and it is controlling further spread (James et al. 1991). Sheep will not voluntarily graze the plant.
• Herbicide: Herbicide control is more effective before the plant bolts. For site specific control information, please refer to the annually updated Pacific Northwest Weed Control Handbook. Metsulfuron in combination with 2,4-D are most effective in pastures and rangelands (Evans and Gunnell, as cited in McConnell et al. 1998). Refer to the State Noxious Weed Control Board site

For More Information:
Detailed information about Dyers Woad is available at the Washington State Noxious Weed Control Board Web Site.