Dyer's Woad
Isatis tinctoria

This plant is listed as a Class A noxious weed because of its impacts and widespread distribution in many western States, including Utah, Idaho, Wyoming, Montana, California and Oregon.

Dyer's woad was discovered in 1986 in Washington State, growing along railroad tracks in Kittitas County. In 1992, dyer's woad was eradicated from this site. The site is monitored continually, with no new plants found. Removing this plant from the State is a true success story in the fight against invasive species; this is one of the very few noxious weeds that have been eradicated from the State.

Dyer's woad is native to Russia, and was introduced as a crop in 18th-Century England for the extraction of a blue dye from its leaves. Dyers woad was introduced to Utah from Ireland in 1910, as a contaminant in alfalfa seed. The state of Utah has lost millions of dollars in crop damage and loss of wildlife habitat. Tens of thousands of acres in Utah, Idaho and Wyoming are infested with this perennial mustard.

Dyer's woad is sometimes found in gardens, and as a Class A noxious weed in Washington State, eradication is required. Dyer's woad is on the Washington State quarantine list (144 KB Acrobat file, 21 seconds with 56K modem), and it is illegal to buy, sell, transport or offer this plant for sale in the state.

For more information about dyer's woad, please follow this link to the WA State Noxious Weed Control Board.

If you find dyer's woad in King County, please notify us through our online infestation form.

To find out where we have records of this weed in King County, use our interactive noxious weed map and search for dyer's woad.