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Biological controls for DYERS WOAD coming soon.




The Henry’s Fork CWMA with grant support from the Idaho Department of Agriculture has been increased early detection and eradication efforts on Dyer’s Woad in Fremont County, ID during the past 3 years. Survey efforts have detected 13 locations, most associated with the Eastern Idaho Railroad, totaling less than 10 acres. Most infestations are located on private property, however some state and federal lands are being threatened. For more project information contact Craig McClure, Yellowstone National Park Exotic Plant Management Coordinator, at 307-344-2168 or Bryce Fowler, Fremont County Weed Supervisor, at 208-709-2181.



DYERS WOAD - Isatis tinctoria L.  Brassicaceae - (Mustard family)

Dyer's woad is a winter annual, biennial or short-lived perennial; 12 to 48 inches in height. Leaves of dyer's woad are alternate, simple, petiolate, bluish-green with a whitish nerve on the upper surface of the blade. The inflorescence has a flat top, petals yellow; fruit a pod, indehiscent, black or purplish brown and one-celled, containing a single seed. Dyer's woad was introduced from Europe. It made its first appearance in the United States in colonial times. It has a thick tap root which may exceed 5 feet in depth. Once leaves are removed mechanically, plants will regenerate from roots. Dyer's woad is first found along roadsides and disturbed sites and spreads from there to rangeland and cropland by seeds from late spring to mid-summer. (Courtesy of Weeds of the West). For more information on this plant go to the USDA PLANTS database.


Control Strategies:

Fremont County Weed & Pest Wyoming - A small stand of this weed was discovered in the Lander area in 2004.  Monthly throughout the growing season, we pull every plant that is found. Dyers woad is hard to manage. The deep roots make it hard to pull by hand, and it spreads quickly. Escort and Telar at 0.75 ounces per acre are equally effective in controlling this weed, but on rangeland sites there will also be a lot of damage to desirable species. Treat this weed as soon as you find it to avoid later treatment conflicts.