Dyer's Woad. Image from utahweed.org. (click to enlarge)

Stop the Dyer's Woad: Pull. Cut. Report. Repeat.
23 May 2026

It looks innocent enough — a cheerful little plant with bright yellow flowers, nodding in the spring breeze. Don't be fooled. Dyer's woad (Isatis tinctoria) is one of the most aggressive invasive weeds in Weber County, it is officially classified as a noxious weed under Utah law, and right now it is blooming in Ogden Valley.

Know Your Enemy
Dyer's woad was brought to North America centuries ago to make blue dye. It has repaid that favor by spreading aggressively across rangelands, roadsides, and open fields ever since. Here's what makes it so dangerous: each plant can produce up to 10,000 seeds. Let one patch go to seed and you've just planted next year's army.

Spot it now by its bright yellow flower clusters, flat dark teardrop-shaped seed pods, blue-green leaves that clasp the stem, and dense patches glowing along roadsides and disturbed ground. If a hillside looks suspiciously cheerful and yellow right now — that's the enemy.

What To Do
The window is open. Act now, while it's flowering but before those seed pods drop.

Pull it out by the roots — the whole root, gloves recommended. Cut it at the base if pulling isn't possible. Bag it and trash it — do not compost it. Those seeds will survive and return for revenge.

See a big patch? Grab some neighbors and garbage bags and go to war. Woad-pulling parties are a thing, and there is something deeply satisfying about ripping an invasive weed out of the ground by the root.

Another option includes Weber County Weed Control.  They are available to spray weeds, including Dyer’s Woad, for residents at the residents’ cost.  Contact Bart Cragun at (801) 399-8356 or go to this website:  https://www.webercountyutah.gov/weeds/

Report It
Spot a significant infestation on public land or a neighbor's property? Weber County can assist with large patches and has authority to require landowners to deal with noxious weeds. To report, go to Weber County Weed Control (webercountyutah.gov/weeds/) and select “Report a Weed” on the left-hand menu.