Weed(s) of the Week: Common Tansy

Common Tansy is a class B weed native to Asia and Europe. This invasive weed is toxic to humans and livestock. This is an aromatic perennial with rhizomes, reaching 1 to 5 feet tall, with fern-like foliage and yellow button-like flowers. Common Tansy is generally found along roadsides, waste areas, stream banks and in pastures. This weed reproduces by numerous tufted seeds dispersed by wind and water. Wear gloves when handling the plants. Individual plants and small infestations can be hand pulled or dug up. Mow or cut infestations before flowering and seed sets occur to eliminate seed production. Mowing alone will not kill plants so multiple treatments will be required to exhaust the plant’s resources.

Tansy Ragwort is a class B weed native to Northern Africa, Asia and Europe. This weed is toxic to humans and livestock. All plant parts are toxic, with the highest number of alkaloids in flowers, then leaves, roots and stems. Toxic properties are a possible threat to humans through food chain contaminants. Flowerheads are in somewhat flat-topped clusters, yellow in color overall, and having a daisy-like appearance. Tansy Ragwort is found in open, disturbed areas such as roadsides, pastures, fields and cleared forested areas.

Both noxious weeds are on the Washington State Department of Agriculture’s quarantine list. It is prohibited to transport, buy, sell, or distribute plants or plant parts of quarantined species into or within the state of Washington.

If you have questions about Common Tansy or Tansy Ragwort or any other noxious weeds and their identification and control, we can help. Please contact Andy Lea at 360-795-3852.