05/27/2026
W**d Watch Wednesday – Tansy ragwort (Senecio Jacobaea)
Tansy ragwort is very invasive, especially in overgrazed pasture settings, and is very TOXIC. It can be lethal to horses and livestock both in pasture and dried in hay, causing irreversible liver damage. The toxic properties are also a threat to humans, as milk from livestock or honey from bees can become contaminated by animals and insects that utilize tansy ragwort plants. Tansy ragwort is a Class B-designated w**d in Clallam County, meaning controlling infestations and preventing the spread of all propagules is required.
Tansy ragwort is a biennial plant. It spends its first year of life as a rosette with ruffled dark green leaves making it harder to identify since it doesn’t flower at this stage of life. During the second year it becomes much more obvious, sending up one or more stems with bright yellow flowers that stand one to four feet tall at maturity. It typically begins blooming in late June, and will often bloom all summer long through the early fall.
Pulling is a very effective means of control, however wear gloves if doing so as it is also reported to be phototoxic and can cause skin irritation or burns if skin that has had contact with sap is exposed to the sun. Herbicide treatment is also an option, but make sure to read and follow all herbicide label information.
For more information, please visit WA State Noxious W**d Control Board’s website: https://www.nwcb.wa.gov/w**ds/tansy-ragwort. If you see this plant or would like control recommendations, please contact the Clallam County Noxious W**d Control Board at 360-417-2442 or email web_w**[email protected].
For assistance with pasture management techniques to help control tansy ragwort and other pasture w**ds, please contact Clallam Conservation District or visit our website: https://www.clallamcd.org/farm-assistance
Photos courtesy of Washington State Noxious W**d Control Board website.
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