Tansy RagwortKeep an eye out for that Ragwort villain posted on 07/31/2017
There’s a killer loose on the Mountain. His name is Ragwort.
That’s Tansy Ragwort to you, pal.
The invasive weed tansy ragwort has a long and deadly
history in the Pacific Northwest. It is believed to have been brought here in
the early 20th Century through ballast water from ships.
This noxious plant is dangerous to humans and livestock due
to a poisonous alkaloid in its tissue which causes liver damage when ingested,
according to Lisa Kilders, education and outreach program manager for the
Clackamas Soil and Water Conservation District.
“Horses and cows are especially susceptible to this
poisonous weed with death occurring after consuming 3 to 8 percent of body
weight,” Kilders wrote in a press release to The Mountain Times. “Humans can
also be harmed from tansy ragwort by consuming the plant, consuming livestock
suffering from liver damage … by consuming animal products such as milk (made
from liver damaged cows), and honey (made with tansy ragwort nectar).”
Ragwort is an especially familiar sight in rural
communities. It prefers a cool, wet climate, well-drained soils and full to
“You can see patches of tansy in pastures, fields,
grasslands, vacant land, waste places, horse trails, roadsides, rangeland,
riparian areas, and clear cuts,” Kilders wrote.
Tansy ragwort is a biennial, taking two years to complete
its lifecycle. In its first year, it appears as a ground-hugging rosette,
transitioning in its second year up to six feet in height. It blooms in late
spring and early summer with yellow flowers. The stems are green, sometimes
with a reddish tinge, and the leaves are dark green and ruffled.
Rosettes should be dug up, removing the root. Because it is toxic,
wear gloves and protective clothing. Pulled plants should be bagged and placed
in the municipal waste.
Mowing is not a good control method. While it may prevent
the plant from immediately producing seeds, it also stimulates additional
Insects have been introduced – most notably the Cinnabar
moth – to help control the invader. The caterpillars of the moth feed on the
flowering ragwort during the summer.
For information on how to control the tansy ragwort with chemical
controls, contact the WeedWise program at 503-210-6000.
By Larry Berteau/MT