Guest Column by Janet Stein

It is the time of year—actually a little early, thanks to our warm weather—when roadsides and pastures glow with golden flowers on long stalks. Before admiring, however, take a good look to be sure the flower is not tansy ragwort, a poisonous invasive plant that affects horses, cows, pigs, goats, deer and, yes, humans.

Tansy ragwort (Senecio jacobaea) is a noxious invasive weed that originated in Eurasia but seems to like the Pacific Northwest a lot.

Alkaloids in tansy ragwort accumulate in the liver, so even small quantities ingested by grazing animals or from contaminated hay can cause serious illness, including intestinal bleeding and death. It spoils the taste of milk and honey produced by animals or insects consuming it.

The sap can trigger inflammation on exposed skin—even the smoke of burned tansy ragwort can injure skin and lungs. This is a plant that is bad for both agricultural and recreational economies in Island County.

The Washington State Weed Control Board has designated it a Class B weed, requiring control by property owners. However, given its toxicity and readiness to spread, all citizens should recognize tansy ragwort and help to control it.

How to recognize: First-year tansy ragwort appears as a lacey rosette of leaves close to the ground. In its second year, the plant produces a stalk with deeply cut curly leaves topped with a cluster of small golden, daisy-like flowers.

Common tansy (Tanacetum vulgare) has similar leaves and is sometimes mistaken for tansy ragwort, but its flowers are yellow buttons, like a daisy without petals.

What is being done:  Mowing of roadsides does not control the weeds and can even spread them. In 2014 the Island County Noxious Weed Board collaborated with the Department of Public Works (PW) to fund a team from the Washington Conservation Corps to help with control efforts; in four days they removed over a ton of tansy ragwort, almost 9,000 plants.

Unfortunately, those funds are not available this year. Conscientious property owners and concerned individuals watch for and destroy weeds but many people remain unaware or unconcerned, even as the plants encroach on their property. It is frustrating to try to manage the weeds and see so many blooming freely.

What you can do: Notify the Noxious Weed Control Board if you see an infestation that does not appear to be addressed, especially if livestock are grazing there.

Control the weeds on your property. Manual control, pulling or digging to remove the entire root, is not very difficult with tansy ragwort and works well to control small quantities. Wear gloves, long pants and sleeves, get the plants before they go to seed and place pulled plants in strong garbage bags. Do not compost or leave beside the road. Place sealed bags in the garbage or take to one of the Island County Transfer stations which will dispose of noxious weeds at no charge.

Mechanical controls, such as tilling, can help control larger infestations but may also encourage more seeds to germinate. Tansy ragwort seeds remain viable for up to 10 years, so tilling once won’t solve the problem. Also, if the heads are removed but plants remain in the ground they will re-bloom.

Herbicides can be used on large areas, as well, with care to follow instructions on application. Consult the county’s Noxious Weed Board for an evaluation and recommendations. Call 360-678-7992 or email j.stein@co.island.wa.us for information or to volunteer for a tansy ragwort pull.

Janet Stein is the noxious weed program coordinator for Island County.