County’s program steps in when people need a helping hand to battle tansy ragwort

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Tansy ragwort blooms in a pasture stall near Enumclaw, King County.

It’s the first week of August, the days are hot, and there’s one plant on every Noxious Weed Specialist’s mind: tansy ragwort (Senecio jacobaea). This biennial, regulated Class B noxious weed grows throughout King County, especially on open, sunny sites such as in pastures and on roadsides. Tansy ragwort is an especially big worry in part because it’s toxic—even fatal—to cattle, horses, goats, pets, and people. It spreads entirely by seed, and right now is crunch time to catch mature tansy ragwort plants before they disperse.

In general, landowners are responsible for controlling all the tansy ragwort (and any other regulated noxious weed) on their property under the state noxious weed law. Noxious Weed Specialists are mostly there to help them identify the weeds and provide tips on how to get rid of them. However, in certain cases, for reasons such as physical, financial or other significant challenges, a landowner isn’t able to control the regulated weed on their own. In these instances, the King County Noxious Weed Control Program steps in to help as part of the county’s Equity and Social Justice (ESJ) Initiative.

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In its first year, tansy ragwort forms a basal rosette with ruffled leaves.
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Second-year plants produce 2-4-foot-tall, leafy, flowering stalks.
Stem leaves are dark green above, whitish-green below, with deeply cut, blunt-toothed lobes.
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From June-October, mature plants produce clusters of daisy-like flowers with 13 yellow ray petals and a yellow-orange center. Each plant can produce up to 150,000 seeds, which spread by wind, mowing, or animals.

On August 2nd, I traveled with Weed Specialists Daniel Sorensen and Mattia Boscolo to the Enumclaw area for a day of tansy ragwort surveying and control. We visited sites with a wide variety of landowners. Many residents in the area had already controlled their tansy ragwort this year (thank you!). Others hadn’t realized they had the noxious weed, and were ready and able to get rid of it on their own. We also visited two sites where Daniel Sorensen, the primary Weed Specialist for the Enumclaw area, had been in contact with the landowners and knew that they—for reasons relating to Equity and Social Justice—couldn’t control the tansy ragwort themselves this year. At those properties, the three of us hopped out, grabbed our gloves, clippers, shovels, and bags, and started to pull.

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Weed Specialist Daniel Sorensen pulls tansy ragwort from an ESJ landowner’s pasture near Enumclaw, King County.


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Weed Specialists Mattia Boscolo (left) and Daniel Sorensen (right) remove tansy ragwort from an ESJ landowner’s field in the Enumclaw area.


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Tansy ragwort flower heads removed from an ESJ landowner’s property near Enumclaw.

For more information on tansy ragwort identification and control, visit the following pages:

If you’re unable to control a regulated weed on your property for reasons you believe are related to Equity and Social Justice, or if you have any other questions, please feel free to contact our program at 206-477-WEED (206-477-9333) or