Tansy ragwort is highly toxic and causes significant economic damage through livestock poisoning and contamination of milk, honey, and herbal remedies. It is listed as a Class B noxious weed in Jefferson County, meaning it is required for control. Acting early is the most efficient way to prevent any weed from spreading.

Life-cycle (Biannual)

In its first year Tansy ragwort produces a rosette, followed by 1-2 stalks growing up to 4 feet with a yellow flower cluster during the second year.

Each plant can produce up to 200,000 seeds per year that are dispersed by wind, water, animals, clothing, and machinery. Seeds can remain viable and germinate in the soil for up to 15 years.

Why be concerned?

All parts of Tansy ragwort contain highly toxic alkaloids that attack the liver when ingested. Signs of poisoning can take up to 6 months before becoming apparent, but poisoning damage is irreversible and deadly.

Although unpalatable to livestock, it is eaten unintentionally when in rosettes grow in forage areas or if it is present in hay crops. It can be toxic to humans through contaminated milk, honey, or herbal remedies.

Control

• Always avoid direct contact with the plant, wear protective gear like gloves.

• Hand pulling or digging, removing the entire taproot to prevent re-sprout, is a very effective method.

• Cutting & bagging flowers and seed-heads, and disposing of them at the land-fill will prevent seed dispersal temporarily until the plant re-flowers.

• Bio-controls (insects) can be used for long term management and can be available through the WSU Extension. However, flowers and seed heads still need to be removed initially.

• Chemical controls can be effective for large infestations if applied correctly.

• Mowing is not recommended because it can make the plant become persistent as a perennial until it completes its cycle and goes to seed.

Prevention

• Re-seed bare ground with desirable plants to prevent noxious weeds from taking advantage.

• Clean equipment and gear to prevent transporting seeds.

• Use weed free hay and soil to avoid bringing in new infestations.

• Monitor your land and remove small infestations before they take hold.

• Contact us for advice on any infestations you see.

If you see Tansy Ragwort or have any questions regarding it or any other noxious weeds,

please contact Joost Besijn, the newly appointed Jefferson County Noxious Weed Board Coordinator.

Joost Besijn, Coordinator, Jefferson County Noxious Weed Control Board Phone: (360) 379-5610 Ext 205 Email: noxiousweeds@co.jefferson.wa.us