Tansy Ragwort

Invasive Species:

Common Tansy (Tanacetum vulgare): Perennial species that reproduces by seed and can grow up to 1.8 m in height. Common Tansy has many yellow, disc-shaped flowers that are found at the top of the plant in flat-topped clusters.

Common Tansy prefers to grow in sunny areas with well-drained soils and cannot establish in frequently tilled soils.

 

 

 

 

St. John’s Wort (Hypericum perforatum): Perennial that grows to about 1 m in height. St. John’s Wort has showy, bright yellow flowers with 5 petals that turn rusty red when they mature. It prefers dry, sandy soils and grows in full sun.

Tansy Ragwort was introduced to North America in the 1900’s and was brought over from Europe and spread in contaminated hay. It is most often found in disturbed sites and on bare ground in grazed pastures, roadsides, vacant non-crop lands and on forest clear-cuts.

Tansy Ragwort thrives in full sun or partial shade with well-drained soil. It is not commonly found in areas with high water tables or acidic soil.

• Tansy Ragwort spreads primarily by seeds, as they get carried off by the prevailing winds. Seeds may also be spread by people, water, animals, and livestock. Tansy Ragwort seeds are also transported in soil being carried by equipment or vehicles. This species’ seeds can remain viable for up to 15 years depending on their depth.
• Tilling, grazing or other disturbances will cause dormant seeds to germinate. Plants that go to seed will die at the end of the season.
• Regeneration of shoots can also occur from crown buds, root fragments and intact roots. As with the seeds, disturbance or injury to shoots promotes vegetative propagation.

Tansy Ragwort is found in the Sea to Sky region, but with a limited distribution. The goal is to eradicate this species from the region, and to prevent new introductions.

Learn to identify Tansy Ragwort: use the images on this page to learn how to identify Tansy Ragwort.

What to do if you spot it: You can report any Tansy Ragwort sighting by visiting our reporting page..

 

DO:

• Regularly monitor properties for weed infestations.
• Ensure soil and gravel is uncontaminated before transport
• Quickly re-vegetate disturbed areas with fast-growing competitive, native plants can limit growth of Tansy Ragwort and is a fundamental tool to limit it.
• Minimize soil disturbance in area surrounding infestation
• Ensure plants (particularly flowering heads or root fragments) are bagged or covered to prevent spread during transport to designated disposal sites (e.g. landfill).

DO NOT:

• Plant Tansy Ragwort in a garden, no matter how well-contained its enclosure may seem.
• Move soil that has been contaminated with Tansy Ragwort.
• Unload, park, or store equipment or vehicles in infested areas; remove plant material from any equipment, vehicles, or clothing used in such areas and wash equipment and vehicles at designated cleaning sites before leaving infested areas.

Control

Mechanical Control

Only effective on established stems if the root system is entirely removed or frequently cultivated (tilled), which prevents the growth of seedlings and root sprouts. Repeated heavy cultivation can be used as a control technique and frequent mowing before flowering can prevent seed production. Hand pulling is only effective in small infestations and if root is completely removed.

Chemical Control

The use of a wick or selective spot spraying is recommended to minimize non-target damage. Effective herbicides include dicamba, 2,4-D, picloram, and picloram + 2,4-D. Spring or mid-summer applications of 2,4-D are most effective at managing young seedlings and rosettes, while dicamba/dicamba + 2,4-D are more effective on advanced growth stages.

Note that picloram is not suitable for wet coastal soils.

We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial and federal laws and regulations; species-specific treatment recommendations, and site-specific goals and objectives.

Biocontrol

Defoliating moths (Tyriah jacobaeae), root feeding beetles (Longitarsis flavicorni, L. jacobaeae), and seed head flies (Hylemya seneciella) have been effective in biologically controlling Tansy Ragwort in places such as the Fraser Valley.