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Tansy ragwort

Tansy ragwort

Tansy ragwort

(Senecio jacobaea)

Priority: -  Control

Tags: Agricultural | Medicinal | Toxic

Overview

Identification

Ragged looking plant up to 1 metre tall. Plants have one to several upright stems that are branched near the top.

During the first year tansy ragwort forms a rosette with dark green, ruffled (lobed) leaves on purple stems. Leaves on second year plants are alternate, dark green on top, whitish-green underneath, with deeply cut, blunt-toothed lobes and a ragged, ruffled appearance.

Flowers are bright, yellow, and daisy-like arranged in a dense, flat-topped cluster near the top of the stem.

Reproduction

Biennial or short-lived perennial. Reproduces mostly from seed, but will reproduce vegetatively (from root and stem fragments) if disturbed (i.e., mowed or hand pulled). Seeds can be viable up to 15 years depending on depth in the soil. Tilling, grazing, or other disturbance will cause dormant seeds to germinate. Plants that go to seed die at the end of the season.

Habitat & Ecology

Found on disturbed sites and bare ground in grazed pastures, roadsides, vacant non-crop lands, and on forest clear-cuts.

Impacts

Reduces forage available for grazing, contaminates crops; poisonous to livestock and wildlife.

Management

Hand pulling can be effective in small infestations where followed up with re-treatment. Entire root mass must be removed if this method is used. Repeated mowing before flowering can be done to prevent seed production however be aware that vegetative reproduction is stimulated by mowing, grazing, or poor hand removal if the entire root mass is not removed. If plants are hand pulled or cut prior to flowering the plant material may be left on site to decompose. If after flowering, all plant parts including flower heads should be bagged and incinerated or buried deeply at a landfill.

Tansy ragwort is under biocontrol in BC: a defoliating moth (Tyria jacobaeae), seedhead fly (Hylemya seneciella also known as Botanophila seneciella), root feeding beetles (Longitarsis flavicorni, Longitarsis jacobaeae), and root crown feeding moth (Cochylis atricapitana) have been effective in controlling tansy ragwort in many areas of the Fraser Valley.