Tansy ragwort alarms islanders

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Salt Spring farmers and people who keep tabs on invasive species are becoming concerned about the aggressive spread of tansy ragwort, a flower classified as a noxious weed in British Columbia that has appeared all over the island this year.

The Invasive Species Council of B.C. reports the yellow daisy-like flower is a problem plant in the lower Fraser Valley, southern Vancouver Island and the Okanagan. Jean Wilkinson, who chairs the Salt Spring Conservancy’s stewardship committee, said tansy ragwort has recently become more noticeable on the island.

“These hot dry summers seem to be ideal conditions for it,” Wilkinson said.

According to the Invasive Species Council of B.C., tansy ragwort can be identified by the small daisy-like yellow flowers that appear from July to September in a flat-topped cluster. The biennial to short-lived perennial plant is found on disturbed sites and bare ground in grazed pastures, roadsides, vacant non-crop lands and on forest clear-cuts. It is often confused with common tansy, which is not poisonous. Common tansy does not have ray flowers, and has sharply toothed leaves.

With tansy ragwort, a “low rosette is produced during the first year with dark green, ruffled (lobed) leaves on purplish stems. Leaves on second year flowering stems are alternate, dark green on top, whitish-green underneath, with deeply cut, blunt-toothed lobes and a ragged, ruffled appearance.”

The infestation can spread rapidly as just one plant can produce 150,000 seeds, which spread on the wind like dandelions. Seeds can lie dormant for four to five years, or up to 20 years if buried.

The Coastal Invasive Plant Species Committee has a Weed Hotline through which residents can report weeds or ask questions at 250-871-5117, toll-free 1-844-298-2532, or email info@coastalisc.com. Reports should include a detailed description, location, contact information and photos if possible.

For more on this story, see the August 8, 2018 issue of the Gulf Islands Driftwood newspaper, or subscribe online.

 

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