TANSY RAGWORT is a Noxious Weed - Send it Packing!

Fri, 01/16/2015 - 14:19 -- Victoria

The Tansy Ragwort project was a joint project of Victoria Master Gardeners Association and The Cowichan Fair in 2014.  A PDF attached below provides additional information, including website references and more photographs.

1. WHAT is Tansy Ragwort?

Tansy Ragwort (Senecio jacobaeae) is a European import. It is native to the British Isles and was likely introduced to North America as a medicinal herb. Tansy Ragwort was first recorded in BC at Nanaimo in 1950, and since then has greatly expanded its range. It is however a plant that is NOT welcome anywhere on Vancouver Island! According to BC’s Weed Control Act, Tansy Ragwort is considered a ‘noxious weed’ within ALL regions of the province (websites listed in PDF file below).

2. WHY should we get rid of Tansy Ragwort?

Tansy Ragwort is an invasive plant that can take over a farmer’s fields. This means there is less pasture for his livestock to graze on. When that field is cut, the hay or silage off it will have less nutritional value. Tansy Ragwort is also toxic and is especially deadly to horses, cattle and goats. Even if they eat just small amounts of the plants, green or dried in hay, the effects of the poisoning are cumulative and will result in damage to the animals’ livers.

3. WHAT does Tansy Ragwort look like?

Tansy Ragwort, pictured above, is a biennial with a low-growing rosette of dark green ruffled leaves in its first year. Small daisy-like flowers appear on tall stalks in its second year. Those masses of bright yellow blooms are easy to spot in heavily-infested fields or along highways. If you stop for a closer look, its ruffled or ragged leaves are a quick way to identify Tansy Ragwort.

4. WHAT is this weed’s natural enemy?

The Cinnabar Moth (Tyria jacobaeae) is a biological control for Tansy Ragwort. Easy to recognize because of the unique red and dusky black pattern on its wings, this daytime-flying moth is definitely one insect that you want to see flitting about the weed patch. The moth’s eggs hatch into boldly striped caterpillars. They feed on the Tansy Ragwort flowers and leaves, crawling from one plant to another after the first has been defoliated.

5. WHAT do you call Tansy Ragwort?

Most plants, both good and bad, are known locally by a common name. One of Tansy Ragwort’s nicknames is ‘Stinking Willy’. What do you know it as? St. John’s Wort (Hypericum perforatum) and Common Tansy (Tanacetum vulgare) are often mistakenly identified as Tansy Ragwort. These two weeds also have yellow flowers and are in bloom during the summer.

6. HOW can we ‘send it packing’?

Tansy Ragwort is a weed nobody wants to see in their backyard or growing on the property next door, so it’s important to encourage everyone to dig it up or pull it out at all stages of its life cycle. If it’s already going to seed (some time in late August/early September), pull the plant and bag the blooms. Handle them carefully to avoid scattering the dandelion-like fluff further. Dispose of both in the garbage; don’t put them in your compost.

7. WHAT else can we do?

Although it is best to eliminate this noxious weed by digging it out, a task that’s easier to do when the soil is moist, Tansy Ragwort can be kept in check if it is mowed regularly. Be aware that while this does prevent the plant from producing flowers and seeds in its second year, Tansy Ragwort remains a problem because it can now become a short-lived perennial. Consult a professional if you plan on using chemicals to combat a major weed infestation.

8. WHERE can you find more information?

Type Tansy Ragwort into Google to bring up a number of online sites. Since we live on Vancouver Island, a good one to start with is ‘Coastal Invasive Species Committee’ or Coastal ISC. Its address is http://www.coastalisc.com/ You can also search websites for other communities in the Pacific Northwest (i.e. Whatcom County, Washington) to learn how they are tackling the problem of Tansy Ragwort in their neighbourhoods.


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