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Weed of the Week: Common Tansy

Native to Eurasia, common tansy (Tanacetum vulgare) made its way to Canada and British Columbia in the 1600s as an alleged cure for joint pain, and for its uses as a companion plant to cucumbers, squash, and roses. It was known to repel garden pests like ants, cucumber beetles, Japanese beetles, and squash bugs. It was also used in early embalming practices.

Despite these uses, common tansy is an invasive plant in BC that displaces native vegetation, and infestations may be toxic to grazing livestock if digested in large quantities.

Invasive plants grow rapidly and spread quickly, causing damage to the environment, economy and our health; they are the second greatest threat to biodiversity after habitat loss.

Common tansy is currently distributed in the following areas of BC: Bulkley Nechako, Central Kootenay, Columbia-Shuswap, East Kootenay, and North Okanagan Regional Districts, and within Greater Vancouver, Fraser Valley, southeast coast of Vancouver Island, Gulf Islands, Sunshine Coast, and Squamish/Pemberton.

Common tansy plants grow up to 1.8 metres in height, with clusters of dense, yellow button-like flowers that occur at the tops of the stems.

This invasive plant is a perennial species that prefers sunny areas with well-drained soils. It infests stream banks, pastures, and other disturbed sites such as roadsides. It reproduces by seeds that can remain viable in the soil for up to 25 years! These seeds can be transported quickly to new areas by birds, animals, and on vehicles that have been working in infested areas.

Because of its long medicinal and horticultural use, common tansy is still available in plant nurseries and from herbal remedy suppliers. Gardeners should avoid purchasing common tansy.

You can keep this plant at bay in your garden with frequent tilling. This will deplete the food energy stored in its roots. The most effective control method combines mowing or hand cutting with chemical control, and encouraging competition from native vegetation.

Invasive plants vary greatly in western Canada's diverse climates. To find out more about invasive plants in your area or to seek alternative plants, visit www.bcinvasives.ca or phone 1-888-WEEDSBC or (250) 305-1003.

References:

http://www.bcinvasives.ca/resources/outreach-materials/invasive-plants-tips
http://www.invasiveplants.ab.ca/Downloads/FS-CommonTansy.pdf http://en.wikipedia.org/wiki/Tansy http://www.agf.gov.bc.ca/cropprot/weedguid/commtan.htm http://www.agf.gov.bc.ca/weedsbc/weed_desc/com_tansy.html

In Your Words...

  • “I am impressed with the coverage of the GIS mapping data now available. I will be developing an Invasive Species Management Plan for Pacific Spirit over the next several years and these maps will help as a coarse indication of current conditions, and in guiding initial inventory and monitoring efforts.”

    Markus Merkens, Pacific Spirit Park area manager, Metro Vancouver

  • “Working with the Hot Spots crew in Saanich in 2010, we practiced different methods to treat knotweed with glyphosate using the injection gun on several sites. With these skills I was able to implement Saanich's first knotweed eradication pesticide treatment program for private properties.”

    Donna Wong, Environmental Stewardship Officer, District of Saanich

  • "We had a great hike at Kenna Cartwright Park. The kids built a snowman and we all enjoyed the views. The outreach worker showed us some plants that don't belong in the park, gave us info about them and what to do about them, and gave us all some cool gifts from the Invasive Plant Council. Thank you!"

    Susan Hammond, Kamloops Young Naturalist Club

  • “Parks Canada and Canadians have benefited from the partnership to have on-the-ground Hot Spots crews, and we would be happy to work with a crew in the future at one of our many national parks and national historic sites that are in need of invasive plant management.”

    Brian Reader, Species at Risk Manager, Parks Canada

  • “Our crew has finished their work at Fort Rodd Hill National Historic Site and Gulf Islands National Park Reserve. I want to thank you, on behalf of Parks Canada, for providing the crew to us. They were well-trained and got a lot of important restoration work done in our nationally-important heritage areas.”

    Brian Reader, Species at Risk Manager, Parks Canada

  • “Thank you for orchestrating access to the Hot Spots crew for GINPR.  This crew allowed us to move the restoration project on Princess Margaret ahead by months if not by years.”

    Wayne Bourque, Superintendent of Gulf Islands National Park Reserve, Parks Canada

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