Noxious Weed Information and Control

  • Diffuse Knapweed (Centaurea diffusa)
  • Spotted Knapweed (Centaurea maculosa)
  • Dalmatian Toadflax (Linaria dalmatica)
  • Hound's-Tongue (Cynoglossum officinale)
  • Leafy Spurge (Euphorbia esula)
  • Poison Hemlock (Conium maculatum)
  • Poison ivy (Rhus radicans)

Weeds tend to sprout up first where people travel the most; roads, trails, railways, fields and water ways. Across some of our landscapes, noxious weed mono-cultures are replacing our native plant populations and reducing or eliminating bio-diversity. They reduce forage for wildlife and livestock and reduce habitat for other animals.

Noxious weeds are typically non-native plants that have been introduced to British Columbia without the insect predators and plant pathogens that help keep them in check in their native habitats. They are legislated under the B.C. Weed Control Act and possess some or all of the following characteristics which allow them to be invasive and difficult to control:

  • Aggressive, prolific seed producers
  • Produce seeds which can lie dormant for decades
  • Have extensive root systems, thorns or burrs for protection
  • Produce chemicals which inhibit growth of surrounding vegetation

Noxious weeds are a problem but if everyone does even a small part in prevention and control of the invasion, progress can be made. As with most things, prevention is preferable to the cure. Doing nothing is a choice which has consequences - the following are some positive things that we can all do:

  • Learn to recognize these plants (see photos and links)
  • Avoid weed patches where possible, stay on established roads and trails
  • Clean clothes, boots, bikes, vehicles and pets after encountering weeds
  • Report noxious weed locations to the land owner or to the Regional District
  • Control noxious weeds on your own private property. IIf only a few plants are found pull them out.
    • If not flowering, you can leave them to compost where they are
    • if flowering, bag seed heads for disposal. Congratulations you have just reduced the seed bank.

Please share your knowledge with friends, family co-workers and anyone else you meet in your travels. A few of the main problem weeds that can be found along the Trans Canada Trail include:

  • Diffuse Knapweed: biennial to short-lived heavily branched taprooted perennial grows 0.6 to 1 metre in height. divided leaves greyish-green in colour, hairy; very bitter to the taste white, occasionally purple flowers; bracts of the flower heads with small, sharp, rigid spines one of 13 "knapweed" species in British Columbia For more information and picture: http://www.agf.gov.bc.ca/cropprot/weedguid/diffknap.htm
  • Spotted Knapweed: biennial to short-lived taprooted perennial with branched stems growing 1.5 metres in height. deeply cut hairy leaves; very bitter to taste. purple, occasionally white flowers; flowerhead bracts with black-tipped fringe giving head a "spotted" appearance For more information and picture: http://www.agf.gov.bc.ca/cropprot/weedguid/spotknap.htm
  • Dalmation Toadflax: creeping rooted perennial to 1.2 metres tall; pale green waxy leaves clasp the stem and are heart-shaped with a pointed tip. bright yellow "snapdragon-like" flowers with orange spot on the lower lip (2.5 to 4 cm long) likely introduced to North America as an ornamental. For more information and picture: http://www.agf.gov.bc.ca/cropprot/weedguid/dalmtoad.htm
  • Hound’s Tongue: biennial taprooted weed growing 0.5 to 1.2 metres tall;. soft, hairy rosette leaves produced in first year resemble the shape of a dog's tongue. dull reddish-purple flowers bear 4 rounded triangular seeds covered with hooked prickles easily spread by seed attachment to clothing and animals contains toxic alkaloids that can cause liver damage in grazing animals well adapted to forested areas, roadsides and meadows For more information and picture: http://www.agf.gov.bc.ca/cropprot/weedguid/houndst.htm
  • Leafy Spurge: perennial with persistent vertical and horizontal creeping roots. grows to 0.8 metres tall; leaves spirally arranged on the stem. inconspicuous greenish-yellow flowers inserted above 2 leaf-like yellow-green bracts all parts of the plant contain a white milky latex that can irritate skin of livestock and humans. For more information and pictures: http://www.agf.gov.bc.ca/cropprot/weedguid/leafysp.htm
  • Poison Hemlock: also known as poison parsley or spotted parsley, is an erect biennial weed that can grow 6 to 10 feet tall. Originally imported from Europe as an ornamental plant, its spread across the North America has been rampant. All parts of this plant are poisonous. For more information and pictures: http://www.al.gov.bc.ca/weedsbc/weed_desc/poison_hem.html
  • Poison Ivy: contains a poisonous sap that can cause swollen, red, itchy skin along with broken and oozing blisters, all of which can appear anywhere from six hours to two weeks after exposure. Identified by three glossy, oval leaflets, two lateral and one in the center. Leaf color changes with the season; poison ivy leaves are green in the summer but change to shades of yellow, orange, and red in the fall and spring. The hairless poison ivy leaves range from three-fourths of an inch to four inches long. Poison ivy grows on woody stems, often climbing on nearby vegetation. Note, this is not an invasive species.

More information about noxious weeds:

Information supplied by: Anne Skinner, Range Agrologist Cranbrook Forest District