CIPC - Priority Invasive Plants

There are a number of invasive plant species in Coastal BC.
Download our most recent priority list here (PDF - 38KB)

Japanese and Giant Knotweed

Japanese knotweed (Polygonum cuspidatum) and giant knotweed (P. sachalinese) are tall shrubs with bamboo-like stems. They have been planted throughout South and Central Vancouver Island and the Gulf Islands as garden ornamentals but they quickly spread to form dense thickets in a variety of habitats, including dry roadsides and moist stream banks. Small patches can quickly spread into large areas, leaving little room for native species to grow.

Concern over knotweed has been mounting around the world as more and more native habitat is being lost, particularly in riparian areas. Knotweed is listed as a noxious weed in many parts of North America and should not be planted or cultivated, see:
http://www.cabi-bioscience.org/html/japanese_knotweed_alliance.htm

These plants can be identified by their tall (>3 metres), bamboo-like stem structure and extremely large heart-shaped leaves (Giant knotweed) or smaller leaves that are flat at the base with a pointed tip (Japanese knotweed). Both plants have small white flowers that bloom in late summer.

As a resident, you can help control the spread of these invasive species by removing them from your property. Small plants can be dug up, taking care to remove all plant parts to prevent re-growth. While large patches can be cut down and covered with thick plastic to prevent re-sprouting of the roots. Care should be taken in the removal and transport of plant parts to ensure that they are not spread to new areas where they may become established. Research is currently underway to determine the efficacy of controlling knotweed by injecting the stem with herbicide or over-watering plants with salt water. For more information on control methods, see: http://tncweeds.ucdavis.edu/moredocs/polspp01.pdf#search=%22knotweed%20stem%20injection%2C%20the%20land%20conservancy%22

Additional Information:
www.agf.gov.bc.ca/cropprot/weedguid ...

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