Regional Program Tackles Aggressive Knotweed

July 23, 2014

A regional program launched last year aimed at reporting and eradicating invasive knotweed species from the Comox Valley was so successful in finding and treating select knotweed locations, that this year the program has expanded to include all four local governments (Town of Comox, City of Courtenay, Village of Cumberland and the Comox Valley Regional District (CVRD).

This program is in partnership with the Coastal Invasive Species Committee (Coastal ISC) and is asking the public to report sightings of knotweed. The program aims to verify all knotweed reports within the Comox Valley and to provide professionals to conduct treatments on select sites. To report infestations or call 1-250-857-2472 by August 15, 2014.

Coastal ISC appreciates the cooperation of all residents in addressing knotweed.  Local residents in CVRD Electoral Areas A, B and C can benefit from free treatments by stem injection now until early fall, while knotweed treatments in Comox, Courtenay and Cumberland will be on public lands. Reporting knotweed is very important in all jurisdictions regardless of whether it is growing on public or private lands. By knowing where it is growing the various authorities can map the occurrences and understand the potential for spread of the plant over time.  All authorities request that residents report any sightings of the knotweed species.

Considered one of the world's worst invaders, this hollow stem shrub (which resembles bamboo), can destroy fish and wildlife habitat, penetrate pavement causing damage to infrastructure such as roads, walls and drainage systems. In the UK, Japanese knotweed has grown rampant, causing severe financial implications, including mortgages refused on properties with knotweed.

Cutting, mowing, and pulling stimulate shoot growth and may cause roots to spread further resulting in new infestations up to 20 metres away. As well knotweed has the ability to regenerate from a very small root or stem fragment and can remain dormant for many years. This is especially problematic when growing near riparian areas as the fragments can enter the waterway and regenerate further downstream.

"Knotweed is a bully in the plant world. It's an invasive and aggressive plant that spreads easily and can impact property values, the environment and cause safety issues on roadways. Look for the Knot on My Property program on our website or pick-up a booklet from any four local governments to learn more ways to defend your property from invasion” explains Rachelle McElroy, Executive Director of the Coastal ISC.

“This is a great opportunity to work with our local governments region-wide to proactively implement the treatment of knotweed species,” said Edwin Grieve, Comox Valley Regional District board chair. “As it is expensive and difficult to control once it is fully established, this is a cost-effective means to gain effective control before that happens.”

A knotweed alert sheet, providing information on identification, proper disposal, and reporting options has been developed and is available on the CVRD website

For more information on identification of this plant and its damaging impacts; as well as other invasive species that are being managed in your area please visit: and click on the "Invasive Species" tab.

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