Contractor Ernie Sellentin works to eradicate an investation of invasive knotweed.

Greenways, city team to tackle knotty issue

Invasive plant crew works this month to repel knotweed invasion from sensitive ecological areas

A white hazmat suit is not typical landscaping attire, but it’s needed when dealing with one of the World’s Top 100 Most Invasive Plants. In July, Campbell River will host a Vancouver Island Invasive Plant crew that will treat dozens of knotweed infestations in environmentally sensitive areas on public lands.

“The only known effective treatment is injection of each stem with herbicide” said contractor Ernie Sellentin. “It’s labour intensive, and requires a multi-year investment, but it’s the only technique that works.”

Sandra Milligan, Greenways Land Trust Director who works on Invasive Plant Projects, is happy to report that partnership with the City has resulted in knotweed eradication from some areas. However, many other infestations still threaten salmon habitat. “Knotweed outcompetes native plants, removes food and nesting resources, causes bank erosion and siltation that reduces salmon habitat, and creates a fire hazard.”

Greenways Operations Manager Cynthia Bendickson notes that “knotweed has caused significant devaluation of real estate and natural ecosystems in other communities. Education of the public is very important so that we can find and treat small infestations to reduce the overall economic impact of this dangerous plant.”

Pat English, Manager of Economic Development for the Mount Waddington Regional District, has a $150,000 proposed program for knotweed treatments. English considers this a “protective disbursement” expense that reduces the risk of knotweed getting into sewers and storm drains and damaging infrastructure; Port Hardy roads have already experienced pavement damage.

“Implementation of the City’s Invasive Species Policy includes a commitment to protect our natural areas from infestations like these,” said Terri Martin, Environmental Coordinator for the City of Campbell River. “Knotweed also creates road visibility problems and can damage infrastructure. Collaboration with Greenways Land Trust allows the City to meet its goals.”

The City program is focused on environmentally sensitive areas and public lands, but many knotweed infestations are found only on private land. The B.C. Weed Act “imposes a duty on all land occupiers to control designated noxious plants” and it includes all knotweed species.

What can you do if you have knotweed on your property?


• Call Greenways Land Trust at 287-3785 to report the location. Infestations near creeks are given priority on the treatment list

• Hire a professional to treat the infestation. You can call Jason at Strategic Forest Management 250 287-2246, ext. 126 for an estimate.

• Treat any plant material as hazardous waste: dispose of only in the regular garbage, NOT with yard waste and not at the City’s Yard Waste Drop-off Centre. If you mow it, clippings can create new infestations; bag them. Cut off the flowers before they go to seed to reduce the potential for new infestations.

• Knotweed reproduces using underground rhizomes. Treat any soil with root fragments as hazardous waste: a piece the size of a fingernail can produce a 10 foot plant.


Milligan acknowledges that knotweed can be very frustrating to land owners who have had their yards taken over by it.

“It takes years of work to remove an infestation,” she said. “We very much appreciate efforts to ensure the plant is contained. We don’t want the plant to spread, but we do want the word to spread.”