District of Mount Waddington is planning the launch of a knotweed weed control program in the Coal Harbour/Quatsino area.
The Regional District is committing $5,000 per year to control knotweed, and related invasive species, in those areas with the expectation of more funding being contributed from the project’s partners the Ministry of Transportation and Infrastructure and the Invasive Species Committee.
The Regional District is also investigating whether the control program can assist workers displaced by the current curtailment of operations at the mill in Port Alice.
“Coal Harbour is one of the worst (areas) we have,” said Manager of Operations Patrick Donaghy at the Regional District Board meeting March 17.
However, he said the weed is by no means restricted to those areas.
“There’s definitely a fair bit of it in Port Hardy, around Port McNeill and close to the mill in Port Alice,” Donaghy said.
Knotweed is a plant that is hard to pull, or cut down, because “if you don’t get it right it will spread.”
Knotweed spreads rapidly through root systems that may extend from a parent plant up to 20 metres laterally and up to a depth of three metres.
Even a small fragment can propagate and if it is mowed down, parts of it may be scattered and start new plants.
The most effective and efficient way to eradicate it is through the application of a herbicide, which can be done either by injection or spray.
“One of the big challenges that you face is the public’s natural concern about the use of herbicide,” Donaghy said, and its impact on things like insects, particularly bees.
Donaghy said they will look at each site and consider the appropriate course of action for that area by using integrated pest management techniques. The overall intent is to use non-chemical means where appropriate (riparian areas) and selective stem-injections in the majority of the treatment areas. Some spraying may be required to treat small and emergent plants, but will be limited. In either herbicide application, timing and stem or flower head removal/disposal will be conducted prior to herbicide application to minimize risks to insects.
Knotweed are an invasive perennial, with four species found in British Columbia: Japanese knotweed; Bohemian knotweed; Giant knotweed; and Himalayan knotweed.
Bohemian are the most prevalent in this area, Donaghy said.
Bohemian knotweed are particularly concerning because they reproduce sexually by cross-pollination, and can adapt to their conditions.
“There’s a real concern that if we don’t get on to it, it will adapt quicker and will become more of a challenge to control let alone eradicate,” he said.
Knotweed are “very, very aggressive plants” that “basically push out most other life,” said Donaghy.
“They take no prisoners,” he said.
The plants can also be destructive to municipal infrastructure, building foundations and wells.
The RDMW is in the early stages of developing a knotweed strategy that will involve the entire North Island working together. The proposed plan will be brought before the community of Coal Harbour’s Local Community Commission and the Quatsino Band Council board in April for approval.
Knotweed have small white-green flowers that grow in showy, plume-like, branched clusters along the stem and leaf joints. Knotweed thrive in roadside ditches, low-lying areas, irrigation canals, and other water drainage systems.
They are also found in riparian areas, along stream banks, and in other areas with high soil moisture.
Knotweed are dispersed by human activities or by water to downstream areas, and are of particular concern in riparian areas and areas prone to seasonal high water or flooding.
Plants emerge in early spring and produce large leaves that can shade out other plant species. Infestations can dominate stream banks and reduce sight lines along roads, fences, and rights-of-way. Knotweed threaten biodiversity and disrupt the food chain by reducing available habitat and increasing soil erosion potential.
Stream banks are at particular risk as exposed knotweed roots break off and float downstream to form new infestations.
Knotweed can reduce or eliminate access to water bodies for recreation activities including fishing, swimming, boating, canoeing, and kayaking.