Knotweeds are designated as provincially noxious under the Weed Control Act.

Rossland leading the way in knotweed management in the West Kootenay region.

Knotweed is a highly invasive plant that negatively impacts infrastructure and increases erosion due to its extensive root system that can grow up to three meters deep and twenty meters wide. The damage that knotweed causes can decrease property values, increase taxes and cause environmental harm.

Knotweed is so aggressive it can grow through the smallest crack in concrete.

How did knotweed end up in Rossland gardens? The four varieties of knotweed – Japanese, Giant, Himalayan and Bohemian – are originally from Asia, they were introduced to North America as a decorative garden shrub. Nicknamed “false bamboo” this tall and pretty plant was an easy sell because it is fast growing (6 cm per day) and requires minimal attention.  Little did these gardeners know that the plant’s aggressive nature would end up causing a number of economic, social and environmental problems to the City in the future.

Invasive knotweeds (Fallopia ssp. (Polygonum ssp.))
Invasive knotweeds (Fallopia ssp. (Polygonum ssp.))

The City of Rossland has adopted a bylaw (BYLAW #2637) requiring all property owners to ensure that their land is free from knotweed. In order to assist landowners with knotweed eradication, the City has offered a rebate of 50% of the cost up to a total of $400 to landowners who conduct knotweed control using herbicide on their private land. Mechanical control of knotweed such as cutting, digging, smothering or burning has proven to be ineffective and can contribute to its spread. Knotweed is extremely aggressive; a new infestation can occur from as little as 0.7 grams of stem or root tissue.

“Knotweed is listed as a priority species for the Province of BC and the Central Kootenay Invasive Species Society (CKISS). We applaud the efforts of the City of Rossland for being the first municipality to take firm action on knotweed eradication. Our hope is that other municipalities in our region follow their lead.” states Erin Bates, CKISS Operations Program Coordinator.

In addition to the bylaw, the City of Rossland has been treating knotweed sites that are located on city land for the past three years. The results of the treatments have been promising.