By Emily Spiler, Columbia Shuswap Invasive Species Society

Knotweed

Take a look out your back door to check for this invader.  Knotweed is an incredibly invasive perennial, and is classified as “noxious” under the BC Weed Control Act. There are four different species of knotweed found in BC: Bohemian, Japanese, Himalayan, and Giant. Originally brought over from Asia, this bamboo-looking plant wreaks havoc in backyards. Gardeners in the region likely share this plant unknowingly, and it has been nicknamed ‘False Bamoo.’ Knotweed has been found throughout Canada and B.C., including the Revelstoke, Shuswap and Columbia Regions.

Knotweed taking over an ecosystem.
Knotweed taking over an ecosystem.

This invader grows extremely large and fast — with reports of it growing over six centimeters per day (the stems can grow up to five metres in height!) Knotweed roots can grow up to three metres deep and 20 metres across. If stem or root fragments are left behind or mowed it can re-sprout, making it difficult to eradicate. Knotweeds can thrive just about anywhere, but habitats that are particularly high risk include along ditches or stream banks where plant material can be carried downstream.

Why is Knotweed so terrible?

Knotweeds are a serious ecological threat to our native biodiversity and habitats. Knotweeds grow in extremely dense patches, making it nearly impossible for anything else to grow. It can suppress other desirable or native species by hogging essential resources needed for growth such as space, sunlight, water, and nutrients. They have the potential to disrupt habitat for native species such as salmon, impact the food chain, and increase soil erosion.

Early stages of Knotweed growth.  Remove this plant from your property before it spreads.
Early stages of Knotweed growth. Remove this plant from your property before it spreads.

Additionally, many social and economic impacts can result from a knotweed infestation including property or infrastructure damage, reduced visibility along roadways, and reduced access to water bodies affecting recreation.  Knotweeds are known to grow through cement and can damage your foundation, driveway and septic system.

How do you get rid of Knotweed?

Removing Knotweed from an ecosystem can be challenging but is possible.
Removing Knotweed from an ecosystem can be challenging but is possible.

Getting rid of knotweed will take hard work and dedication, but it is possible. Many organizations discourage manual removal or digging because any small fragments can re-grow into several more plants. One of the most effective treatments is to use a specially-selected herbicide that will attack knotweed’s deep root-systems, and applied by a certified pesticide applicator. If any plant material is removed, it should be brought to the landfill for deep burial. Disposal should be done carefully and responsibly in sealed bags so that plant material is not spread while being transported.

Bamboo-like stems of a Knotweed plant.
Bamboo-like stems of a Knotweed plant.

To prevent the spread of knotweed, learn how to identify this plant and avoid purchasing or sharing it in gardens. You can also report infested areas using B.C.’s “Report-A-Weed” app on your phone. To keep Revelstoke knotweed-free and protect our natural resources, spread awareness, and keep an eye out for this invasive plant!

Watch Knot on my property! for more information about the dangers of Knotweed.

More TIPS for knotweed management can be found at:

Knotweed TIPS

The Columbia Shuswap Invasive Species Society is a non-profit organization dedicated to the prevention, management and reduction of invasive species in the Columbia Shuswap Regional District. CSISS is thankful for the generous support of the Columbia Basin Trust, the Columbia Shuswap Regional District, the Ministry of Forests, Lands and Natural Resource Operations, and the Ministry of Transportation and Infrastructure.

To learn more about invasive species in the Columbia Shuswap region please visit: http://www.columbiashuswapinvasives.org

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