Japanese knotweed is a non-native invasive plant that was brought to North America from Japan in the mid-nineteenth century as an ornamental garden plant. There is also a similar form of Knotweed also found in Nova Scotia called Giant Knotweed. (Polygonum sacchalinese) Knotweed has become a threat in the wild and causes serious problems by displacing native flora and causing structural damage. Japanese Knotweed is an herbaceous perennial and despite it’s bamboo like appearance is a member of the buckwheat family. No viable seed has been recorded except as a result of hybridization. This means the plant regenerates not only via an extensive and rapidly growing rhizome system but also from fresh root and stem material. As little as 10mm in length or 0.7g fresh weight of rhizome will allow knotweed to regenerate and form a new plant.

Description: The stems are green with red or purple specks, hollow and similar to bamboo, and can grow up to 2-3m tall, forming dense cane-like clumps. The leaves are green, shield or heart-shaped, with a flat base and are up to 12cm long. Clusters of creamy flowers appear on the tips of most stems from August to October but produce sterile seeds. The roots consist of rhizomes, which are yellow when cut, but can spread to a depth of 3m and radius of 7m.

What to do if you have Japanese knotweed on your property:

Deal with any Japanese knotweed rapidly to prevent its spread to neighboring areas and property.

Inject plants ideally in spring and late summer/autumn, using a non persistent, general-purpose herbicide e.g. Glyphosate. There are many trade names for weed killers containing glyphosate such as Roundup. The best and most effective time to inject is summer/autumn, when the plant is flowering and the foliage is conducting the most nutrients to the rhizome to build food reserves.  The cane-like stems die-back but still persist over the winter. Knotweed is a perennial.

Injection guns can be loaned from ACAP Cape Breton and 3 hardware stores in Ingonish, NS. Be sure to always wear gloves and eye protection when using Glyphosate.

Make sure all plants are completely dried out first and then either disposed of in black garbage bags or burned. Do not compost. If you would like to borrow the gun at no cost there is a 20 min training session on knotweed and proper gun use. To borrow a gun or schedule training please contact Wayne Williams at 567-1628











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