Several Walloon river contracts today call for vigilance. While Japanese knotweed isn’t dangerous, it smothers everything in its path.
If you live along the Ourthe, you may have noticed this. Japanese knotweed tends to proliferate, following the floods of summer 2021. This is also the case along the Amblève, the Lesse or the Vesdre.
Faced with this observation, several Walloon river contracts are now calling for vigilance. This exotic plant is not dangerous, but very invasive. “Japanese knotweed, as its name suggests, comes from Asia and more particularly from Japan. It is an extremely effective invasive plant“, explains Xavier Vicca, project manager at the Ourthe river contract. “It will scatter wildly and completely smother all surrounding vegetation, as nothing grows underneath.“.
Individuals who have seen their garden covered with water during the floods must be vigilant: to avoid being invaded, they must act quickly. A single cm of rhizome is enough to revive a Japanese knotweed. To get out of it, you have to pull out the young cuttings as quickly as possible, then burn them or throw them in a garbage bag at the nearest container park. It is also a good idea to contact your Rivière contract to report the appearance of cuttings on your land.
To recognize it, it’s quite simple, it is somewhat comparable to bamboo, the trunk has segments with rings, and the stem is covered with reddish stripes. The leaves are a bit neon green and have a shape close to a heart.
Xavier Vicca therefore travels the banks of the Ourthe from La Roche to Liège and identifies the knotweed cuttings that he photographs, locates them on a map via his tablet and then destroys them. A follow-up is then ensured in the hope that the plant does not grow back a few months later. His mission is spread over two years.