Actions Japanese knotweed

ASL goes to war against invaders

Reynoutria japonica

You may have already seen these big bushes on the shore of the lake, along a river or a slope of an embankment, made of tall stems with beautiful white flowers and immense leaves, haven’t you?

Even if we can appreciate the aesthetic of this plant, called Japanese Knotweed, it is not indigenous at all. Its pioneer aspect enables it to survive easily at the native ones’ cost.

Indeed it presents a powerful capacity to incurably invade fields and prevent all other species to grow. A dense layer of different plant species quickly covers lakeshores, rivers and other embankment in summer, but in winter those places are empty and covered by dry stems.

Indeed, she presents a powerful capacity to irreparably invade the fields and prevent all other species to grow up. Lake edges, rivers and others embankment get quickly covert by a massive layer of vegetal on summer, letting dry stems and empty spaces on winter.

japanese knotweed caracteristics



    • High growth rate (to 3 or 4 centimetres per day ; 3 meters after a few weeks) ;
    • Effective rhizomes allowing an important grow back after winter, or a cut, and a good dispersion in the soil ;
    • Regrowth (or fascicle cuttings) even from a very small plant fragment, like a piece of stem or root ;
    • Emission of toxic substances preventing the growth of other plant species, thus taking control of a place ;
    • No parasites a tour latitudes since it is a foreign species (= an introduced species) ;
    • Only one weakness : it does not like the shade


Knotweed stop ! We need you, your friends and your family !

Are you interested in helping us in this long and difficult fight against the scourge of invasive plants? It is also the opportunity to live an outdoor adventure, good for your health and, why not, a good moment to meet people and share!

Therefore all labour forces are welcome to insure some regularity in the interventions. Thus a general movement is needed for our new action “Knotweed STOP”, particularly in the cantons of Geneva and Vaud and their surroundings as a first step.

Subscribe : or 022 736 86 20

You’ll receive more information about tasks you could accomplish, intervention sites and the schedule of periods where the vigorous actions will be done.

For more information : Lémaniques n°87 (page 4 to 6)

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