Alert: Japanese knotweed is still spreading! In spite of all our best efforts, this plant is rapidly invading Britain, mainland Europe, United States, Canada and Australia. The eradication and removal of Japanese knotweed is essential to control this highly problematic weed.
Japanese knotweed is a nice plant and many people would simply ask where the problem stands. Well, Japanese knotweed is not native to Europe and was imported in the UK without its natural enemies. Indeed, the plant grows in harmony with the Japanese environment, where nobody ever considered being invasive specie.
Originated from the volcanic area around the mount Fuji, Japanese knotweed is an extremely resistant plant. Above all, many insects and fungi that attack the weed in its native context are absent in Britain. As a result, the plant has an unfair advantage over our native plants.
Control of the plant is fundamental and it has been estimated at over •£1 billion. Methods of control mainly rely on chemicals, but these are often weak in the long run, as the rhizome system spreads extensively underground. Thus, treatment often needs to be repeated over a long period of time.
How does chemical control occur? This method is risky when applied near water or sensitive vegetation. In both cases, consent must be sought from the Environment Agency. Herbicides are usually based on glyphosate and are sprayed on the plant.
Such a treatment must be repeated over several years together with a constant monitor of the trated areas. In this way, a complete control of Japanese knotweed could effectively take place.
In the sort run, Japanese knotweed can be cut, but it is important to understand that it will not eradicate the plant. It is necessary to make sure that all fragments of rhizome are not spread. Above all, any waste material from cutting should be disposed of according to the Environmental Protection Act 1990.
Natural control is a good potential method of control, implemented through the use of living organisms. This occurs by re-introducing some of the specialist natural enemies that exert control on it in its native scenario. In one word, those enemies that are not present in Britain. Interestingly, this practice involves going back to where the invasive weeds originated from and finding the natural enemies that keep the weeds balance with the surrounding environment. Natural control is a sustainable alternative.
