You are legally required to preserve any invasive vegetation on the land under control, this contains Japanese knotweed. As being the plant is labelled as controlled squander by the Wildlife and Countryside Act 1981 [8], it is prohibited to easily take out Japanese knotweed from your land and dump it https://japaneseknotweedcontrol77543.thezenweb.com/5-simple-statements-about-japanese-knotweed-control-explained-76296586