You are legally necessary to retain any invasive crops on your land beneath control, this incorporates Japanese knotweed. As the plant is labelled as controlled waste through the Wildlife and Countryside Act 1981 [eight], it is unlawful to easily remove Japanese knotweed from your land and dump it somewhere else. https://japanesecontrol33109.humor-blog.com/36541315/japanese-knotweed-control-an-overview