We have been receiving reports of attempts at removal of the invasive non-native species Japanese knotweed by strimming which, as a charity working to restore rivers, is deeply concerning to us. It is an offence under section 14 of the Wildlife and Countryside Act 1981 to plant or cause this species to grow in the wild. This means that actions which cause the spread of Japanese knotweed, e.g. strimming, flailing or dumping contaminated material, may constitute an offence.

Japanese knotweed offences under this Act are enforced by the police. Therefore, if you see somebody causing the spread of Japanese knotweed, you should contact your local police station.

How to treat Japanese knotweed:


  • Hire Japanese knotweed removal professionals – who will use professional grade Glyphosate-based herbicides. Glyphosate must be applied to large stands in late summer/autumn after the plant has flowered. Large mature stands of Japanese knotweed will need to be treated for two or three years to achieve eradication (i.e. treat once a year in late summer/autumn).


  • DO NOT strim, flail or mow Japanese knotweed – this is a criminal offence under section 14 of the Wildlife and Countryside Act 1981, and will cause spreading.
  • Cut it – this will create controlled waste which must be carefully contained and disposed of in a specific manner.
  • Attempt to dig it up – the roots system is expansive and any that remain in the ground will give rise to new plants