Home Office guidance has made it clear that new remedies for anti-social behaviour cover damage caused by Japanese Knotweed, with the potential for large fines.

Japanese Knotweed is an "invasive non-native plant" originally introduced to the UK as an ornamental plant. It is now better known for its destructive force than its beauty; its network of rhizomes (underground root-like stems) can spread more than four metres down and seven metres horizontally from the base, and break through tarmac and cement. It can cause structural damage to buildings and drainage and is extremely difficult to fully remove. Lenders are keen to establish whether any Japanese Knotweed is present on a property, and can be reluctant to lend if it is because of the damage it can cause (and the liability that imposes upon a landowner).

Having Japanese Knotweed is not in itself an offence but for many years offences have included allowing it to spread or become a nuisance to others, and planting it. The nature of Japanese Knotweed complicates compliance – even a tiny fragment of the rhizome network can cause the plant to regrow, and rapidly. Removal must be exhaustive at the site but also ensure that debris is not carried to another location where it can establish itself. Using herbicides usually takes three years for the plant to become dormant, and soil contaminated by the plant cannot go to normal landfill, so careful planning is required and suitable guarantees should be sought following professional removal.

The Anti-social Behaviour, Crime and Policing Act 2014 does not refer to Japanese Knotweed but the Home Office has issued guidance stating that the Act covers unreasonably failing to control or prevent the growth of Japanese Knotweed. Local councils and police can issue Community Protection Notices (after a written warning) to those whose unreasonable conduct is having a detrimental effect (of a persistent or continuing nature) on the quality of life of those in the locality. Breaching a notice requirement can be a criminal offence and lead to fines of up to £2,500 for an individual and £20,000 for organisations. The council can even step in and address the problem directly, initiated by those affected making a request to the council (if a certain threshold is met).

The fines are getting larger and a Japanese Knotweed desk top search with full enquiries of the seller should be considered as a matter of course, particularly for major developments. Specialist surveyors and consultants should be involved at as early a stage of the acquisition process as possible.

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