Japanese Knotweed Legal Issues

Causing the spread of knotweed may make you liable to prosecution.

Whose responsibility?

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Managing Japanese knotweed (Fallopia japonica) is the responsibility of the owner/occupier of the site. While there is no statutory requirement to control/eradicate this invasive plant, nor is it necessary to report its presence (it is not listed in the Weeds Act 1959), it is advisable to take action quickly to control its spread.

It is an offence under the Wildlife and Countryside Act 1981 to plant or cause Japanese knotweed to grow in the wild. This is enforced by both the Police and local authorities.

A magistrates‟ court can impose a maximum fine of £5000 or a maximum prison sentence of six months, or both. A Crown Court can impose an unlimited fine or a maximum prison sentence of two years, or both.

Allowing Japanese knotweed to spread onto neighbouring land could be considered to be a private nuisance but not a statutory nuisance.

Statutory Nuisance

For an issue to be a statutory nuisance it must unreasonably and substantially interfere with the use or enjoyment of a home or other premises, injure health or be likely to injure health.  Therefore Japanese knotweed can definitely not be a statutory nuisance.

Private Nuisance

Private nuisance is defined as the unlawful interference with a person’s use or enjoyment of land, or some right over, or in connection with it.   It allows landowners or tenants of leasehold properties who have a right to the land affected to bring action against the person responsible.  

Soil and waste containing Japanese knotweed is considered to have the potential to cause ecological harm. This is deemed “Controlled Waste or “Directive Waste‟ (Waste Management Licensing Regulations 1994).

It is an offence under the Environment Protection Act 1990 to deposit, treat, keep or dispose of controlled waste without a licence.  Exemptions from licensing are available in certain circumstances which are set out in Schedule 3 of the Waste Management Licensing Regulations 1994.

It is also an offence to keep, treat or dispose of controlled waste in a way which is likely to cause pollution of the environment or harm to human health.  A magistrates‟ court can impose a maximum fine of £20,000 or a maximum prison sentence of 6 months, or both. A Crown Court can impose an unlimited fine or a maximum prison sentence of 2 years, or both. 

The Environmental Protection Act places a duty of care on any person who imports, produces, carries, keeps, treats or disposes of controlled waste.

Their duty is to ensure that:

  • No-one else disposes of the waste unlawfully or in a way which is likely to cause pollution of the environment or harm to human health.
  • Waste does not escape.
  • Waste is only transported by a carrier that is either registered or exempt from registration by the Controlled Waste Registration of Carriers and Seizure of Vehicle Regulations 1991.

Breach of the duty of care is a criminal offence. The Environment Agency is responsible for enforcement and a person found guilty of an offence is liable to a fine not exceeding £5000 in the magistrates‟ court and to a fine in the Crown Court.

Japanese knotweed must be safely disposed of at an appropriately licensed landfill site. To ensure safe disposal, contaminated soils must be buried to a depth of at least 5 metres. A duty of care is also placed on all waste producers to ensure that a written description of the waste and any specific harmful properties is provided to the site operator.  Waste transfer notes must be completed when waste is transferred from one person to another.  Failure to comply with this is an offence.

Untreated knotweed is not regarded as a "Hazardous Waste‟ but material containing knotweed that has been treated with certain herbicides that persist in soil for extended periods with the possibility of leaching and causing harm to the surrounding environment could be. Additionally, excavated knotweed waste contaminated with high levels of heavy metals or other hazardous materials could be categorised as hazardous and must be disposed of at a licensed hazardous waste landfill site.

Treatment of knotweed using pesticides requires everyone to follow The Control of Pesticides Regulations 1986 and comply with Control of Substances Hazardous to Health Regulations 2002. All reasonable precautions should be taken to protect the health of human beings, creatures and plants, safeguard the environment and, in particular, avoid the pollution of water. Approval from the Environment Agency should be sought before application of pesticides in or near water.

In addition, to existing legislation, there are codes of practice which provide guidance concerning Japanese knotweed.

The Environment Agency's Knotweed Code of Practice is aimed at providing advice for managing knotweed on development sites.

The Non Native Species Secretariat (NNSS) website has a Horticultural Code of Practice developed by GB Administrations, Trade orgnaisations, NDPVs and Environmental NGOs.

More information about non-native species is available on the DEFRA website.