The Wildlife and Countryside Act 1981 / Wildlife (Northern Ireland) Order 1985 controls the spread of Japanese knotweed into wild habitats. Part I (WILDLIFE – Miscellaneous), Section 14, Clause 2 of the Act states:
"… if any person plants or otherwise causes to grow in the wild any plant which is included in Part II of Schedule 9, he shall be guilty of an offence."
Schedule 9 (ANIMALS AND PLANTS TO WHICH SECTION 14 APPLIES), Part II (PLANTS) lists Giant Hogweed, Giant Kelp, Japanese knotweed and Japanese seaweed (though more species have subsequently been added). It is therefore a defence to the provision of the Act to undertake all reasonable steps to control Japanese knotweed on, or infringing onto, your land. This means it is legal to grow the plant on private property but it must not be allowed to escape. It should be noted, though, that the wording of the Act can be open to interpretation, as what constitutes “in the wild” is not properly defined.
The plant is not cited under any legislation that requires its presence to be notified to either DEFRA (Department for Environment Food and Rural Affairs) or local planning authorities, and neither is it listed under The Weeds Act of 1959.
The responsibility for the control of knotweed usually rests with the landowner or tenant of the land. The Environment Agency or local government are not obliged to control it on behalf of other landowners. Similarly, disputes between neighbours regarding problems associated with the plant are largely a civil matter and third party litigation can result if knotweed is allowed to spread from one property onto that of an adjacent landowner.
Penalties for causing an infestation can include imprisonment for up to two years (if the case ends up in the Crown Court) or a large fine, or both – although these kinds of penalties are usually reserved for fly tipping offences. DEFRA has also suggested that local authorities could make landowners deal with knotweed infestations that “adversely affect” the amenity of the neighbourhood, under the Town and Country Planning Act 1990 – although different local authorities have responded to this suggestion with varying levels of enthusiasm.
If you have this invasive weed infringing onto your land from neighbouring property, the best solution is to co-operate with the neighbouring landowner, if possible, and co-ordinate your control efforts by sharing costs or labour, for instance. If you do not know who owns the adjoining land, or you are in dispute with your neighbour, current legislation sadly offers little support.
If the problem persists and is disturbing the enjoyment and maintenance of your garden it might amount to a “nuisance”. In this case you may be able to get an order served by the Department of the Environment on to the owners to prevent the weeds or pests from spreading. The Environmental Protection Act defines a private nuisance as an "unlawful interference with a person's use or enjoyment of land, or some right over, or in connection with it" (Read v Lyons & Co Ltd. 1945). Success along this route varies from Local Authority to Local Authority, as it is dependant on a subjective definition of the term “unlawful interference.”
If you are not able to reach an amicable solution with your neighbour your only recourse may be civil litigation. Many solicitors may be reluctant to pursue a course of action without precedent, so you may wish to cite the following well-documented case:
Leigh County Court, Case Number 93.00392, June 1995
Flanagan vs Wigan Metropolitan Borough Council.
Mr Flanagan brought action against his local authority for allowing knotweed to grow from adjacent amenity land into his garden. Mr Flanagan won and the Council were required to treat with herbicide a 1 metre-wide strip of knotweed along the property boundary for 3 years and install a reinforced concrete barrier to prevent further infestation. They were also liable for costs incurred.
Be advised, though, that civil litigation is expensive and time-consuming and there is no guarantee that you will win. In short, it should only be regarded as a last resort when all other avenues of negotiation have failed. Therefore we can only recommend you seek legal advice before proceeding further.
Prevention may be deemed the more feasible solution. Spread of knotweed rhizome can be stopped from getting into your garden by sinking a specialist vertical membrane barrier at least 2 metres deep along the boundary of your property. Be advised, though, that once the knotweed arrives at your boundary you will need to undertake annual ‘mop up’ herbicide treatments along your fenceline to reduce the pressure the knotweed will put on the barrier and thereby reduce the risk of infestation to your property. If you are considering installing such a barrier it is highly recommended that you consult an expert. Please note that disposal of cut knotweed – including the contaminated soil it is growing in – must be conducted in accordance to strict guidelines. Disposing of plants to Civic Amenity sites is unacceptable as this waste is often composted and recycled. Such treatment will not generally kill crowns or rhizomes of plants and this will simply ensure the knotweed infestation is spread to new areas.
Knotweed waste must be disposed of by prior arrangement at a licensed landfill facility, in accordance with the Environmental Protection Act 1990 and the Environmental Protection (Duty of Care) Regulations 1991. Should you have any information regarding the fly tipping or incorrect disposal of knotweed material this should be reported to the Environment Agency immediately on their 24-hour freephone number: 0800 80 70 60.
A review of the Wildlife and Countryside Act was included in the National Environment and Rural Communities Act 2006. A number of amendments were suggested during the consultation process, including the issue of a code of practice (not unlike the Ragwort Control Act of 2004), and adding such non-native invasive and injurious species as Japanese knotweed, Giant hogweed, Himalayan balsam, and Floating pennywort to the terms of The Weeds Act. Sadly many of these suggestions were lost during the various readings of the original Bill, though under Part 3, Schedule 51 (1) (b) the Secretary of State is empowered to issue or approve a code of practice relating to animals or plants listed in Schedule 9 of the 1981 Act. A real opportunity was missed here to tighten up the indistinct wording of the Wildlife and Countryside Act.
Further consultation on the Act began in November 2007 specifically to review the wording of Schedule 9. This will emerge as an Act of Parliament towards the end of 2008, but the focus of this consultation is to revise the list of species subject to Schedule 9, so it is unlikely to tighten up the wording. It makes one wonder whether we will ever see firm unequivocal legislation in the UK in regard to knotweed infringement from neighbouring properties.
Specifically in the agricultural sector, legislation relating to Japanese knotweed and other invasive species includes The Common Agricultural Policy Single Payment and Support Schemes (Cross-compliance) (England) Regulations 2005, which came into effect in January 2006 and replaced the earlier 2004 Regulations. According to Paragraph 9, a farmer “must take all reasonable steps” to prevent the spread of Japanese knotweed, as well as Rhododendron ponticum, Giant hogweed and Himalayan balsam, on their land or onto adjacent land. Similar clauses exist in The Common Agricultural Policy Single Farm Payment and Support Schemes (Scotland) Regulations 2005 (PART 4, Paragraph 12, Sub-paragraph 7) and The Common Agricultural Policy Single Payment Scheme (Set-aside) (Wales) Regulations 2005 (Paragraph 4, Sub-paragraph 7).
Further, there is a requirement in Scotland in the maintenance of agricultural land to control “statutory weeds, giant hogweed and Japanese knotweed” under SCHEDULE 2, Paragraph 14 (c) of The Rural Stewardship Scheme (Scotland) Regulations 2001.