Japanese knotweed is an aggressive foreign invader. Its presence on land can have serious consequences for property owners. Following publication of a new RICS information paper on the issue, Sarah Brown and Helen Lamb outline the legal implications.
Japanese knotweed was first introduced to the UK in the nineteenth century as an ornamental plant but has since become widespread in a range of urban and rural areas.
Unfortunately the effects of its aggressive spread have not been welcomed. It is now described by the Environment Agency as “the most invasive species of plant in Britain” and was named by the World Conservation Union as one of the top 100 worst plant species. Its effects appear to live up to this ferocious reputation and annually it is estimated to cost the UK economy in the region of £166 million to control and clear.
The presence of Japanese knotweed can cause misery for landowners. It has very strong root systems which can cause structural damage to foundations, buildings, flood defences, roads, paving and architectural sites. Its presence may also delay development projects and reduce property values. In severe cases, it has even resulted in the demolition of affected buildings.
A criminal problem?
It is not an offence to have Japanese knotweed on your land and there is no legal obligation to notify anybody but a landowner may still find themselves on the wrong side of the law:
- Criminal liability under the Wildlife and Countryside Act 1981: Under section 14(2) of this Act, it is a criminal offence to plant or otherwise cause to grow in the wild any plant which is included in Schedule 9 of the Act including Japanese knotweed. The maximum sentence for the offence on indictment is an unlimited fine and/or two years’ imprisonment.
- Criminal liability under the Environmental Protection Act 1990: Soil and waste containing Japanese knotweed is likely to be deemed to be “Controlled Waste”1 under the Environmental Protection Act 1990 and it is an offence to:
- deposit, treat, keep or dispose of controlled waste without an environmental permit; or
- to keep, treat or dispose of controlled waste in a manner likely to cause pollution of the environment or harm human health.2
The maximum sentence for either offence is an unlimited fine and/or two years’ imprisonment.
The Environmental Protection Act 19903 places a duty of care on any person who imports, produces, carries, keeps, treats or disposes of controlled waste. The duty of care requires that all reasonable steps are taken to keep waste safe. Waste must only be given to a suitable licensed waste contractor and appropriate documentation must be completed and retained to demonstrate compliance with the duty of care. Again, it is a criminal offence to breach this duty of care.
Developers and contractors in particular, therefore, need to be confident that any topsoil is sourced carefully.
Under Part 2A of the Environmental Protection Act 1990 (the contaminated land regime), land is deemed to be contaminated by the presence of a substance which is hazardous to health or the environment and this includes harm caused to property. Due to its damaging nature Japanese knotweed could fall into this category. However, since the regulator has other legislative tools available which are specifically tailored to this problem - most particularly the Wildlife and Countryside Act 1981 as described above – it seems unlikely that the Part 2A regime would be used to deal with knotweed contamination.
- Civil liability for Private Nuisance: Allowing Japanese knotweed to spread onto neighbouring land could constitute a private nuisance and result in a claim for damages.
- Town and Country Planning Act 1990: The Town and Country Planning Act 19904 allows a local planning authority to serve a notice on a landowner where an area is “adversely affected by the condition of the land in their area”. This notice will specify steps for remedying the condition of the land and, at the discretion of the local authority, may be used to require a landowner to remove or otherwise control Japanese knotweed.
- European Union Invasive Species Legislation: The European Commission is concerned about the effect that invasive species like Japanese knotweed are having on Europe’s biodiversity and a consultation on possible new EU legislation dealing specifically with invasive alien species closed on 12 April 2012. This addressed issues such as the possibility of applying the “polluter pays” principle into any new legislation. If implemented, the EU-wide legislation could result in further restrictions and liabilities on landowners in relation to Japanese knotweed in the future.
Getting rid of the super-weed
The main options for removal of Japanese knotweed are chemical control and physical removal, which are both potentially costly and time-consuming. The Environment Agency has produced a Knotweed Code of Practice which provides guidance to help developers manage, destroy and dispose of knotweed legally. The RICS (see below) suggest that repeated chemical control may be the most economical treatment option in a residential context.
Biological solutions to the problem have also been considered and the government is currently trialling the release of a predator insect – the psyllid - in an attempt to identify a new method of control. The controlled release of the highly specialist psyllid is almost two years into the release phase and, if successful, should restrict the growth of Japanese knotweed, slow its capacity to spread as vigorously and enhance the effectiveness of other management efforts.
Whatever method is used, it is vital that the source of contamination is identified to avoid further spread after treatment. It must also be disposed of properly to avoid further contamination.
A number of pieces of legislation may impose liability for improper removal and disposal:
- The Control of Pesticides Regulations 1986 imposes obligations on any person who uses a pesticide to take all reasonable precautions to protect the health of humans, animals and plants, safeguard the environment and avoid the pollution of water.
- The Hazardous Waste Regulations 2005 contain provisions about handling and movement of hazardous waste. Material containing Japanese knotweed which has been treated with certain herbicides may be classified as hazardous waste.
- The Waste (England and Wales) Regulations 2011 require that waste is disposed of without endangering human health, or by using processes or methods which could harm the environment or adversely affect the countryside. In order to comply with these Regulations the movement of Japanese knotweed (a controlled waste) offsite must be undertaken by a licenced waste contractor and covered by a waste transfer note, a copy of which must be retained for at least two years after the date of the waste transfer.
- The Environmental Permitting Regulations 2011 impose an obligation to obtain an environmental permit (or exemption) on any organisation intending to treat or dispose of the controlled waste itself.
To assist financing knotweed removal, land remediation tax relief which was introduced in 2001 allows companies to claim a deduction in corporation tax for revenue and capital expenditure in the remediation of contaminated sites. The cost of removing Japanese knotweed will qualify for this relief unless the material is sent to a landfill for disposal as waste. It will also be available regardless of when the contamination occurred, provided that the landowner did not plant or allow the Japanese knotweed to spread.
Implications for sales, lettings and financing
The legal duties imposed on owners of land containing Japanese knotweed and the cost of removal may impact upon the value and marketability of the land. Lenders may refuse to lend on properties which are affected, making a sale more difficult.
The normal principle of caveat emptor or “buyer beware” will apply on a property sale. This means that the seller has no duty to volunteer information concerning the physical condition of the property and it is the buyer’s responsibility to satisfy itself as to the condition by inspection and research.
Arguably, some of the standard pre-contract enquiries would require the seller to disclose its presence5 and a purchaser may supplement the standard pre-contract enquiries with a specific enquiry regarding Japanese knotweed. However, the usefulness of these enquiries is dependent on the seller’s reply and, whilst the seller will be liable for any misrepresentations, if they simply direct the buyer to rely on its own inspection then the buyer will be none the wiser and will have no recourse to the seller.
It is very unlikely that an environmental desktop report will disclose the presence of Japanese knotweed on a site since these types of report do not involve a site visit and rely only on information which is publicly available. Buyers who are concerned should therefore commission a specific assessment from an expert surveyor or environmental consultant.
If land affected by Japanese knotweed falls within a tenant’s demise, then the terms of the lease will dictate who is responsible for removing it. The lease may include specific provisions to deal with liability for environmental contamination which could determine the position. If not, then a tenant’s covenants to comply with statute or avoid committing a nuisance may well result in responsibility for removal falling within the tenant’s obligations.
As a final resort, it may be necessary to look at the repair obligations under the lease. The specific wording of the repair covenant will be important in determining whether or not removal of Japanese knotweed is covered. It is not clear whether the presence of knotweed can be regarded as disrepair but it could be construed as contamination which should fall within the tenant’s obligation to repair.
RICS Information Paper
To date, there has been no common approach to measuring the risks associated with Japanese knotweed. The new RICS information paper, Japanese knotweed and residential property,6 attempts to introduce objective criteria for categorising the risk in a residential context so as to introduce some consistency in this area.
The paper outlines four categories of risk, ranging from low to high, which vary according to the location of the weed in relation to habitable space and the boundaries of the property, as well as the level of damage to property features. It is envisaged that for properties falling within the most high-risk groups, further specialist advice will be sought to obtain a detailed assessment, management plan and cost estimates for remediation. It is hoped that those bodies involved in the treatment of Japanese knotweed will introduce national standards of remediation in line with the protocols set out by the RICS.
Currently, individual lenders adopt different approaches to lending decisions on properties affected by Japanese knotweed. Some refuse to lend at all and others are only willing to consider applications on a case-by-case basis. By introducing a more standardised approach to the assessment and treatment of the weed, it is hoped that residential mortgage lenders may be able to adopt a more balanced and consistent approach to lending decisions.
Japanese knotweed is a non-native species which is tenacious, aggressive and hard to stop. There is often little that a property owner can do to prevent contamination but once an invasion is discovered, a landowner must act with great care to avoid legal liability.
It can result in significant physical damage to buildings and hard-landscaping and necessitate costly and timeconsuming remediation works. Currently, there is no quick fix for this super-weed and a purchaser must rely upon its own investigations and enquiries in order to check for the presence of Japanese knotweed and avoid becoming tangled up in the first place. A previous version of this article was published in Estates Gazette on 28 April 2012
Identifying the Invader
The RICS Information Paper, Japanese knotweed and residential property, includes an identification guide to help valuers identify the plant. The main identifying features of Japanese knotweed are as follows:
- Lush green in colour
- Shovel-shaped leaves
- Bamboo-like stem
- Produces white flowers, usually between August to October
- Can grow up to 4m in height and by up to 10cm a day
A previous version of this article was published in Estates Gazette on 28 April 2012