Japanese Knotweed is a strong-growing plant that is notoriously difficult to eradicate. It has a rapid growth rate, so there is a risk that it could quickly spread to adjoining land. If you own or occupy land that is affected by Japanese Knotweed, it is important that you take steps to prevent its spread to land owned by your neighbours. This may be a particular issue for landowners who have substantial tracts of land and therefore may find it difficult and time consuming to monitor its presence and growth.

If left untreated, Japanese Knotweed can cause physical damage to property and so its presence can affect the valuation of an affected property. This might result in landowners facing difficulties when trying to obtain a mortgage. Any treatment to eradicate Japanese Knotweed must be effective as even a small piece of root left in the ground can reinfest the land. The cost of removal and treatment are substantial and the Government has estimated the costs of eradicating it from all of the UK at £2.6billion.

Once removed, Japanese knotweed is likely to be classed as controlled waste. This means that depositing Japanese Knotweed in or on any land without a permit, or in a manner likely to cause pollution to the environment may be an offence under section 33 of the Environmental Protection Act 1990. It is important for landowners to bear this in mind when taking steps to remove Japanese Knotweed from their land.

The Anti-Social Behaviour, Crime and Policing Act 2014 (“the 2014 Act”) may also have an impact on landowners affected by Japanese Knotweed. Section 43 of the 2014 Act provides local authorities with the power to serve a community protection notice on an individual or body if it is satisfied on reasonable grounds that both the conduct of an individual or body is having a detrimental effect, of a persistent and continuing nature, on the quality of life of those in the locality and is unreasonable. Although the 2014 Act does not specifically refer to Japanese Knotweed the Home Office’s information note emphasises that these new powers are intended to be flexible and there is therefore a possibility that they will be used against an occupier failing to clear Japanese Knotweed.

The case of Waistell and Another v Network Rail Infrastructure Limited provided some guidance about when liability to a neighbouring landowner might arise.

The Decision

The Court considered the duty on a landowner whose land is affected by Japanese Knotweed to prevent it from spreading to neighbouring land.

The case was brought by two owners of semi-detached bungalows. The land to the rear of the bungalows, which was owned by Network Rail, had had a large stand of Japanese Knotweed growing on it for approximately 50 years.

Private nuisance will usually be caused by a person doing something on their own land, which they are lawfully entitled to do, but which becomes a nuisance to neighbouring land. In order for liability to arise, the damage or interference must be substantial. Loss arising from private nuisance can be either actual physical damage or unreasonable interference with property rights causing loss of enjoyment of the property.

If there is a nuisance, the landowner owes a duty of care to neighbouring landowners to do what can reasonably be expected of him in his individual circumstances (Goldman v Hargrave).

The claimants were unsuccessful in their argument that the encroachment of the Japanese Knotweed on to their land was in itself actionable. They could not demonstrate any physical damage to their properties and so were unable to show the necessary loss.

However, the Court accepted that the ability to dispose of a property at is proper value is an extremely important part of an ordinary householder’s enjoyment of their property (Bridlington Relay Limited v Yorkshire Electricity Board). As such, the Court concluded that the diminution in the value of the claimants’ properties as a result of the presence of the Japanese Knotweed was an interference with their quiet enjoyment.

Having concluded that a nuisance had arisen, the court went on to consider whether Network Rail had sufficiently discharged its duty to do what could reasonably be expected of it in the circumstances. Network rail sought to argue that, although the Japanese Knotweed had been growing on the land for approximately 50 years, it did not have knowledge of the impact it could have on mortgages secured against the property until the Royal Institute of Chartered Surveyors and the Property Care Association issued guidance on the subject in 2012/2013.

The court accepted Network Rail’s date of knowledge, but held that its treatment of the Japanese Knotweed since that date had been insufficient to discharge its duty. Network Rail had treated the Japanese Knotweed in 2013, 2015 and 2016. The evidence demonstrated that the treatment in 2013 had not focused on the whole stand of Japanese Knotweed and had therefore only been a partial treatment. It also showed that the stems of the Japanese Knotweed had been damaged prior to the treatment in 2016 and this rendered the treatment less effective.

In any event, the court found it inadequate that Network Rail had failed to treat the Japanese Knotweed at all in 2014. Whilst the Court accepted that Network Rail had limited resources that it could allocate to this issue, it found that having taken the decision to treat the Japanese Knotweed and allocated its resources accordingly, it could not then be argued that the lack of resources was an explanation for the inefficiency of the treatment.

Network Rail was ordered to pay damages to the claimants to cover a treatment package for the Japanese Knotweed and for the residual diminution in the value of their properties.

This decision in this case could lead to a large number of claims for landowners. Indeed, this case is of particular concern for those individuals or bodies who own large areas of land and therefore have difficulty in monitoring the presence or spread of Japanese Knotweed. If landowners are aware of Japanese Knotweed growing on their land, steps need to be taken to eradicate or limit the spread of the plant, particularly when there is a risk of encroachment on neighbouring land. If claims are brought by neighbouring landowners, damages may include the cost of removal or treatment, remedial works to damaged property and the diminution in value of the affected property.

This was a County Court judgment and there is the possibility that it will be appealed or considered by a higher Court in the future. However, in light of this judgment landowners should take steps to safeguard against claims as early as possible.