Viewed as an attractive ornamental garden plant when initially introduced to the UK in Victorian times, Japanese knotweed is now regarded as something much more sinister. Unusually aggressive, highly invasive, capable of regenerating from the smallest piece of rhizome, difficult and expensive to eradicate ... It's destructive nature (being capable of penetrating tarmac, building foundations and drains, causing considerable and costly damage to property and infrastructure) is becoming an ever increasing concern for landowners.
The presence of Japanese knotweed can have an adverse effect on the value, marketability, mortgageability and insurability of a property. Although the hazardous weed is more prevalent in urban areas, growing on derelict land and also along railway lines and canals, where it was historically utilised to stabilise embankments, it can be found in all parts of the country affecting all types of land, including gardens of residential properties.
It may therefore be considered surprising that there is no statutory positive obligation to eradicate or even keep Japanese knotweed under control. However, landowners and occupiers could face criminal and civil liability for the encroachment of Japanese knotweed onto neighbouring land or the adverse effect its presence may have on the amenity of an area under a myriad of legislative provisions under the Wildlife and Countryside Act 1981, the Environment Protection Act 1990, the Town and Country Planning Act 1990 and the Anti-social Behaviour, Crime and Policing Act 2014 or through a claim for private nuisance.
Depending on the offence, penalties can include fines (in some cases unlimited) and even imprisonment. Since the coming into force of the Infrastructure Act 2015, environmental authorities also now have the right, in some circumstances, to compel landowners to manage invasive species such as Japanese knotweed by making Species Control Orders.
Perhaps more interestingly, and topically in view of the decision in the County Court case of Waistell v Network Rail Infrastructure Limited earlier this year, a claim can be brought by an aggrieved party against a neighbouring owner or occupier if the presence of Japanese knotweed on the neighbour's land causes damage to or interference with the use and enjoyment of that party's land.
That case involved separate claims brought by the owners of two properties in South Wales abutting an embankment owned by Network Rail. Japanese knotweed had been growing on the embankment for decades, long before the claimants purchased their respective properties. Network Rail had been aware of the presence of Japanese knotweed in the relevant section of the embankment since 2008 and had in fact taken some steps to treat the weed. The claimants complained to Network Rail in 2013 alleging that their properties were blighted due to the presence of Japanese knotweed on Network Rail land and this made them unsellable.
The judge held that encroachment by the plant rhizomes was not actionable unless they had caused physical damage and in this case there was no direct evidence of such damage having been caused to either property. However, the court found that Network Rail had not nonetheless discharged its duty of care in failing to tackle the Japanese knotweed effectively and held that there was an actionable private nuisance as the Japanese knotweed interfered with the amenity value of the claimants' properties, because they could not sell them for the full market value. Claimants were awarded damages in lieu of an injunction, representing the diminution in value of the properties and costs for effective remediation of the knotweed.
It therefore seems, at least for the present, that the mere presence of untreated Japanese knotweed in close proximity to one's property (more specifically, within seven metres of a built structure on neighbouring land) may be sufficient to bring a successful action in private nuisance for interference with its use and enjoyment. There is no requirement for Japanese knotweed to be causing physical damage to buildings and other structures or for rhizomes to be located in the soil of the claimant's property for a claim to be successful. It remains to be seen whether the decision in Waistell v Network Rail Infrastructure Limited will open the floodgates for claims for damages by parties suing their neighbours because of mere presence of Japanese knotweed on their land.
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