147: Ignore Japanese Knotweed at your peril

Homeowners are being warned not to knowingly allow Japanese knotweed to grow on their property unchecked. Truro County Court has recently heard a dispute between adjoining residential property owners where Japanese knotweed was found to be growing and an injunction was ordered forcing one owner to have to treat the encroaching knotweed.

Japanese knotweed is an extremely invasive plant that can cause severe physical damage to land and buildings through its spreading roots. It is not a criminal offence to have Japanese knotweed on your land, but it can be an offence not to control its spread.

Facts

Mrs Line owned a large area of beachside land in Cornwall comprising a house, woods, land for grazing and land used for public car parking. In 2002, she sold the house to Mr & Mrs Smith for £200,000. Japanese knotweed was present on Mrs Line’s retained land and had spread onto the property bought by Mr & Mrs Smith.

The Smiths complained to Mrs Line, who in turn tried to claim the knotweed had actually spread from their land onto hers. The Smiths argued the presence of Japanese knotweed and failure to eradicate it had de-valued their house (now worth £500,000) by £50,000.

By 2013, the Smiths had carried out treatment on their land to successfully eradicate the Japanese knotweed, but continually requested that Mrs Line should take steps to remove it from along the boundary with their land.

The Smiths brought a claim in nuisance against Mrs Line seeking an injunction and / or damages. Joint experts were instructed who concluded that the Japanese knotweed actually started on Mrs Line’s property and encroached onto the Smiths’ land. The Smiths argued nuisance on the basis of:

• physical encroachment of the knotweed; and
• interference with their use and enjoyment of the land.

Decision

The judge found that the Smiths’ land had not actually been damaged. However, Mrs Line had failed to comply with her duty of care and the knotweed on Mrs Line’s land was interfering with the Smiths’ use and enjoyment of their property. The Smiths were granted a mandatory injunction requiring Mrs Line to contract with a reputable contractor to treat the Japanese knotweed on her property, plus payment of the Smith’s costs.

The judge referred to the 2017 judgement in Waistell (& Williams) v Network Rail (covered in our previous blog). In this case, the presence of Japanese knotweed on Network Rail’s embankment had unlawfully interfered with both Mr Williams and Mr Waistell’s quiet enjoyment of adjoining houses. Network Rail was ordered to pay damages to the claimants representing the cost of the treatment works and for the diminution in value of the properties.

Comment

The outcome of these cases is clear. Property owners should consider taking precautions to prevent the spread of Japanese knotweed from their land onto neighbouring land or face the possibility of action in the courts.