With its ability to crack concrete, block drains and undermine foundations, it is one of our most invasive and damaging plants.
When it comes to tackling Japanese knotwood – its very presence can slash the value of a home or make it unsellable – the Environment Agency’s rules are understandably strict. Anyone caught moving contaminated soil or cuttings faces a £5,000 fine and up to two years in prison.
So when a worker employed by the agency to deal with an outbreak on its own land was caught strimming the rogue plant and seen tossing remains into a stream, nearby homeowners were horrified.
Blight: Simon Walker in his garden, part of which he fenced off to stop the encroaching knotweed (circled)
The extraordinary breach of rules was captured on video by residents adjacent to the land – and now ten are suing the agency, claiming knotweed from its land has spread to their North London gardens – wiping more than £150,000 off the value of their homes.
Father-of-three Simon Walker, 36, who is leading the legal battle, said: ‘We filmed them at work, then watched as they threw the stalks and debris into the brook at the end of the garden.
‘They are breaking their own laws – it has to be disposed of in a controlled way. It could have easily spread to gardens downstream, with cuttings from the strimming flying everywhere.’
Knotweed did not show up on a survey when Mr Walker bought his £550,000 house in November 2014, but a neighbour later told him it was growing in his garden. Mr Walker claims it came from adjacent agency land.
It is also in other gardens and Mr Walker and his neighbours made repeated requests to the agency to deal with it.
Against the regulations: A still from a film of the worker strimming at the bottom of Mr Walker’s garden
The contractor turned up in June last year, when he was filmed by the residents clearing it from the riverbank, which is agency land.
Mr Walker plans to move house, but finds himself unable to sell up because of the weed. A law firm specialising in knotweed litigation has been instructed, with Mr Walker as the lead case.
He wants the weed to be treated and a guarantee so that he can move on.
He said: ‘It is causing us a lot of stress. We have been told the value of our home could go down by £175,000 without a proper treatment plan.’
Samantha Towle, of Lincolnshire-based JMP Solicitors, said: ‘It is the claimant’s case that the defendants are not following their own guidelines.’
An Environment Agency spokesman said: ‘Japanese knotweed waste should be disposed of at a licensed landfill site or by controlled burning or burial.
‘All agency staff are required to follow these rules.
‘For legal reasons we cannot comment on this specific allegation.’