Residents are fearing a council will leave them with a Japanese Knotweed problem as a treatment programme designed to kill the invasive plant has left them with roots growing on their land.

People living in Lisbon Drive in Darwen say the council has attempted to treat the Japanese Knotweed growing on Bailey's Field at the back of their homes, where developers, McDermott Homes, plan to build 343 new houses.

Lancashire Telegraph: The Japanese Knotweed is continuing to grow, say residents in Darwen despite BwD council saying they had treated it

However, during the treatment process, which can take a number of years before a site is properly rid of the weed, the invasive species started to spread into the rear gardens of those living on Lisbon Drive.

Nigel Cook, who lives in the area said: "Last week McDermott Homes started the groundworks for the first phase of house building on Bailey's Field.

"Sub-contractors started removing the Japanese Knotweed immediately behind the houses on Lisbon Drive.

Lancashire Telegraph: The Japanese Knotweed is continuing to grow, say residents in Darwen despite BwD council saying they had treated it

"They are then going to transfer it round the corner to near the top of Bailey's Field, towards Roman Road, and bury it there.

"It will be buried in a two metre deep pit and wrapped in a geo-textile membrane so it can't regrow.

"They claim it will be periodically checked and monitored, but the land behind Lisbon Drive where the Knotweed was present will also be lined with a geo-textile membrane, particularly between the boundary of that site and our gardens.

Lancashire Telegraph: The land on which Japanese Knotweed has been growing in Darwen

"The problem is, this membrane will stop the Knotweed roots growing on Bailey's Field but not in our gardens.

"My concern, and that of the Lisbon residents, is that the council is intending to leave the roots on our property, which in effect makes the problem ours."

Photos taken at the site show where contractors have begun lifting what they claim is treated Knotweed and how, according to Mr Cook, some of the fresh growth is being missed.

Growth and development boss at Blackburn with Darwen Council, councillor Phil Riley, said: "I understand the residents' frustration. The process of killing the Japanese Knotweed doesn't happen overnight.

"To me, it sounds like the developers and the sub-contractors are doing the right thing and have the correct approach.

Lancashire Telegraph: The land on which Japanese Knotweed has been growing in Darwen

"I understand the residents will be concerned about the bits that are being left on their properties and I will find out exactly what is happening with that."

This is not the first time residents in Darwen have raised issues about the troublesome plant.

In October 2019 Blackburn with Darwen Council bosses backtracked on their claims that there was ‘categorically no Japanese knotweed’ present on another piece of land earmarked for development.

Residents living close to the Tower View site in Darwen, which had been earmarked for 17 new homes, had written to the council expressing their concerns over the presence of the invasive weed.

Lancashire Telegraph: The land on which Japanese Knotweed has been growing in Darwen

Cllr Riley, said there was none of the plant detected on that particular site, despite it being discovered on other development areas in the town.

He stated: “There’s Japanese knotweed on the adjacent Marsh House site which came to light during the Ellison Fold Way construction and we’ve started a programme of treating it with chemicals that will take approximately three years.

“But I can categorically say there is no Japanese Knotweed on the Tower View site.”

Lancashire Telegraph: The land on which Japanese Knotweed has been growing in Darwen

Alarmed at the council’s denial, resident Nigel Cook wrote directly to Cllr Riley to tell him he had been misinformed.

Cllr Riley looked into the issue and said the Knotweed present on the Tower View site would be treated in line with the treatment of the weed on the Ellison Fold Way development site.