A bemused builder faced the possibility of prison or a £5,000 fine after Merton Council wrongly reported him for disposing of highly-invasive Japanese knotweed growing on its own land.

Dariusz Bak, 34, who owns Morden building company Terra House, was building an outdoor gym for a client in Melbourne Road in south Wimbledon when he was accused of removing Japanese knotweed from a council-owned footpath which backs onto the property.

He was mixing concrete on the former railway track in November when he said he was confronted by a council officer for working on the path.

The experienced builder who said he knew the dangers of tampering with Japanese knotweed said he told a council officer the plant was growing there.

Wimbledon Times:

Japanese knotweed can be removed by specialists after about six herbicide treatments over a period of three to five years

A few days later Mr Bak was "shocked" when police turned up on his doorstep at 10pm to arrest him on suspicion of disposing of knotweed.

When he told police he had his young children at home, he was allowed to go to Wimbledon Station the following Wednesday where he was arrested.

But when he appeared at Wimbledon Magistrates' Court earlier this month ready to deny any wrongdoing the charge was withdrawn.

Now the owner of the property where Mr Bak was working, Jonathan Boughton, is demanding the police prosecute the council for failing to eradicate the plant on its land.

He said: "Clearly they haven't treated it. As a householder, I'm concerned about Japanese knotweed encroaching on our properties. The council hasn't informed anyone."

Merton Council has been aware of the issue since 1998, when it published a general maintenance plan for Merton Park Green Walks, a path which runs along the former railway track between Merton Park and Tooting.

But a Freedom of Information request has revealed the knotweed on the path has only been treated twice, in the summers of 2011 and 2013.

Properties in Melbourne Road back onto Merton Park Green Walks 

Police can issue a Community Protection Notice or Community Trigger under the anti-social behaviour, crime and policing act 2014 to force owners to treat knotweed.

But a Merton police spokesman said it was not considering taking action against the council because it had a plant management system in place.

A council spokesman said: "It is the view of the council that it is meeting its obligations to discourage the growth of Japanese knotweed and has a planned JK management programme which involves spraying the weed to keep it under control.

"As part of the council programme, we inspect specific council-owned sites across the borough so we can spot any potential growth which we can then remove or contain by spraying."

Merton Council is unable to collect or dispose of knotweed. If you discover the plant on your property, you need to contact a specialist for advice and treatment.

Sam Ward, a specialist knotweed surveyor based in Deer Park Road, Wimbledon , said you will always be within about half a mile of the plant in Merton.

But he said it can always be eradicated, usually over a period of between three to five years with about six applications of herbicide. 

Why does everybody hate Japanese knotweed?

Japanese knotweed is a green-leaf plant with white flowers, first imported as an ornamental plant by the Victorians.

Knotweed can now be found in every six-mile square patch of the UK, official records have shown.

All UK plants are descended from a single female plant It cannot produce seeds but grows a fresh plant from the tiniest fragment of its stem or rhizome.

In Japan it is kept in check by natural biological controls which do not exist in Europe.

The plant can grow as much as 20cm a day and has been dubbed the second biggest worldwide threat to biodiversity.

It can lie dormant for years and then spring back to life. If untreated it can seriously damage foundations and even push its way through concrete.

It can take years to kill with herbicides. It is estimated to cost the UK economy £165m a year.

For more information about knotweed and how to dispose of it, visit the Government's dedicated web page. 

Is Japanese knotweed growing on your Merton property?

Share your experience by calling Louisa on 020 8722 6335, emailing louisa.clarence@london.newsquest.co.uk or tweeting to @LouisaWimbledon.