SCOTTISH house sales are being hit by an invasion of foreign plants.
Japanese knotweed, which can damage building and crack concrete, is increasingly appearing in Home Reports compiled by sellers.
And several major mortgage providers are refusing mortgages if they deem the “invasive species” to be a problem.
Eradicating the plant can cost homeowners thousands of pounds.
Dave Knott, head of the Live Collections at the Royal Botanic Garden in Edinburgh said: “It’s able to punch up through concrete so it can damage the foundations of your house.
“The problem’s been bubbling away for a number of years but now it’s becoming increasingly difficult to control.”
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He said that the knotweed was particularly difficult to eradicate completely.
“It’s hard to control with chemicals and that’s because it has such an extensive root system,” he said.
“The problem with knotweed is that if you dig it up but don’t dispose of it properly or desiccate the roots, it can survive from tiny, tiny bits of the roots.
“Then it just moulders away, like a ticking time bomb for the future.
“It bight do nothing for 10 or 20 years but suddenly – bang – it’s a major problem again.”
Householder Tommy Muirhead had never heard of the plant until he came to sell up.
Tommy, from Muirhead in Lanarkshire, was told the knotweed encroaching on his garden could prove problematic.
He said: “The house belonged to my son. When he bought it seven years ago he had no problems getting a mortgage.
“But the valuator noticed it straight away.
“It wasn’t until I started reading about Japanese knotweed on the internet that I realised how serious it could be.”
Tommy said a number of his neighbours simply cut down or pulled out the plant, which could make problems worse.
A spokeswoman for mortgage lender Santander confirmed that they would be more reluctant to provide funding for a home plagued by the plant.
She said: “Due to the invasive and destructive nature of Japanese knotweed, if it is found in close proximity to the property we would assess whether or not a mortgage could be accepted.
“If the surveyor’s report shows evidence that the weed threatens the structure of a building then a mortgage application would be refused.”
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Such is the problem posed by the plant, a number of specialist businesses dedicated to rooting out the invader have sprung up.
The firms use methods such as chemicals and incineration to get rid of the plant.
Andrew Ferguson, of Wise Knotweed, said: “We set the business up last year after our parent company received repeated requests from chartered surveyor companies.
“It spreads so easily – just a fingernail amount picked up by a car tyre is enough.”
Japanese knotweed was introduced to the UK by the Victorians as an ornamental plant, but it soon escaped from gardens and began spread throughout the UK.
Under the Wildlife and Countryside Act, it is illegal to plant Japanese Knotweed in Britain.
Over £150million is spent annually on controlling knotweed and last year small insects called psylids, which are a natural predator of the knotweed, was introduced to the UK try and curb its rampant growth,.
