According to the London Evening Standard of 24 June 2013:

‘Thousands of house sales in London are being hit by the spread of Japanese knotweed [Fallopia japonica] as lenders refuse to offer mortgages for properties affected by the scourge, and expert claimed today.’ Charles Carter, who runs Knotweed Management, a consultancy which advises homeowners and others on knotweed elimination, has accused banks and building societies of ‘going over the top’. Although this news is perhaps not quite folklore, it is apparent that much of the fear of Japanese knotweed is increasingly irrational, with people who have no real knowledge of the plant being unwilling to contemplate lending money to potential buyers of any property on which it grows.

See also an article, ‘How menacing march of Japanese knotweed is uprooting home sales’ in The Times, 6 July 2013.

Images: upper, Brentford, London Borough of Hounslow, August 2014; lower, notice, Cycle Network track 32 between Bodmin and Bodmin Parkway Station, April 2014.

Updated 22 August 2014.