Maps of Ireland and the UK showing the progress of of Japanese Knotweed from 1940 to 1980 to 2016. This means the value of thousands of homes have been destroyed because mortgage lenders are making it impossible for some homeowners to sell their properties. Exposed: The Japanese Knotweed Heatmap, offers an interactive online heatmap of Japanese knotweed sightings across the UK. Dan Casey’s photograph of the infested site beside Castleisland Rugby Club is typical of so many sites in the area. This foundation killer is stalking its way across Britain terrorising its victims as it makes it way from cities to the countryside, from populated areas to isolated woodlands leaving a trail of destruction in its wake. ©Photograph: John Reidy. Citation: National Biodiversity Data Centre, Ireland, Japanese Knotweed (Fallopia japonica), image, accessed 24 November 2020,