Mark Fennell1, Lois Child2 and Max Wade1
1AECOM, Wellbrook Court, Girton, Cambridge, CB3 0DA, United Kingdom
2Loughborough University, Loughborough, LE11 3TU, United Kingdom
In the United Kingdom, Reynoutria japonica (Japanese knotweed) is regarded as such a threat to property that there have been a number of cases where vendors are unable to obtain a mortgage to purchase a property on which the plant is growing, properties have experienced diminution in value if they have R. japonica growing on them, and land owners have taken legal action against a neighbouring land owner who has R. japonica on his/her land. This situation is unique in Europe although there are indications that the Republic of Ireland may follow the same way. The phases in the history of R. japonica in the United Kingdom since 1981, which account for the mythology that has grown up around the plant and its apparent impact on built structures, are described. These are the enactment of legislation, the development of an industry around R. japonica management, the impact of the press and media, the formation of a trade association to bring order to the management of the plant, landmark legal cases, and recent research into the impact of R. japonica on buildings and a Parliamentary inquiry. An analysis is presented of the factors that interacted to allow this state of affairs to happen and the key role of evidence based decision making in invasive species management. A comparison is made with other countries in Europe and the United States of America and consideration is given to whether a similar situation might occur elsewhere for R. japonica or other invasive non-native plants.