Japanese knotweed (IMAGE) Swansea University Caption Japanese knotweed growing on a bank. The invasive species has been calculated to cost more than £165 million to manage every year in the UK alone Credit Swansea University Usage Restrictions Credit must be given to the creator. Only noncommercial uses of the work are permitted. No derivatives or adaptations of the work are permitted. License CC BY-NC-ND Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.