Japanese Knotweed

Managing Japanese Knotweed is a problem. Get it wrong and you could face a significant increase in development & maintenance costs, end up in court, or a combination of all the above. The rhizome based plant is extremely aggressive, advancing by as much as one metre per year, and exceptionally difficult to contain. The root system including the plant's rhizome based feeding mechanism is capable of defeating any amount of 'treatment'.

Weed control barriers, although widely used, are not always a long-term solution. Government departments are seeking views on the possible release of an insect, a psyllid species Aphalara itadori, as a control for Japanese knotweed, Fallopia japonica. The joint consultation is aimed at all those with an interest in the impact of Japanese knotweed on the natural and built environment, including the horticulture industry, landscape managers and contractors and people interested in the control of invasive species. If approved the release of this organism would be the first use of a non-native insect species to control a plant species in the UK and Europe.

In the UK, there are several organisations plus Wikipedia that provide excellent guidance. This includes management plans, risk assessments and control measures for industrial development.

1. Environment Agency
   • Japanese Knotweed and how to manage it
   • Knotweed Code of Practice
2. DEFRA - Code of Practice plus several papers on the issues (search for knotweed on the Defra site)
3. CABI - a not-for-profit science-based development and information organization. See www.cabi.org/japaneseknotweedalliance for an Information Pack including 'The Natural Control of Japanse Knotweed)
4. Japanese Knotweed on Wikipedia (see 'Control' paragraph for recommendations) - See the 'References' and 'External Links' sections which contain useful information.