Japanese Knotweed

October 2013

Japanese Knotweed is an invasive root system and reproduces from its creeping underground stems.  It can damage concrete foundations, buildings, road tarmac, paving, retaining walls and flood defences.  It can also reduce the capacity of channels to carry water in flood defences.   It grows at an alarmingly fast rate.   It is listed by the World Conservation Union as one of the world’s 100 worse invasive species.

It is a large herbaceous perennial plant native to Eastern Asia in Japan, China and Korea.  In North America and Europe it has been classified as an invasive species.  It is established in the wild in the UK and causes headaches for developers and landowners alike.

To identify Japanese Knotweed it has hollow stems with distinct raised notes similar to bamboo .  The maximum growing height is 3-4 meters each growing season.  The leaves are broad oval with truncated base with small cream or white flowers in late summer and early autumn.

Landowners are not legally obliged to remove Japanese knotweed unless it is causing a problem to a neighbouring property however, it is an offence under the Wildlife and Countryside Act 1981  to plant or cause it to grow in the wild and any disposal of the plant requires disposal at a licensed landfill site.

Owing to its hardy and invasive nature it is of course hard to and expensive to remove and it is stated a national eradication programme would be prohibitively expensive at £1.56 billion and is not a one off treatment but one that needs to be repeated every four to five years.

For more information, please contact Sharon Whiting on 01296 318500.