9th August 1850. Noxious Knotweed.
Japanese Knotweed is classed as controlled waste under the 1990 Environment Protection Act: the Environmental Agency has described the plant as, ‘indisputably the UK’s most aggressive, destructive and invasive’.
This dreaded Knotweed was first introduced to Britain in the 1840.s by a Dutch doctor and set to arrive Today in 1850, at Kew Gardens, the Horticultural Headquarters, as Plant No. 34, in a box of Chinese and Japanese plants.
With its hollow canes and heart-shaped leaves, on bowing stems, Fallopia japonica was soon being planted to complement the shrubberies and carpet bedding, beloved by wealthy Victorians. Farmers used it for cattle feed.
Pictures below show plants which could be mistaken for the Japanese Knotweed, mainly due to leaf shape, but as the Author knows, can be controlled in the garden.
The famous gardener William Robinson in 1898 commented that the Knotweed was, ‘springing up everywhere’, and as another horticultural guru Gertrude Jeckyll said: ‘we ought not to forget the quick growing ways of the great Japanese Knotweed which grows fast and tall’. She thought it was ideal ‘for flanking woodland walks’. So when it ran amok and demolished garden walls, doubts crept in. (1)
The deadly Knotweed was particularly reported, according to Cardiff Museum, in the wild, at Maesteg in south Wales, being noted in the flora of 1886, as being especially abundant on cinder tips. Soon it was colonizing every corner of the Principality and still does.
This is not surprising as the plant originally came from volcanic fumeroles and ash from near Nagasaki, where it thrived amongst the poisonous gases, spreading by underground stem rhizomes surviving on the limited nutrients.
However in Japan there are 186 bugs to contain its growth, along with 40 fungi: here it is predator free, though efforts are being made to use biological control.
Luckily the plants don’t seed, but still spread at a rate of 4 yards a week, reaching depths of 3 feet and will regrow if the tiniest piece is left. The plant is reckoned to cost the nation well over £200m a year in control, and depreciation of property value, as it is capable of breaking through any crack in asphalt and walls.
Successive Governments have admitted defeat on the problem of Japanese Knotweed as the cost of elimination would be prohibitive and any destructive action relies on local effort and control which needs to be done on an industrial scale by experts.
(1) Homes and Gardens 1900.
Alamy.com.Pic of Cornwall.
Daily Telegraph Magazine. 17.9.2016. Sally Williams.
thetelegraph.co.uk. Eleanor Doughty 28.7.2015.Article.