Agricultural and environment advisor Andrew Casebow at Moulin Huet with Japanese knotweed, also know as Donkey Rhubarb. (Picture by Daniel Guerin, 0592294)

THE most invasive plant in Britain is threatening to smother the island. Japanese knotweed, or donkey rhubarb, was introduced to Britain from the Far East as an ornamental plant in 1825. It is currently found on more than 100 sites in Guernsey and is spreading quickly.

‘It can grow from just a single node and if someone cuts it and doesn’t dispose of it properly it grows again,’ said States agricultural and environment advisor Andrew Casebow.

The plant has enormously strong and deep roots which can penetrate concrete and go through walls. Japanese knotweed is not listed on the noxious weed ordinance as it flowers but does not re-seed. Mr Casebow said that the weed could be killed by cutting it back and injecting liquid into the hollow stems.