Japanese Knotweed purge by National Trust
By Louise Gray, Environment Correspondent
Scenic views that had been lost for decades have returned following the largest clearance in the UK of an invasive foreign weed that is spreading across the country.
Japanese knotweed was introduced into the UK from Asia in the 1840s as an ornamental plant. It grows up to nine feet high and is now the number one on the list of the UK's most invasive plant species.
However in Cornwall the National Trust have managed to clear seven miles of the Kenidjack Valley so that bluebells and wetland plants can return and walkers can enjoy the view once more.
The three year programme used a technique developed by the National Trust which involves injecting the stem of the knotweed with herbicide before clearing the plant from the whole of the course of the stream in the valley.
Simon Ford, Nature Conservation Adviser for the National Trust and the lead on invasive species, said native species can now make a comeback.
"This is a classic example of how invasive plants can literally take over a site.
"It's taken three years of hard work and monitoring to eradicate the majority of the Japanese knotweed and see the beginning of a return of native plant species. The next stage now involves monitoring the site to prevent it re-spreading along the river valley."
It has been estimated that it would cost in excess of £1.5bn to eradicate Japanese knotweed from the UK completely. Other invasive species being causing a problem for the National Trust include parrot's feather, Rhododendron ponticum, Himalayan balsam. New Zealand swamp stonecrop and Laurel.
Mr Ford said the Trust is spending thousands of pounds to clear properties of the foreign plants with the help of volunteers.
"Trying to manage invasive plants is a bit like playing football with moving goalposts as the target keeps changing, as seen with the rise of invasive plants in rivers and lakes in the last decade," he said.
"Add to that the reality of a changing climate and you have a serious problem for the natural world that is dependent on intensive action to control and manage the spread of invasive plants."
Telegraph
22nd May 2009
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