Sunday, 26 September 2021
AN invasive and fast-growing weed in the River Thames has spread to Henley.
Floating pennywort, which comes from the Americas, can grow up to 20cm in a day and forms a thick layer that kills flora and fauna by depriving them of oxygen.
The Henley Standard has reported residents of Sonning and Wargrave complaining that the weed was “clogging” the river in the villages and the Environment Agency has begun clearing it from the water.
Now a woman says a stretch of the river outside her home in Wargrave Road, Henley, has a covering of the weed measuring about 15ft x 10ft and she is worried that it could spread further towards the town.
Enid Light, 84, said she returned from more than a month away to discover the plant in an offshoot of the Thames by the block of flats where she lives. There had been no indication of the weed when she left.
Mrs Light said: “When I got back I’d never seen the river in such a state. I’d never heard of pennywort before but I opened the Henley Standard and there was a picture.”
She has reported the infestation to the Environment Agency but doesn’t know when it will be cleared and even contemplated trying to tackle the problem herself.
She said: “I immediately phoned the agency and spoke to three different people. I said I wanted someone to come and see it and for advice on what we should be doing.
“Some of it can be pulled up around the edges but I’m not sure if it’s good for us to do it. I don’t have my dinghy at the moment so I’m not in the position to go out and grab the shoots.
“It worries me. I’ve lived here for 30 years and have never seen anything like this. Now it’s on the Henley reach it will easily be carried down the main stream.”
Last month, former conservation manager Alastair Driver, who lives in Sonning, said more needed to be done to deal with pennywort.
He said clearance teams from the Environment Agency were only removing large clumps of the plant and leaving smaller patches. Prof Driver, who oversaw the eradication of the plant at Reading a decade ago, said the agency should sweep the main watercourse more often and more thoroughly.
The “carpets” of pennywort are too heavy to remove by hand so must be pulled out using mobile cranes then incinerated to ensure they do not reproduce. Every fragment must be destroyed to prevent an infestation from recurring.
Prof Driver also urged the agency to tackle a second infestation at Hennerton backwater, which flows off the Thames near Wargrave.
Floating pennywort has broad, shiny, kidney-shaped leaves with fine roots below the water and thick, fleshy stems and occasional small white flowers.
It was accidentally introduced in the early Nineties by people discarding garden plants and it is a criminal offence to grow it in the wild. It is thought to have spread to the Thames from a lake at the Green Park science estate in south Reading in about 2008.
A spokeswoman for the Environment Agency said: “We have been removing floating pennywort from the Thames during October and November and continue to assess the area for this invasive species.
“Members of the public can report invasive plants to our incident hotline, 0800 807060.”
04 December 2017
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