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Japanese knotweed could cost you thousands

3 minute read
Japanese knotweed could cost you thousands

Published by the Eagle Radio News Team at 7:00am 2nd October 2016. (Updated at 11:19am 3rd October 2016)

The people of Surrey and Hampshire are being urged to be on the lookout for the UK’s most destructive invasive plant.

The Japanese knotweed can crack roads, damage buildings and even bring down the value of your house.

The plant costs the UK economy £166 million a year in removal expenses and property devaluations.

Environet, based in Send, is one of the UK’s leading and longest established knotweed eradication specialists.

Managing director of the organisation, Nic Seal, said: “We’ve seen situations where it’s coming up through floors of properties, I’ve seen it growing in cavity walls of buildings, pushing the walls apart.

“We’ve had a few examples where it’s actually come up and penetrated through rooves. It spreads very, very easily – grows very, very fast and it’s incredibly difficult to kill.”

Knotweed can be removed by specialists, like Environet, and the sooner it is identified, the better. The roots spread horizontally and can go up to 2 metres deep.

To kill it quickly, this requires full excavation of the roots, which can cost over £10,000, even for a domestic house.

The cheaper option is to poison it with herbicides. However, this still costs around £2,000, can take up to 5 years of repeated applications, and cannot guarantee that it will not re-emerge years later.

"It spreads very, very easily – grows very, very fast and it’s incredibly difficult to kill.”

In preparation for the London 2012 Olympics, the site for the Olympic Park had to be eradicated of its knotweed infestation. Clearing the 10 acre area cost more than £70 million.

There are plans to attack this plant invasion. The Centre for Agriculture Bioscience International (Cabi), have been searching for an insect that feeds on the knotweed, but importantly, does not attack any plant species native to the UK.

However, Cabi have hit a stumbling block with this method. The chosen agent to attack the knotweed, the Psyllid, is struggling to adjust to life in the UK after leaving its native home.

Dr Richard Shaw, regional coordinator for invasive species at Cabi, said: “It might be because it’s been 140 years under a Japanese summer and then it’s suddenly thrown out in Berkshire in the spring.”

Until a permanent solution is reached, Environet are encouraging people to act fast if they discover any Japanese knotweed.

The organisation also has a free identification service if you send photographic evidence to the Environet website, however they do ask for a donation to charity in return.


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