It's rare that plants make headline news, but that's exactly what Japanese knotweed has managed today here in the UK.

There are very few gardeners that have not had their own personal battle with Japanese knotweed and bearing in mind that it can grow up to a meter a month that's no surprise. Its strength means that it can break through concrete and tarmac though and as a result it is estimated that £150 million a year that goes into repairing the damage that it does to roads, pavements and buildings. A large cost like this has meant that people are keen to find a solution to the problem, especially since it manages to grow in its native Japan without this kind of problem.

Japanese knotweed was originally brought to the UK by the Victorians as an ornamental plant, but the problem seems to be that it has no natural predators here. Researchers at CABI have been looking into knotweed's predators back in Japan (both insect and fungi) and have been testing them on over 90 UK plant types to try to find one that would have no harmful effects on other plants. 

It has today been announced by Defra that the go-ahead has been given for an insect called a psyllid (aphalara itadori) to be released in England to fight knotweed. No bigger than a grain of sand, the psyllid lay eggs on the weed and the hatched larvae suck out the sap to kill it. 

The release of the psyllid is the first time that biocontrol has been used in Europe to fight a weed. Initially the insects will be released at a couple of isolated sites where there is a known knotweed problem. Careful monitoring will take place to ensure that the insects only impact on the knotweed and countermeasures are in place in case it is found that this is not the case.

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1 Comment

  1. Japanese Knotweed needs to be treated and disposed of by professionals. Unless you are licensed to do so, it is an offence to dispose of Japanese Knotweed, and treating it with general-purpose weed killer will stunt its growth, but will not eradicate it.
    Professional eradication and disposal is necessary, but can be expensive. Japanese Knotweed Claims will act on your behalf to gain compensation from the party responsible for the spread of the Japanese Knotweed to your property. Japanese Knotweed Claims will act on a ‘no win, no fee’ basis, which means that there is absolutely no cost risk to you.
    Japanese Knotweed Claims will:
    • Win compensation for you, so that you can pay for knotweed removal or if you have already paid for the knotweed to be removed or treated we will recover the cost of the treatment/removal.
    • Put you in contact with professionals who can perform this service.
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    For more information, please visit, email us at, or call us on 0203 151 5205.

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