Japanese Knotweed (1 Viewer)

John Cantelo

Well-known member

Julie50

Mostly in the Midlands :)
United Kingdom
Surely the organism/disease is species specific has been said too many times before.................
 

Xenospiza

Distracted
In an effort to control Japanese Knotweed, the Dutch will release of 5000 Japanese Leaf Fleas.

Can anyone think what could possibly go wrong, I mean, it's not like there's a history of disastrous releases is it..........

https://www.theguardian.com/world/2...ases-leaf-fleas-halt-japanese-knotweed-growth
There are also good examples, such as the weevils released in the USA to fight purple loosestrife. There are no close relatives of Japanese knotweed which aren't invasives as well (e.g. Giant knotweed).
 

Julie50

Mostly in the Midlands :)
United Kingdom
Interesting article. I could only see the Abstract for the small scale trials, Shaw 2003. It states the trials were due to start in 2010 and finish in 2015. The last amendment to the main article was 2019, but there was no update I could see on the UK trials. Does anyone know the results of the trials in the UK? I am assuming they were positive or the Dutch would not be having a go!

I’m going to have a look on the inter webs! I am interested because it and the balsam are quite prevalent in the West Midlands!
 
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dantheman

Bah humbug
I found thisinteresting and helpful, I may have to change my opinion, but am still a bit sceptical!

https://www.cabi.org/japaneseknotweedalliance/frequently-asked-questions/

Interesting that is 10 years ago - surely it would be more widely known or trialled if successful?

Saying that, given the problems with Japanese Knotweed I would expect that a sensible biological control is the only way forward, and as expected, much more rigorous than just 'releasing a load of random critters into the countryside'.
 

Xenospiza

Distracted
There is a PhD thesis available from Imperial College which notes that the first CABI trials had less impact than expected:
https://spiral.imperial.ac.uk/bitstream/10044/1/23232/1/Clewley-GD-2015-PhD-Thesis.pdf

"There were demonstrable impacts of A. itadori herbivory on F. japonica within a single growing season. Nonetheless, there was a discrepancy between the predicted performance from this study and what has been observed at the open field release sites."

Since Japanese (and Giant) knotweed have no native species which can control them, introducing a specific biological control species is necessary to get rid of them...
 
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Julie50

Mostly in the Midlands :)
United Kingdom
If I read it correctly the issue is establishing self-sustaining colonies which are large enough to have an impact.
 

StuartReeves

Local rarity
I heard a piece on the radio about this. If I remember rightly, the leaf fleas that were released in the original trial did not survive well enough in the UK to have much of an impact. The Dutch have gone back to Japan and have obtained fleas from a region with a much closer climate match for the UK/Netherlands so in principle they have a better chance of surviving this time around.
 

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