The Garden Community for Garden Lovers

Is it the end for Japanese knotweed ?


By derekm


Following successful trials around the UK, Japanese knotweed could finally have a natural predator.
Aphalara itadori, is a psyllid, { plant louse } measuring a couple of millimetres has been subject to a controlled release, at test sites around the UK, scientists at the agricultural research organisation
C A B I, says it could be the answer to gardeners prayers.
Tests have shown that the psyllid does eat knotweed, but not closely related plants such as Rhubarb and Dock, and that it has been able to survive the winter in the UK.
The challenge now, is to get it to establish in the natural environment, which isn’t easy, writes one of the researchers, Kate Constantine, in the ecologist.
apart from establishment, it takes time for a new species, to build up large enough population, to have any significant effect on the target plant, and to persist. This is why biological control projects, often take years to show any effect.
If approved, it will be only the second time that a pathogen has been approved for release against a weed in the EU. This summer, a rust fungus was released into the wild, to control the highly invasive Himalayan balsam plant.
you have to be very careful with projects such as these, that the ‘cure’ doesn’t become a bigger problem than the target, an example of which is when Australia introduced cane toads to combat the native grey backed cane beetle, and frenchi beetles, which were damaging sugar cane crops, the toads quickly became more of a problem, than the insects they were intended to control ever were.
At least a solution to the problem is in sight, Derek.

More blog posts by derekm

Previous post: Green thing

Next post: Happy new year



Hope it works - makes me nervous all the same. Trials don't necessarily cover all possibilities do they?

17 Nov, 2014


I feel the same as you Stera. I hope they get it right. Could be a really good thing....maybe!

17 Nov, 2014


It makes me nervous too. We have both, Japanese knotweed and Himalayan balsam . I can control the H. balsam in our place but not the Fallopia japonica. Very invasive. Sometimes one has to wonder what happens after all the knotweed is gone and the psyllid will try to survive. Then what?

18 Nov, 2014


That's it Klahanie.....perhaps they will control it rather than wipe it out altogether...if that's possible with that weed!

18 Nov, 2014


Hi, thanks for the comments, with which I agree, I think the money that this must have cost, would have been better spent, on trying to find an effective weedkiller, that wouldn't damage the environment, that really would be something useful, Derek.

18 Nov, 2014


Yes, too true!

18 Nov, 2014


It was on the news today that if householders don't take steps to control it they face fines and even 'asbos'. though it may lead to more illegal dumping of it.

My daughter was in a rented house that she and the other girls were responsible for keeping the garden tidy. when I went to visit I identified Jkw and she immediately contacted the letting agents who said no it wasn't. Well she challenged them and won and was commended by the council for not caving in. The landlord had a substantial fine and when they had it cleared it had caused structural damage to his property. Previous tenants had cut it down and chucked it over the fence into the waste ground around the electricity transformer for the area. That is also under clearance.

I know the work on this plant biological control has been done very thoroughly and I have a lot of hope for this method.

19 Nov, 2014


That's good to know SBG. And congratulations to your daughter - obviously been trained in a good household, lol!

19 Nov, 2014


Interesting blog ...

20 Nov, 2014


Hi everyone, thank you for your comments, Sbg, I did think of you when I wrote this, and wondered if it could have anything to do with the work that you do, Derek.

20 Nov, 2014


No not at that end of the 'trade' though I am active in recording various pests in the area where I live.

I just amazes me how when we joined the EU so many phytosanitary/biohazard controls just went out of the window.

I never send plant material out of the uk and have only unwittingly received foreign plant material. I am a suspicious old bat :o)

22 Nov, 2014


:-):-):-):-):-):-):-) Derek.

22 Nov, 2014

Add a comment

Recent posts by derekm

Members who like this blog

  • Gardening with friends since
    29 Mar, 2012

  • Gardening with friends since
    25 Feb, 2011

  • Gardening with friends since
    14 Aug, 2008