Help identifying (and fixing) white fungus on Japanese Acer

Discussion in 'Maples' started by thierry, May 20, 2010.

  1. thierry

    thierry Member

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    Hello,

    This is my first post. I've searched the web a lot to help identify a problem on my Japanese Acer, but no luck.

    From what I've gathered, it could be a fungus. There are lots of little 10mm (under half an inch) diameter blobs, they are white, cotton-like, with a brown "hat". They grow everywhere under the trunk and branches. There's nothing on the top side of the trunk/branches. The leaves look happy.

    I've moved into this house 3 years ago and there's been no problem. I don't know how old the tree is or what precise species it is. I've never watered it. I live in London, UK, natural rain seems to be enough. The tree is against a 2m (6ft) high north facing fence which protected it from the sun. It therefore doesn't get scorched by the sun.

    I've read that potentially there are too many branches at the top and that could restrict the air flow. I've never trimmed the top branches. I've also added 2 months ago a large wooden planter just next to the Acer which could also restrict the air flow. Finally, the soil around the Acer was covered with fabric and lots of white gravel laid around the whole area.

    See the picture. Any idea what this is? And how to remedy the situation?

    Many thanks
    Thierry
     

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  2. maf

    maf Well-Known Member Maple Society

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    Hi Thierry, it is not a fungus but a scale insect, Pulvinaria regalis or Horse Chestnut Scale. Common in UK towns and cities on some species of trees including maples. At this time of year the adult female lay their eggs on the bark protected by their own body and the white fluffy substance seen in the picture.

    They may slightly weaken the trees but do not do major damage, apart from look ugly. I find that rubbing these pests off the bark, either by hand or with a brush, is an effective if time consuming method of control. It interupts the life-cycle and numbers seem reduced in following years. Systemic insecticides might work against them but have not tried this myself.
     
  3. thierry

    thierry Member

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    Many thanks!

    In parallel, my wife has also found that they were scale insects and her work colleague advice:
    "You have to spray the tree with a mixture of water and washing up liquid and then spray them with Sybol or a systemic insecticide (the washing up liquid loosens the insects. Apparently they suck the sap so will eventually kill the tree! They lay their eggs over the winter so it won't be anything to do with the planter apparently. In the winter we need to 'wash' it again to get rid of any new eggs."

    Here's another link about it:
    http://www.gardenersworld.com/how-to/problem-solving/garden-pests-scale-insect/

    Many thanks.
    I realise this might have been posted on the "Japanese Maple Bark Related Issues" thread.

    Thierry
     
  4. jessetc

    jessetc Member

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    thanks for the info!
     

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