Acer....root rot?

Discussion in 'Pests, Diseases and Cures' started by totallyconfused, Oct 20, 2025.

  1. totallyconfused

    totallyconfused Apprentice Gardener

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    Hi,

    My parents have an Acer tree, approx 20 years old.

    It has developed leaf wilt and black discoloration at the base of the trunk. Pictures attached.

    Is this root rot? Can anything be done to save it?

    Many thanks.
     

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  2. Pete8

    Pete8 Total Gardener

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    Do any of the branches have bruise like marks on them?
    Something like this -
    upload_2025-10-20_15-26-33.png

    upload_2025-10-20_15-27-12.png

    The pics above show verticillium wilt, which is not treatable and will spoil the shape of the tree, but not necessarily kill it.

    I have an acer with it.
     
  3. Spruce

    Spruce Glad to be back .....

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    Hi

    Intresting post , looks like a black mould , October the leaves are about to fall off , have they died off over the summer ?
     
  4. totallyconfused

    totallyconfused Apprentice Gardener

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    Hi,

    Thanks a lot for your replies Pete8 and Spruce much appreciated.

    Pete8, I had a look at the rest of the tree and no sign of any of the marks/bruising you showed in your pictures.

    Spruce, no leaf loss over the summer. The wilting only seemed to occur on one large branch. Not the whole tree.

    If it is just black black mould on the trunk...is there a way to treat this?

    Thanks.
     
  5. pete

    pete Growing a bit of this and a bit of that....

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    Have you tried washing it off, it almost looks like just a black mould growing on the bark.
    Have a go with a broom or scrubbing brush.
     
  6. Pete8

    Pete8 Total Gardener

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    The tree has probably leaked some sap and moulds have moved in and turned it black.
    It'll probably come off with a bucket of water and a stiff brush.

    Maybe the tree was stressed due to the dry conditions this year.
    I lost one of mine completely
     
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    • Spruce

      Spruce Glad to be back .....

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      Hi

      my acers occasionally have a odd branch die back I trace back to the main stem and remove .

      use a sponge and washing up liquid and try and wash off but don’t go crazy rubbing it off try not to damage the bark.

      I agree with the hot dry summer we have had .

      wait for all the leaves drop off and remove from the area, I would give a mulch and keep a space free around the trunk. A feed in the spring will give it a xtra boost.
      Keep us updated if you can remove the black marks or not

      any chance of a closer photo ?


      Spruce
       
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      • Spruce

        Spruce Glad to be back .....

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        *update*

        I just spoke with my mate who is a tree surgeon, he thinks it could be;

        Sooty bark disease (cryptosroma corticale)


        Majority of the time it’s cause is too dry at the roots , and typical of our hot summer we have just had ..

        He said next year will need TLC or you may lose it

        Spruce
         
      • fairygirl

        fairygirl Total Gardener

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        I'd agree that problems with Acers are more likely to be caused by dry conditions rather than wet. They wouldn't grow like weeds up here if they were bothered by wet conditions. I'ven ever had problems with Acers, but I appreciate that they can be trickier in some places.
        Obviously, the soil they're growing in is always a factor - ie a waterlogged site wouldn't be good for them just as a consistently dry one isn't.
        There's always going to be other factors, such as physical damage, causing a problem, but all you can really do is check that it's not drying out next year, keep an eye on those blackened areas, and hope that it thrives again.
         
      • totallyconfused

        totallyconfused Apprentice Gardener

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        Hi,

        Will try washing down with soapy water. It can't do any harm.

        However, if it is sooty bark disease then I guess that won't help. It's a shame as the tree came from Wilko's, cost a pound 20 years ago. Has been very healthy up untill now.

        I have cut off the wilting branch, will leave to spring and see if tree comes back. Will watch the black bits and see if it spreads

        I guess it has two chances, it either survives, or it doesn't.:frown:

        Thanks for all your help. Much appreciated.

        Regards.
         
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