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Walnut tree problems

Last post 01-07-2010 12:51 AM by Beetle. 9 replies.

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  • 27/06/2010 08:18 PM
    • lottie
    • essex
    • 04 Apr 2009
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    Can anyone advise - we think our 50yr old walnut tree is dying! It produced quite a lot of very small leaves this spring but now they are all falling off in the hot weather. Last year the leaf canopy was reduced noticeably but not as bad as this year.  Is it lack of water/a walnut tree disease/honey fungus? I took some of the small rather yellowish leaves to Hyde Hall yesterday but they didn't know what it was. The tree has  been healthy and vigorous for the 35 years we've lived in the house. we have had it shaped twice now to keep it to a reasonable size for a suburban garden - the last time was in 2005,

  • 27/06/2010 10:29 PM
    Top 25 Contributor
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     By Juglans, welcome to the forums Lottie!

    Trees can die for all sorts of reasons after they've had big bits chopped off them. That may not even be the cause. 

    Making small leaves is a pretty sure sign that something is very not good, but it doesn't point to any one culprit.

    Photos of the top and base of the tree could help...

    Ed

    www.ashridgetrees.co.uk
  • 28/06/2010 10:22 AM
    • lottie
    • essex
    • 04 Apr 2009
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    HI Ed

    Thanks for your message about the tree. I have taken some photos as you suggested but can't see how to send them!

    Lottie

  • 28/06/2010 03:05 PM
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    Alas, I fear root disease is to balme here, especially honey fungus to which common walnuts are rather suceptible - the only remedy I fear will be the chainsaw. Be sure to get the roots out before replanting.  Try and source a walnut grafted onto balck walnut rootstock - the black walnut is resistant to honey fungus.

     

    Boggy

    Beware the bat-eared bogweevil
  • 28/06/2010 10:44 PM
    • Beetle
    • woking
    • 03 Jun 2009
    • 97
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    Hmmmm, well Boggy - qualified opinion may disagree with your interpretation - the  Pathology Lab at Wisley states that most perennials could be susceptible to one species or other of honey fungus. Whilst the advisory service at Wisley does not appear to have confirmed a case of Armillaria sp in Juglans nigra in the last decade or so this does not imply that J. nigra is immune from its ravages.

    Probably more accurate to say that there is little evidence to support susceptibility rather than confirming immunity. Science should be the way forward here not hearsay or anecdote.

    Beetling ahead....maybe.........?
  • 29/06/2010 08:03 AM
    • lottie
    • essex
    • 04 Apr 2009
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    Well since my last post we've taken a look at what is under the bark atthe base of the trunk. The wood is damp and rotting with white stuff. It smells like mushrooms. So some sort of fungus - but how do I know if it honey fungus???

    Lottie

  • 29/06/2010 10:18 AM
    • dimitri
    • Devon
    • 14 Jan 2010
    • 158
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    Lottie, in view of your last post this definitely sounds like honey fungus.  A characteristic symptom is exactly as you describe:  sheets of white fungus mycelium between bark and wood, smelling of mushrooms.

     

    If you dig down to look at the main roots, at least some of them will be affected in the same way.  The key feature is that honey fungus grows in and kills roots by forcing its way between bark and wood.  After killing the root, it then feeds on the decomposing wood.   When the advancing infection reaches the base of the tree it starts to encircle it and at this point you start to see symptoms above ground, just as you describe.  It is too late by this stage to save the tree.

     

    Quote from Strouts, R.G. and Winter, T.G. (2000) Diagnosis of ill health in trees.  2nd ed. The Stationery Office (P.39):

     

    "English or persian walnut,  Juglans regia, is particularly susceptible to killing by honey fungus (Armillaria), whereas observations and experimentation indicate that J. hindsii and J. nigra are probably immune."

     

    Honey fungus spreads through the soil by means of rhizomorphs, black threads which can then infect new roots on contact.  However, the rhizomorphs can only live when they are attached to the dead roots they are feeding on, they do not live independently in the soil.  To deal with an infection you have to do two things.  Firstly, excavate all the affected roots and burn them.  Secondly, try and trace where the infection came from, which is almost certainly another old stump in the near vicinity.  If you can be sure you have got rid of all the roots and stumps that might be a source of re-infection, you will be safe to replant.  However, it would still be safest to replant outside the root zone of the old tree, because many trees do not thrive if replanted directly where one was previously growing.

     

    Juglans nigra would be a safer bet than J. regia in view of its strong resistance to infection.  It is stated to have edible nuts, but I'll leave others to comment on how good they are, in my experience it is grown primarily for its timber.

  • 29/06/2010 11:42 AM
    • lottie
    • essex
    • 04 Apr 2009
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    Thanks Dimitri

    We have had a quote for removal of the tree - just under £400 which includes £40 for grinding out the root ball. I don't know whether that will be enough to remove it all.  I was hoping it wasn't honey fungus - as the tree guy din't think it was.

     

  • 29/06/2010 02:21 PM
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    Ideally see if you can get the contrractors to get out some root too as this will help limit spread toother trees, but of course it may be difficult inthe confines of a small space.

     

    Boggy

    Beware the bat-eared bogweevil
  • 01/07/2010 12:51 AM
    • Beetle
    • woking
    • 03 Jun 2009
    • 97
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    Well, grinding out the root will only prevent spread of fungal material if it is all removed - excessive grinding will cause lessions / root damage to neighbouring trees & shrubs potentially increasing probability of further root deterioration. This is not the end of the world - remember that RHS Wisley is riddled with honey fungus in all its guises as well as many other fungal problems - just like most gardens! If you are going to have the 'stump' ground out it is well to ensure that it is ALL ground out (not just the top 10cms or so) and that all substantial roots are also removed. Waste material should ideally be moved to a composting area and incorporated/broken down with loads of leaf/green waste. Otherwise - plant less susceptible speicies and try & attain optimal health by promoting good growing conditions!!!!Confused

    if nothing else - when the 'grinder' has finished their business - you should be able to dig to at least a forks depth without undue problems!!!!!Smile

    Beetling ahead....maybe.........?