Wood sun injuries.

Discussion in 'Maples' started by opusoculi, Mar 25, 2021.

  1. opusoculi

    opusoculi Well-Known Member

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    Hy ! Good season now.

    What is the appearence of wood burns by the sun, how they looks like ?

    1- Here are photos of 2 dissectum trees -upper side of main branches indeed-.
    Are those grey spots typical of wood sun injuries ?

    2- Does such sun injuries are able to recover ?
    Have you ever observed such grey spots becoming green again; i mean, do new fabrics replace them ?

    Do you think it is only a superficial state , bark guetting with sun an oldest appearence ?
     

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    Last edited: Mar 25, 2021
  2. Acerholic

    Acerholic Paragon of Plants Forums Moderator VCBF Cherry Scout Maple Society

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    I think you have anserwerd the question yourself Pierre, IMO it is all perfectly normal and the appearance of age only. The bark looks very healthy indeed.
     
  3. opusoculi

    opusoculi Well-Known Member

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    We have to wait some other analyst with more knowledges.​
     
  4. 0soyoung

    0soyoung Well-Known Member

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    Like @Acerholic said, the grey coloration is just the formation of mature bark. It is not damage. Green bark (or red in the case of Sangokaku, yellow with Bihu) is young or immature bark. Each season the cork cambium generates a few layers of dead cork cells. Over time these accumulate and occludes seeing the green bark. Instead we see an opaque grey color. It progresses more rapidly on the upper surfaces of maple stems and has little or nothing to do with sun exposure. Exogenous ethylene can radically accelerate the growth of bark in complete darkness, for instance.

    Again, as @Acerholic said, what you are seeing is a normal aging process.
     
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  5. Nik

    Nik Rising Contributor

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    With my very limited experience with maples I agree with the previous replies. I see this too and the plants are perfectly healthy. Nothing to worry about.
    (Although in previous threads in this forum, about bark issues, there were very confusing posts about something called “tight bark”, I still don’t know what that means...)
     
  6. 0soyoung

    0soyoung Well-Known Member

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    I agree about not liking the term 'tight bark'. The underlying phenomenon, though, is that the cambium (the layer of cells between the wood and bark which affect radial growth / thickening) dies by desiccation.

    Most commonly it happens in winter but may also happen because of a lack of available water during the growing season. In this latter circumstance, the overlying bark will oftentimes discolor and may even blacken and become 'punky'. During winter, though, the cambium is not much more than one cell thick and its death usually goes unnoticed until growth begins along the margins of the dead area in the following growing season or next after that. As this happens, the stem is also thickening, so the dead bark gets lifted off the wood (hence, I suppose, the sense of 'tight bark'). At the end of this first growing season after the damage or the next, the dead bark will tend to flake off (if one hasn't already poked through it with a curious finger) and one will begin to see the 'lip' of new growth beginning to close over the 'wound'. These 'winter wounds' do tend to be on the sun-exposed surfaces, but it looks like this which has occured on a tree that already had 'mature' bark.
     
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  7. opusoculi

    opusoculi Well-Known Member

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    Detailed and clearly explained. Many thanks Osoyoung. It is not the first time i appreciate your writing.
    Let me ask you a few questions.

    1- Is there any other case of sun scald during the growing season ?
    On those pics, do you think injuries are due to extreme heat or extreme lightning ?
    (A callus layer had close over entirely very quickly).
    Note: there are other little injuries (1 cm each) inside 2 Apple trees, inside is not exposed to sun. And two different Acer trees are affected ...

    2- Or, is that possible due to accidental friction ?
    But what about those witch are inside ...

    2- If those vertical injuries are not due to hot temperatures or lightning, nor accidental friction, can we suspect a disease symptom ?
    For instance, fusarium (FHB ?).
     

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    Last edited: Mar 25, 2021
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  8. 0soyoung

    0soyoung Well-Known Member

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    • YES there are other things, friction wounds (rubbing of crossing stems) scratches (animals) and bark tears (human errors associated with cutting tool nicks, or collisions with motorized devices, blunt tools, for example). And
    • YES, disease is a possibility though recovery tends to not happen until the pathogen has been eliminated.
    Local death of the cambium is common to all and then regrowth of tissues over the damaged area making the characteristic 'lips' and/or raised/tight bark that readily falls away.​
     
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  9. opusoculi

    opusoculi Well-Known Member

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    Many thanks for you helpfull contribution.
    « local death of cambium » is a very good expression.

    About local death of cambium, I think there is a difference between bacterial and cryptogamic disease.
    I agree, bacterial disease recover when the pathogen has been eliminated.
    In case of cryptogamic root disease such as verticillium and fusarium, sometimes local death cambium are symptoms of the first suffers of those diseases.

    Arrived there, we are in pathology, we have no way to exactly know.
    We will see next what occurs and do post photos in the future.
     
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  10. AlainK

    AlainK Generous Contributor Forums Moderator Maple Society 10 Years

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    Right, it's more of a matter of trial and error because we have no possibility to have each of the damage our trees suffer being thouroughly examined by a laboratory to exactly know where the problem comes from, and what kind of treatment should be applied - if any.
     
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