White powder on my weeping cherry??

Discussion in 'HortForum' started by The green hornet, Jun 23, 2010.

  1. The green hornet

    The green hornet Member

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    Lots of branches of my weeping cherry tree are covered with powdery substance that seems to kill the smaller branches. Also, quite a few leaves are turning brown and falling off. What to do? Thanks in advance for the help. I live in Massachusetts.
     

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  2. Frog

    Frog Rising Contributor Forums Moderator 10 Years

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    Hi TGH,

    Can you take a closer look at it with a magnifying glass? Do you see any structure to it, or is it just powdery at that magnification? Do you see any tiny black spots embedded in it? Also can you tell if it starts at the buds/leaves and spreads to twigs and branches, or if there is any apparent spread pattern? Are there spots or any structures/patterns on the leaves before they turn completely brown?

    At first it looked like lichen on bark, but when I looked at your photo at greater mag, I thought it might be a powdery mildew. Not to get your hopes up, I have no expertise in mildews & friends, but I am now the proud owner of "The Compendium of Plant Diseases," an older book which has been interesting and helpful with mildews, rusts, smuts and other microfungi that cause trouble for plants.

    - frog
     
  3. The green hornet

    The green hornet Member

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    Thanks for the reply, Frog ( I too am a frog, a human frog from France ). Anyhow, a picture is worth a thousand words as they say. Check these out ( tubes + worms?? ) and let me know what you think.
    Best regards
     

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  4. lorax

    lorax Rising Contributor 10 Years

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    Re: To all gardening detectives, what is this?

    Looks like lichen to me. In which case you don't really need to be concerned about it - lichens don't harm the tree in any way, they're just using it for support.
     
  5. saltcedar

    saltcedar Rising Contributor 10 Years

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  6. Frog

    Frog Rising Contributor Forums Moderator 10 Years

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    When you said that I got all excited hoping this might be a case of Septobasidium fungus using scale insects to suck sap, which I've heard of but never seen. However unfortunately (for me, not for the tree) none of the descriptions of Septobasidium match this appearance.
    -frog
     
  7. saltcedar

    saltcedar Rising Contributor 10 Years

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  8. abro

    abro Member

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    Hi,
    I have a weeping cherry with the same white powdery growth on its trunk and branches. Some of the affected branches have dead leaves and the branches appear to be dying. There are a lot of ants running up and down the branches too.

    I didn't see any clear recommendations on what to do about the problem. Is there some kind of spray or other treatment that I can apply to fend off what I think is the white scale?

    Any help is much appreciated,
    Adam
     
  9. saltcedar

    saltcedar Rising Contributor 10 Years

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    Seems pretty clear to me. What's confusing you?

    "I have suggested a ‘power washing’
    of heavily infested plants during the
    dormant season before budbreak, to clean
    off scale residue and expose crawlers to
    treatment. Some applicators have even
    scrubbed bark of infested specimen trees
    (flowering cherries, e.g.) with a soft brush
    where appropriate.
     Check for presence of the tiny dustlike
    crawlers starting from late April onward. Examine twigs
    carefully for them or wrap infested twigs with double-sided tape to
    trap them as they move or blow around. Tapping branches over a
    white surface can also be used to detect crawlers. We have previously
    reported two generations of this insect here, but Dr. Raupp feels
    there may even be a third as in Maryland. This could easily occur
    especially in warmer years or
    locations. Crawler activity
    could also vary by a week or
    two from one year to the next
    and in different areas around
    Long Island, and delayed
    especially in cooler areas
    influenced by the ocean. Treat
    when crawlers are numerous;
    horticultural oil at summer rates
    is one option."
     
  10. lorax

    lorax Rising Contributor 10 Years

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    Sprays are pretty much the only resort here, since the infestation is so heavy. Since we're into summer, I'd be looking at the summer oils - Neem is fairly good (and less harmful to the environment.)
     
  11. abro

    abro Member

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    Thanks for the advice. I have no idea what horticultural oils are, but I will look up Neem and see if I can get some to spray on the tree. Is there a website or vendor you would recommend for this?

    I already took the step of blasting as much of the white stuff off as possible with the sprayer attached to my hose.

    Adam
     
  12. lorax

    lorax Rising Contributor 10 Years

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    I have absolutely no idea for the US - down here, I can buy Neem oil at my local garden center. Check your local nurseries and greenhouses - it's a fairly common product.
     
  13. saltcedar

    saltcedar Rising Contributor 10 Years

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  14. abro

    abro Member

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    Thank you both so much for your help. I'll see if I can find it locally else I'll order from one of the online sources. Hopefully the poor tree will bounce back.
     

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