Powdery substance and scorched leaves - Japanese maple

Discussion in 'Maples' started by Unregistered, Aug 27, 2003.

  1. Hello

    This is a young tree and only a few years old, living in a container.

    It is watered regularly, and I have now placed it in semi-shade, away from any winds, as i assumed that this is why the leaves are scorched.

    There is also a white powdery substance on the trunk, that can be scratched off. I have no idea whether the powder and scorched leaf problem is related.

    Please help a non-gardener, but very fond of my tree.

    Thank you
     
  2. Douglas Justice

    Douglas Justice Active Member UBC Botanical Garden Forums Administrator Forums Moderator VCBF Cherry Scout Maple Society 10 Years

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    Location:
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    Scorching on Japanese maples is extremely common, particularly late in the season. In short, the scorch is caused when evaporative demand from the atmosphere exceeds the ability of the plant to supply moisture to the leaf tips from the roots. Conditions that may cause or contribute to scorching include drying out, excessive salts (from fertilizers or hard water), disease, excessive heat, sustained winds and flooding.

    Some cultivars are particularly sensitive and will scorch basically if looked at sideways. In parts of California, anti-desiccants are sprayed on foliage to reduce water loss and prevent scorching. In the Vancouver area, it seldom becomes necessary to treat Japanese maples in this way. Locally, summer drought is the most common cause of scorch in the landscape; in containers, it is insufficient watering and excessive fertilizer application. (It would be useful to know under what conditions you garden.)

    Japanese maples are most comfortable in woodland surroundings with a cool, moist root run. In containers, heat is a serious problem even in cooler climates. The larger the container, generally the better the conditions (roots are better insulated from heating, cooling and drying out).

    If the white, powdery substance on the stems is a thin, smooth coating, it is probably cuticular wax, a natural substance the plant produces to protect the stem. It is probably better to leave it alone. On the other hand, if the coating is bumpy and not particularly homogeneous, or it moves on its own, it may be something else (possibly an insect).
     
  3. Mary

    Mary Member

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    What disease could cause scorching on leaves? How can I differentiate disease vs evaporative demands vs "quirky tree syndrome" (my verbage)..............? The tree I have is probably 6-10 years old, and I am a new home owner, thus new tree owner.
     
  4. Rima

    Rima Active Member

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    Too much sun! The majority of Japanese maples (especially the lacier ones) should be in light shade or at least filtered (through a larger tree) light, though some can take more sun than othes. The powdery stuff could even be powdery mildew from overwatering (they don't appreciate that either).
     
  5. petauridae

    petauridae Active Member

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    Location:
    Walla Walla Valley, WA, USA
    The powdery stuff could even be hard water deposits...we get that in my area. It usually flakes off really easily and feels like silica because that is what it is!
     

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