Something black on the branches of my Acer palmatum viridis dissectum

jordystokes

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Didn't have time to take a picture this morning. Sorry. I will describe the best I can and add pictures later.

Tree: Acer palmatum - viridis dissectum. Not a bonsai yet, in a large pot. Has leaf burn from the summer. Leaves are starting to turn to their fall color. As I can tell it is relatively healthy.

Location: South facing patio of ground floor apartment. gets a little to much sun in the afternoon.

Problem: Black dust? soot? mold? (I'm not sure) has appeared on the branches. However, I am able to wash this black stuff off with a damp cloth. The bark underneath looks healthy and I have not lost any branching.

Help?
 

0soyoung

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As long as the bark underneath is healthy, it probably isn't anything to worry about. I speculate that it is a sooty mildew. I find it on some camellias, jasmine, and azaleas in my yard during our cool, damp rainy winters here; not every one, just some. The affected plants aren't all in the same location, so it seems to be something about particular varieties. At any rate, I've not had it on any of the 16 different varieties of Japanese maples in my collection; 'viridis' is not one that I have.

You can try a peroxide spray - it is my standard antifungal/antibacterial: 2 tablespoons of 3% hydrogen peroxide (standard grocery/pharmacy stock) in a quart of water. It is very eco-friendly (peroxide breaks down into oxygen and ordinary water). I break out the nuclear options for fungal issues (e.g., benomyl) only as a last resort - I don't think this is necessary/advisable, at this point, for your issue.

On the other hand, if this is a bonsai, you may want to defoliate and spray/paint it with lime sulfur. It too will nix just about any fungus/mold AND your 'veridis' will have that famous white bark we all see in pictures for most of the winter! On a landscape specimen it is a bit too messy and stinky, IMHO.
 

jordystokes

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Thank you for the response!

peroxide spray
I will be trying this out.

nuclear options
Will wait for branch die back before I nuke it.

defoliate and spray/paint it with lime sulfur
will defoliation affect the trees health this late in the fall? And the tree is probably about 3 foot tall 3 foot wide. Not a bonsai yet but I'm developing it to be one.
 

0soyoung

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will defoliation affect the trees health this late in the fall? And the tree is probably about 3 foot tall 3 foot wide. Not a bonsai yet but I'm developing it to be one.
Not particularly.
Deciduous trees harvest the nitrogen compounds in the light harvesting centers before leaf drop (that is why the green chlorophyl color disappears in fall to reveal the caratinoids = orange, xylophyls = yellow, and anthocyanins = red). Growing in your large pot, nitrogen is likely abundantly available, whereas it wouldn't necessarily be in a natural forest setting.
During the growing season, defoliation can be quite taxing on the tree (no leaves = no photosynthesis), so we generally just remove one of each leaf pair and always leave a leafed node when we cut back.

For now I suggest that you enjoy the colors and try the peroxide spray. Since I doubt your tree has anything serious, I suggest you wait until the leaves have dropped to try out lime sulfur. Not to worry if you don't have lime sulfur. It is just an ancient antifungal and just a cute way to paint your deadwood or bark white.
 

Vin

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Not particularly.
Deciduous trees harvest the nitrogen compounds in the light harvesting centers before leaf drop (that is why the green chlorophyl color disappears in fall to reveal the caratinoids = orange, xylophyls = yellow, and anthocyanins = red). Growing in your large pot, nitrogen is likely abundantly available, whereas it wouldn't necessarily be in a natural forest setting.
During the growing season, defoliation can be quite taxing on the tree (no leaves = no photosynthesis), so we generally just remove one of each leaf pair and always leave a leafed node when we cut back.

For now I suggest that you enjoy the colors and try the peroxide spray. Since I doubt your tree has anything serious, I suggest you wait until the leaves have dropped to try out lime sulfur. Not to worry if you don't have lime sulfur. It is just an ancient antifungal and just a cute way to paint your deadwood or bark white.
Holy smoke Batman! That has got to be the best explanation I've ever read about the defoliation phenomenon. We all need to cut and paste this for future reference. Good job! :D
 

0soyoung

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Holy smoke Batman! That has got to be the best explanation I've ever read about the defoliation phenomenon. We all need to cut and paste this for future reference. Good job! :D
Thanks, but I think you exaggerate.
I was just proud of myself for being relatively succinct.

Like to hear about xanthophylls in evergreen conifers? It protects the thylakoids from chemical destruction during the winter.

... just joking ;):D
 

Vin

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Thanks, but I think you exaggerate.
I was just proud of myself for being relatively succinct.

Like to hear about xanthophylls in evergreen conifers? It protects the thylakoids from chemical destruction during the winter.

... just joking ;):D
You lost me at xanthophyllsisisisis. :rolleyes:
 

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