One of my Japanese maples in training has been suffering recently. It’s a Sango Kaku, famous for their normally pink bark and bright green leaves. Any ideas?
Discoloration of bark – beginning of dieback?
Note the withering of leaves and unusual colour of sections of trunk.
Extreme windburn?
I wonder if it’s a combination of things? It’s been in semi shade and well watered all year but never really took off in spring. Not much extension growth despite fertiliser being used and in the past couple of weeks the foliage has withered – I also noticed a white discoloration similar to mildew??? I’m familiar with mildew on my oaks and field maples but never my Japanese maples. I’ve sprayed it anyway and put the tree in the ground to help it recover. Fingers crossed.
Scratch Bonsai 
A wet Summer has helped fungal attacks, drying winds in between and Autumn is coming early, I’d strip the dead leaves and start afresh next year. A wee spray with fungicide or a winter wash might help too Ben.
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Good advice cheers Ian. Strange how every species can be affected differently. I have field maples which normally are blighted with mildew but have been fine this year but I suppose they have been in full sun all year and this maple has been in semi shade. Must be the siting of individual plants is a bigger factor than I thought.
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I agree with bonsai eejit. Weather: I’ve got a few maples standing next each other and enjoying morning sun. The heat waves of this summer and hot wind have burnt the leaves of red-leafed (atropurpureum, dissectum) varieties, but the green ones (sango-kaku, deshojo, arakawa) are OK. Fungal disease is possible as well. If you apply fungicide I think it’ll be fine next spring again and you might not lose either single branch. This seems to be not life-threatening but good to notice.
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Thanks PG. It’ll get some preventative treatment and hopefully it’ll take off again next year.
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I’m sorry to see your tree suffering so and loosing leaves… but I am also interested in your photos because my A. Peaches and Cream has also lost most of its leaves. Very sad . Mine has buds and I think the hot, dry weather is to blame . Will new leaves open this late in the season ?
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Very unlikely unless it stays quite mild and you’re feeding with high nitrogen content. As Eejit mentions above, best to strip dead growth and take precautions over winter to encourage healthy growth next year. Its a real shame maples can suffer so much like this, they are treasures of the garden, bonsai or not.
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Thank you for the information. This is my first attempt to grow a potted Acer. It is a seedling, not a pruned Bonsai, and about 18″ tall. I have been stripping the leaves as they die. I believe mine may have been attacked by a larvae of some sort in addition to the weather. We have another 6-8 weeks, at least, before a frost. Would it be better to leave it in the pot, or plant it in the ground this fall? How do potted Maples respond to freezing temps in their pots? Thank you for your advice- I’m a total newbie here 😉
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Hi WG,
Any plant in a pot that has been suffering will probably recover better in the ground, even more so with shrubs like acers that can suffer badly in frost conditions. I would plant it in the ground. The response of potted maples to freezing conditions can depend on a lot of factors including soil composition, if the plant is root bound, amount of rainfall prior to frost and I think it may be prudent to slip yours out of the pot and into the ground soil which will insulate against frost better than a pot.
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Thank you very much for this. I will follow your advice will all of my potted Acers then- all were seedlings this year and are in relatively small pots. You’ve taught me something, as I just assumed that Acers were hardy and wouldn’t suffer in freezing conditions. Thank you for your advice! Best wishes, WG
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You wouldn’t even have to take them out of the pot – if they are cheap plastic containers you could put them straight in the ground and that way you can lift them easier in the spring without much root damage.
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They are in ceramic pots, both glazed and unglazed. But I could move them into nursery pots for the winter… Thank you for the tip!
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