Bleeding canker on Japanese Maple

[stefandidonato]

Hello all,

First time post, excited to join the community! Still learning the ropes on how the forum works.

I have a Japanese Maple that I dug out of my backyard around 5 years ago. It was heavily stunted and had a lot of deadwood (... I know not typical for a Japanese Maple) but I was just starting the hobby and needed trees to practice with! It has since become sentimental as I have moved out of the house I was in.

It has recently developed a bleeding (bacterial?) wound where I assume something has gotten in through the deadwood above.

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It seems to be doing okay in terms of health, foliage is still green - a little crispy after the hot dry summer we've had but generally fine - and I have moved it into a protected spot that gets morning sun but no rain to keep the trunk from getting wet. I have applied some Mancozeb and Lime Sulphur but not sure if effective.

Any advice on what treatment I should follow? I have done some googling and it hasn't inspired a lot of confidence in me (they basically say to cut off infected branches and to pray to any and all gods if is on the trunk).

Thanks in advance! Happy to provide more photos if that would help.

Stefan

[stefandidonato]

I'm not sure if the photo uploaded properly so this is my second attempt!

20250222_093849~2.jpg

Any advice is appreciated! Thanks!

Stefan

[shibui]

Welcome, Stefan.
All good on the second try with the photo.
I can't help with a definitive diagnosis.
Deadwood in itself is not a problem for most trees. I have a number of maples with various deadwood features but no ongoing problems.
Japanese maples are affected by a number of diseases. Some that cause gradual dieback similar to what you are seeing but I have not heard of a cure so if this one doesn't survive don't be too disappointed.
I'm guessing the infection is probably confined to the living parts of the tree - bark, cambium or sapwood immediately below the cambium. Infections do not seem to affect or travel through the inner wood which is essentially dead wood. This means it might be possible to excise an infection from the trunk without resorting to chopping the whole tree.
There's a couple of things you could try:
1. Systemic fungicide in case the problem is fungal infection.
2. Excise around the infected area to remove infection then treat with something like lime sulphur which not only preserves dead wood but also kills almost all infections - insect, fungal and bacterial(?)

Good luck with the tree

[stefandidonato]

Thank you for your prompt reply Neil!

I have a feeling that the maple had this infection lurking inside long before I removed it from my yard (hence the reason it had all the deadwood already).

I had used Mancozeb as a soil drench but it isn't systemic. I'll look into finding a systemic option.

I also used a diluted lime sulphur on the trouble areas but it looks like my best chance is to remove the bark and apply the sulphur to the deadwood underneath. Time to practice my shari skills I guess!

Thanks for the luck! I'll take all I can get!

Stefan

[shibui]

I have a feeling that the maple had this infection lurking inside long before I removed it from my yard (hence the reason it had all the deadwood already).

My thoughts too. I've seen other garden JM that slowly deteriorate with similar symptoms so it is not uncommon. At least you've had some experience maintaining and pruning while it has been in the pot.

I also used a diluted lime sulphur on the trouble areas but it looks like my best chance is to remove the bark and apply the sulphur to the deadwood underneath. Time to practice my shari skills I guess!

My guess is that you'll need to get the treatment, in this case lime sulphur, right to the infection. That's why I recommend removing the bark. You should be able to see when you get to the edges of the affected area when the inner bark and/or wood underneath change colour. I would go a bit past the affected area into healthy looking wood in case the infection has moved into surrounding tissue.
Use lime sulphur at 50/50 with water to paint onto the bare wood.

I would also clean and sanitise all tools you use on this tree in case the problem can be transmitted to other trees from residue on tools. My suggestion would be to clean tools well with soap and water then dip all surfaces in metho or other alcohol.

[stefandidonato]

Here's a photo of the maple with the infected bark removed. I have used lime sulphur on the bare wood and keeping it out of the rain (not that we have had much in SE suburbs of Melbourne).

Wish me luck!

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[TimS]

Good luck, honestly come spring/ summer (late October for us melbournians) i'd be looking at doing an air layer here at the red line and casting off the lower section to avoid future issues with rot/ pests etc.

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[stefandidonato]

Hi Tim,

I think you may be onto something. I have been hoping to keep the trunk since I designed and 3D printed a custom treehouse for it. But for the sake of the saving the tree, it may be best to air layer the top - that way I can keep the tree on my bench and not in the green waste!

Thanks!

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[TimS]

The treehouse is super cool!

Now i feel bad for saying you should air layer it haha, Keep the trunk just be vigilant for rot and using a wood hardener (I think Earl's is the go-to brand for bonsai people) as maples do rot quite quickly will slow that down dramatically. And yes lime sulphur is a good idea too

Also look out for borer insects too (little piles of wood frass and poop appearing on the soil surface will let you know they're there.

[stefandidonato]

I still think it is a good idea.

I'll see how it goes come spring flush and see how comfortable I am to keep the trunk. I had to remove a larger portion of the bark than I had anticipated. Thanks for the tips if I do keep it!

There will be more trees and more treehouses in the future!

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