That looks like an old mechanical injury. How long have you had this tree and where are you located (nearest city & state)? Thanks.

Planted it in May 2023. I’m in Ohio (Great Lakes Zone 5b/6a).

check with a local arborist or a university extension group. If this is a fungus you want to make sure it doesn’t spread to other trees or weaken this tree.

I’m actually wondering if this might be a result of sun scold on the trunk or a mechanical injury, as Cecily 7A stated.

I agree with cecily. I doubt it is a disease. Japanese maples have very thin bark and it is easily damaged - mechanical damage, frost/sun scald, critters, etc. The fact that the wood is firm and solid under the lifting bark would also lead away from the notion of a fungal disease.

NK, we were typing at the same time :-))

I’m definitely thinking sun scald now because it’s in the south / south west face of the trunk. The powder I’m seeing might be decay? But under that, the wood is solid. I also noticed some raised wood around the edges which tends to be a sign of the tree healing itself. I was hoping you’d respond, Gardengal. Thanks!

Also, I don’t mind this cosmetically because I do a lot of work with bonsai and I just feel it gives the tree more character. I was mostly concerned about this powdery residue underneath the cracked bark I pulled away.

The brown residue is most likely just the dried remains of dead inner bark tissue or periderm, a thin layer that separates the different types of inner bark tissue from the outer bark.

Whatever the damage is from you could give it a few years to see if it gets better. You can always replace it.

I did find one interesting thing when googling that tree. It appears they are possibly usually grafted onto hardier root stock, maybe to be able to withstand harsher weather or maybe because of easier way to propagate the tree. Maybe the damaged area is in area where the graft is.

https://www.bonsainut.com/threads/coral-bark-maple-sango-kaku-will-mature-bark-color-hide-the-graft.53732/

I had rabbit damage to a ornamental flowering crab and the tree eventually died but sent up shoots. I allowed to grow and I trimmed to have a new tree. It seemed to be much healthier and more robust than the original. But much to my surprise we got crab apples after about 5 years. I kept it and I let neighbors take the crab apples to make apple butter and feed livestock and deer.

Want to give an update to this post… I lost this tree. It did not leaf out this year. I had to dig it out today.

Sorry to hear about your loss.

Thank you for the update.