Japanese maple help

I live in northern Ca (zone 9 I think) and this year I noticed the bark peeling off the back of my Japanese maple and the wood does not look good underneath. It is only happening on the west facing side of the tree. We didn't have any weather that was out of the norm this past year. The tree has been here since I bought the house 10 years ago so it's between 10 and 17 years old. About 3 years ago I switched to a drip watering in my backyard and put two watering tree stakes on either side of the tree for its new water. Let me know what happened and if it's savable please.

Thank you for your time!!

 

I had a cut leaf that had the same problem. Mine was transplanted about 8 years prior to the problem showing up but 2 years and it was dead so?

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From the photos you posted, it doesn't look like optimal growing conditions for a tree.... if it were a potted plant, which it looks like on a larger scale, I'd say it was root rot and root bound.
What is the raised bed filled with? Is it sitting on top of more concrete pavers, like what is in front of it?

 

The bed is just mounded dirt underneath. The pavers are just to hold up the raised bed.

 

I mean the flat square concrete blocks... do they continue under the dirt the tree is planted in?
I would pull away the dirt around the base of the tree and see what that looks like.

 

Did you raise the bed after the tree was already planted? I don't see a root flare...that could be 1" down or 9" down. Might be part of the problem?

Perhaps some verticillium? Perhaps some sun scald (was the tree recently exposed to more sunlight than it was used to)?