Hello!

I’m sorry to see your Japanese maple is having a problem.  Thank you for bringing your question to Ask Extension. It may be that your tree problem is caused by verticillium wilt. https://www.canr.msu.edu/resources/verticillium_wilt

The MSU lab can test for this. I would recommend reaching out to them by email first with your question, pictures and tree history - referencing this Ask Extension question #0198762. The address to request a diagnosis is: <personal data hidden>

The lab will let you know if they need any other information or branch samples. There may be a fee involved, but the lab will inform you ahead of time if this is the case.

Another option is to hire a certified arborist to come on site to give you a complete diagnosis and care plan. Here is a link to help you find a local certified arborist: https://www.treesaregood.org

One additional note: This tree was planted too deeply. This tends to shorten the life of a tree. One of the most helpful resources for a homeowner’s with trees: Tree Owner’s Manual

Wishing the very best!