Answer: It doesn't sound good for your Japanese maple! You didn't say how old the tree is, how long it has been planted in its current spot and whether or not you fertilized or used chemicals near the tree. If the leaves all dropped and you're seeing black streaks on the branches and trunk, it could indicate a disease. I can't diagnose it without seeing it so you may want to cut off an affected branch and take it to your local Cooperative Extension or Master Gardener clinic for further inspection. Helpful folks there will take your trees' history and diagnose the problem. Best wishes with your landscape!
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