I have an old Japanese Maple whose branches are dying out. I discovered a...
I have an old Japanese Maple whose branches are dying out. I discovered a bark issue I cannot diagnose. It is about 30 years old and was purchased as a bare root. It has always been in a good spot, decent sun/shade balance and protected from wind. Included are pictures. The leaves appear fine and there is new growth.
Hennepin County Minnesota japanese maples
I suspect that what you're seeing on the bark are cankers. Damage to the bark allows fungi to enter the tree between the bark and the wood and thus killing the bark. This spot then leaves your tree susceptible to other diseases. If what you're seeing is cankers, it's essential to remove the infected wood before it can spread to the rest of the tree. Removal should happen during dry weather and with sterilized tools.
I would strongly recommend having a tree care specialist out to look at it though, I can only diagnose so much from a photo and a tree care professional will be able to more accurately diagnose the issue and give you advice on how to treat the problem. Often tree care companies will give you a free consultation visit.