I've lost a major branch originating from the base of my Japanese Maple over the last few weeks (all leaves turned brown). The rest of the tree looks fine. I was looking at the dying branch and noticed what appeared to be fine sawdust at the base and possibly some very small holes in that same area (occurs just on dying branch). The bark on this branch is loose at the base. See attachment. Any thoughts on whether this apparent infestation caused the branch to die or if this is more of a secondary issue? The tree was probably under-watered during this timeframe. I'm trying to decide how to treat the rest of the tree and maybe several others I have in the yard depending on the root cause.