Can you please check the photo and let me know what is causing the tree branches joint to dry.
Toronto Master Gardeners receive many queries about Japanese Maples.
Your concern with one specific area is a little different. Notice that the branch joint is almost flat and exposed. There appears to be a slender whitish growth emerging in the centre. And there are multiple branches coming out from the larger joint. Keeping the area clear of potential clogged debris, pruning severely, and ensuring that soil improvement and adequate watering occurs regularly will improve the overall health of the tree. I recommend consulting a professional arborist.
Here is a link to our Toronto Master Gardeners Guide Growing Japanese Maples, which provides lots of information on how to care for these trees and what can afflict them.
Also see Japanese maple .
SF Gate’s Verticillium wilt on Japanese maple provides additional information.
I suggest that you contact an arborist for a final diagnosis. If you don’t know of one, check out Landscape Ontario for a list of arborists in your area.
Another one of our archived posts titled Damaged Trunk on a Japanese Maple gives information on the proper cultural practices to help your tree.
December 5, 2020