This is a Shohin Japanese Maple I’ve been working on for a few years. It has a few major pruning wounds were the height of the tree was reduced. These wounds are healing well but every year I help it heal a little faster. I open the wound around the edge and re-seal it. This forces the tree to produce more callous that it normally would in the year. I have carried out this technique for years on Maples and other deciduous trees with great success.
This is the same tree back in October.
The wounds in question
This is the wound after the edge has been opened. You can do this with a sharp blade or as I do for speed, a dremel. Care needs to be taken to just open it and no more. No point removing a years worth of callous with a dremel!
I then seal the wound again with cut paste.
To finish off a add a thin layer of PVA glue over the paste. This makes a better seal and helps deter the slugs. I know a few people who add slug pellets into the paste to stop them eating it.
If you keep an eye on the paste it’s easy to tell when new callous is growing underneath. You’ll see a crack appearing around the edge like in this photo below taken from a different maple.