I have a crab-apple tree for a few years that was fine, as much as I can tell, however this year it didn't grow leaves. This is south Canada zone and all trees around are green for many weeks now. There was a few days of frost a month back, other plants seems to have handled it well. Also, on the bark there has been that looks like mold for a few years now, it didn't change much.
Basically my question is - does it mean the tree is dead? If not, how can I save it?
For reference, I took these today: