The white that you are seeing there is a type wood decay fungus. The branch union has included bark and the fungus suggests that there is rotting wood in those areas.  Upon closer look, the fungal growth appears to extend into the main trunk. 

This is of concern as the tree is weakened an will die but it likely won't be for a while- perhaps even years. We don't think there is anything you can do, but enjoy it while it lasts. (Unless of course it's dropping of limbs would threaten people or property.)

The wet wood at the base and the lack of widening/flare before it goes into the ground suggests that the tree was planted or mulched too deeply, which can add to decline and eventual  death for a tree. 

Christine