evergreen oak

Anyone have any thoughts on what might be happening here? Noticed the bark splitting over the last couple months, seems to be more growth popping up low by the splits. This lower trunk used to be bare. Today I came out and saw this white, powdery growth at the base. We had a very hot summer...

Curious if anyone has used these for bonsai subject or had any luck with them. I have one in my yard thinking of maybe getting some cuttings of or doing a possible air layer as I don't have any oaks and thought might be fun to play around with. Couldn't find much online about them as bonsai.