I am going to go with maple or sweetgum...it would have helped if you got a closeup of the leaves.

Hmm, weird, I tried to post a follow-up with a picture of the leaves but I don't see it now. Let me try again ...

yeah that's some type of Japanese maple....not sure about the fungus

When you get sporocarps popping out all over like that the wood underneath has been infested and attacked for some time.

Outlook not too good.

Problem appears to be 'cottony maple scale'. A few minutes searching should help with positive identification and treatment.

well.. 2 independent ID's ...

if its scale.. its treatable.. but i have never seen such on mature bark ...

if its mushrooms.. as bboy suggests.. i think.. lol ... they are living on the rotting wood under the bark ... time is limited ...

that is a very bad prior pruning.. i am wondering what the prior owner did to the rest of the tree ...

two more pix .. as good a closeup as you can get... and a pic of the whole ...

may as well tell us where you are also ....

ken

ps: why am i wondering if this tree was topped.. or telephone poled ... or any significant construction in the root zone... or all three????

Looks like scale insects! The white patches are the residue left on the bark after a dead scale insect falls off. The brown bits are scale (dead or alive) that are still on the tree.

Thanks for all the messages. I did a bit more reading up on some of your suggestions, and it looks like you're right - scale insects it is.

Seems like I'm too late to deal with them this year - they're in season right now. But I've found some useful info for sorting it next year.

I'm very pleased - I was worried it would be a nasty, well-entrenched fungus. Thanks for the help. Great forum!