pm:

Probably bacterial canker. But that's just a semi educated guess. Not much you can do about what you showed.

All that peeling bark means the wood underneath is dead. Don't know what caused it to die.

Any chance of an overall image so we can see the distribution?

Here is full image. Last year my new guava tree started drying out from top branches and then trunk and died later. When I took the dead trunk out, found few worms (borer?) inside. May be my peach tree is having the same problem? I am worried about those holes. I am not seeing any other damage anywhere else yet and enjoying the sweet fruits. Don't want to loose this 5 year old tree. How to fix this?

{{gwi:92361}}

It looks like southwest injury otherwise the tree looks healthy. Perhaps after those lower limbs were pruned. This tree would regrow bark faster with a lighter fruit load. A dilute white latex paint on the trunk prevents future injury.

I agree with Ace, it looks like too much hot SoCal sun on that trunk.

Scott