Mutsu apple with bark removed with pocket knife

Sorry you don't have an answer yet. it's not fire blight, but I don't know what it is. There are some really experienced guys here that will hopefully show up soon.

I've never seen canker that looks like that, and I look at an awful lot of apple bark over the coarse of every year. You may need to contact your local county extension and have a Davis pathologist scope it.

I'm assuming there was no evidence of any tunneling under the wounds.

I am wondering if it is damage from sunburn. It looks similar to sunburn I have had on the trunks of younger trees.

Looking at it closer I think something ate the cambium layer. What do I need to do to protect the tree?

You need to find the cause before you do anything to it.