another pic. What could it be?

Look up sun scald in apple trees. That's what it looks like you have there. Also it looks like you have your root stock growing up there, may be a good idea to cut them flush with the surface of your ground. Those new growth coming up out of the ground around your main trunk.

Sunscald is the most likely cause, but there are other ways sections of tissue can die. Fungus decays the dead tissue over summer. A healthy tree walls off the dead tissue, so hopefully the fungus dies out after the dead tissue is consumed. The result is a canker spot like the one i n the picture.

Some people bridge graft over extensive cankers on trunks, but I think that one will be okay as long as it doesn't get more damage on the good side. You might want to checkout the recent post on trunk protection.

Here is a link that might be useful: Trunck Protection

Assuming it is on the west or south side and since it is in Dallas, I too would vote for sunburn. Is that the graft point? Should have been pointed north-east.

Remove suckers. Continue to remove suckers for life.

Remove that nursery stake! I am surprised it has not caused abrasion issues.

Paint exposed trunk white with water based latex paint, half dilute latex paint or protect with a guard. I too think it will be fine as long as there are no other problems. The area looks nice and dry.

Thanks everyone. I had no idea sun scald could be that bad.

Bob