posted 7 years ago
It looks like a branch was torn off in that spot.
Unlike human skin and flesh, trees cannot re-grow bark over a large wound like that. The tree will try its best to slowly grow around the wound and seal it off, but it cannot heal it (the way your skin grows back and within 5 weeks there is no evidence of a scrape).
So, at best, your tree will be able to compartmentalize that wound.
When trimming branches, it's best to trim them back to the "collar" where the branch begins to flare into the main trunk. Leaving only a circle of inner wood exposed, the collar will hopefully seal that wood off in the next few years. For small branches (small wounds), it's far easier. But for large branches, it opens a pathway for fungal attack on the core of the tree. Eventually, that will be the demise of the tree.
If I were you, I'd try to take that tree back and see if you can get one without such an egregious scar. Even if you've already planted it, pull it out, re-pot it, and see if you can get a better specimen.
"The rule of no realm is mine. But all worthy things that are in peril as the world now stands, these are my care. And for my part, I shall not wholly fail in my task if anything that passes through this night can still grow fairer or bear fruit and flower again in days to come. For I too am a steward. Did you not know?" Gandolf