The info you got before is correct an old now healed wound probably from the winter or the freeze or the move.....keep an eye on it if black areas appear in spring it may be Pseudonomous and should be treated with fungicide... it comes out in cool damp weather and as the summer progresses often just sort of disappears and the wound heals ...then in the sping it starts again.Its mostly on the root stock which is good so if it is more than just winter damage you should try to KEEP it there !!! and not let it spread up the tree. In addition as long as it stays on one side the tree will live if it encircles it it's toast above that point...but as i said that is a worst case scenareo of disease and you should know next spring for sure ...as far as I'm concerned for now do nothing and wait... if you want to loosly put a plastic tree guard around it i guess that wouldn't hurt but that would be it for now..David

It was said:
"keep an eye on it if black areas appear in spring it may be Pseudonomous and should be treated with fungicide"

Let's assume that's an oops. Pseudomonas is a bacterium rather than a fungus.

Further, I would skip any plastic wrap. The tree has already dealt with the crack by covering it. Plastic wrap can cause problems because it holds moisture against the bark.

OOPPS hard springy plastic tree guard are not plastic wrap ...they are completly covered with ventilation holes and can bee put on loosely or tight. Whether they are necessary is debatable ( except for critters) ...and are usually taken off in spring ...They are NOT [plastic wrap or any solid wrap which is never recommended IMHO.I doubt this problem was caused by anything other than the winter freeze to heat and back again as we had throughout this past winter in this zone and for many of us in the fall as well when the sap was running ( NOT the wrap!!!) I have seen it on many maples ...but the spring will tell...but I think that is likely the culprit...Of course any wound can be a either caused by disease/ fungus or can be a harbour for such thus the wait and see suggestion ..David

Thank you all for your responses. I went out and took some better pictures today. It looks like the bark is peeling away in more places than the big one I noticed. I've never seen it do this before.

The first picture is of the whole tree from the front. The last picture is from May of 2006 before I lost a lot of the right side of the tree to the freeze of April 2007.

Your help is much appreciated as I really really want to save my tree. If you have any suggestions on where I could find a pro to look at it, please let me know.