Now that it's getting colder, mice will look for anything they can eat, including tree roots and bark. I lost a 20 year old grape vine a few years ago when they ate all the roots off just at the soil level during a prolonged cold snap. Killed the grape vine just as if I had taken an axe to shear it off at its trunk base.

Originated at the Morden Research Station, Agriculture Canada, by C. R. Ure for the Prairie Fruit Breeding Cooperative, selected as P. A. 13 by the University of Alberta, Edmonton, tested as PF51, and introduced for commerce by the Beaverlodge Research Station in 1990. The tree is moderately vigorous, rounded, and has a strong framework It is hardy to zone 2b but is moderately resistant to fire blight and susceptible to cankers. The fruit is medium large, 6-7cm (2.5-3") in diameter, round to oblong with a shallow stem cavity and shallow basin. It matures in early to mid September. The skin is moderately thick, light green base, streaked and washed with several shades of red with lighter lenticels. The flesh is greenish white, very crisp, aromatic and with a pleasant nutty flavour. It is very good to excellent for fresh eating, good for cooking and juicing, and stores for 14 weeks but looses its flavour towards the end. Note: The cultivars >Norda= and >Norkent= which are presently on the market, are nearly if not completely identical. It is unlikely that two crosses so diverse could be so similar in all aspects. The mix up may go back to the original material sent for testing. Do not pick early . The fruit must mature fully to develop full flavour. Norkent

Steal, I won't pile on to the derision towards this invasive plant. Oops....I guess I just did. In any case, I tend to agree that mechanical injury was a likely cause of this canker or canker-like lesion. The truth is in the pudding, that being in this case whether or not the tree is able to form woundwood/callus tissue to close off the wound from the outside. Too early to tell. If it should happen that the wound does not close, then you've got some infectious agent or other happening there, and these are typically next to impossible to treat. But for now, no special requirements beyond the usual-keep the tree watered if drought should strike. Not much beyond that, and even that only in extraordinarily dry circumstances.

I think it has come to the end of its viable life. It is not in good health and I'd suspect you are only looking at further decline. The white growths on the bark appear to be the early signs of bracket fungus, which is an indicator of heartwood rot. The peeling sheets of bark support that. I'd also agree the surrounding concrete is not helping and may very well be accelerating the process. A shame, as Gravenstein is one of the world's tastiest apples! Certainly is my favorite :-)