From what I have noticed since taking those photos on subsequent tree finds, it always seems that they pick a tree that has had some sort of trauma. The mountain ash pictured, it had been shot with a rifle by one of my nephews and we had it staked and tied to try and save it as the trunk had such a hole and crack in it. The last few trees I found up to the cabin looked like they had big freeze cracks in them where the trunk was split open. Maybe take a look at your apple tree and see if you see any prior issues. It would be interesting to note.