apple

Hello All, Any information or help with this would be appreciated. My apple tree has been sick for quite some time. Not many apples are grown to full size, many don't fall...and rot on the branch. As well the tree has lots of moss around it. Take a look at the photo below to see what the inside...

We have found an old home site with a 2 acre or so orchard . It is down to about 10-15 trees and the forest has choked off most of it. There are deer,bear,and elk that feed from them so majority of fruit is pretty high. I am looking for advice on how to bring them back to health. The house that...