Leaves of apple tree are going black and dry. Why?
Leaves of Apple Tree Are Going Black and Dry
Certified GKH Gardening Expert
It sounds like a fungus, possibly sooty mold. A general fungicide should help, but if it does have a sooty appearance, it means that you also have a pest problem like aphids. You will also need to treat the tree with a pesticide as well if this is the case.