Apples on the lotty

I planted a few fruit trees a couple of years ago and they seemed to be doing well without actually producing any fruit. However, the leaves on the apple tree have recently turned brown, curled inwards and died! I sprayed the two adjoining trees, a pear and plum, with an anti fungus treatment but it appears that the disease has also spread to them. The difference is that the leaves have gone black rather than brown and don't seem to be curling up yet.
Any ideas/advice on what's going on? I've cut the apple tree back as hard as I dare and burned the diseased branches and leaves.

How do you know it's a disease causing the problem?

If you get a strong cold wind at the wrong time of year it can cause the same effect. I usually get a few burned leaves on young trees every year, especially on the pear which seems particularly sensitive.

Yes I had the same with my hazel hedge wind burn