My discovery apple tree is about 10 years old and has produced a good crop of apples each year, but it seems to be dying. Two years ago the leaves on one of its branches all withered and died prematurely and the crop of apples on that branch were much smaller in size than those on the rest of the tree. Last year the condition spread to nearby branches and this year it has spread even more affecting nearly half the tree.
I have just cut off the first affected branch to see if anything was wrong inside but the cut end looked OK. The condition only becomes apparent in the summer. The springtime development of the affected branches seems to be normal but during July the leaves wither up and the apples stop swelling and then fall far to early. I live in the Eden Valley of Cumbria and although we were short of rain during July I was able to keep the apple trees well watered and none of our other apple trees are suffering like this.
I am wondering whether to cut off all the affected branches but that leaves the tree very lopsided. Would it stop the rest from dying, though?