It's Apple scab.
What you should do no is rake all the leaves that fall and burn or compost them after adding lime. You may want to fertilize with urea and zinc to encourage leaf drop: the spores overwinter on the leaves, alive or dead, so they must be disposed of.
The spores are dispersed by wind and fungal growth is encouraged by high moisture: for next year plan to protect the tree from overhead irrigation if you have any.
Since you now know Apple scab is in your area, next year as soon as the leaft tips emerge spray the tree with a copper based fungicide. If the season is wet you may consider using a captan or tebuconazole fungicide to protect the tree, but remember fungicides must be applied at the onset of wet weather and are preventive, not curative.
