That is probably Apple Scab. It has been wide spread this year.  It is not fatal.  Sanitation is important.  Clean up and dispose of all leaves as they fall. Next spring you will have to spray at 'green tip' (when the leaves are just barely starting to come out) with a fungicide meant for the fungus.  As far as production, apple trees mostly produce on an every other year basis.  As the trees get older and larger, there are some apples every year but every other year will produce a larger crop.  I do have some concern though about the trunk protection I see in the photo.  Those plastic sleeves are wonderful for protecting from rabbits but should be removed around April 1st and put back on around October 1st.  They do not breathe and I have seen trunks rot from the build up heat and moisture.  https://extension.umn.edu/plant-diseases/apple-scab