Thank you for writing.

Without seeing a picture of the disease, I cannot be sure.  It is most likely apple scab.  Here are pictures of the most common diseases.  https://local.extension.umn.edu/sites/local-extension.umn.edu/files/download/Managing%20Apple%20Diseases%20Brochure_1.pdf

As to why your plants did not bloom this year, there are a couple possibilities.  The buds could have frozen in the late frost.  The pollinating tree could be gone. Or the tree could be overfertilized or over pruned. https://extension.psu.edu/home-orchards-why-is-there-no-fruit-on-my-tree

I hope this gives you some clues.  Feel free to write back.



Those apples look like apple maggot.  https://extension.umn.edu/yard-and-garden-insects/apple-maggot  Given that you do not have fruit this year, there is not much to do.  The link I gave you talks about prevention.  I think the best method is to prune duplicate blooms to reduce the number of fruit. Shape the tree to be easy to harvest and then go for a larger yield of larger, fewer fruit.

This is a good discussion of pollination. https://homeguides.sfgate.com/far-apart-should-apple-trees-crosspollinate-47422.html  It requires two trees that can cross pollinate and which bloom at the same time.  They should be 50-75 feet apart.  Pollination is not windborne.  One must have bees. 

The use of pesticides to control things like wasps, japanese beetles, grubs, etc has a huge effect on available pollinators. https://www.mepartnership.org/wp-content/uploads/2015/10/MN-neonics-factsheet-03-24-15-FINAL.pdf

Lawn garden environments that suppress 'weeds' with herbicides make it harder for bees to coexist with apple trees.  For example, dandelions are one of the first feasts for recovering hives in the spring.  Apple trees bloom a bit later. If the bees have starved or gone elsewhere, pollination is diminished.