Thank you for contacting us regarding your apple tree.  The photos you sent are good, but are not quite enough for us to make a diagnosis.  Would it be possible for you to bring in a diseased branch for us to look at?  Are you seeing any black leaves or a white powdery substance on the leaves?  Are there any webs, even tiny ones?  Spraying for apple problems needs to be done very early in the season as a preventative.  What you can do at this point is remove any fallen leaves from under the tree and prune off limbs that are affected.  Be sure to sterilize your pruning shears between each cut with a Clorox and water solution, 9 parts water to 1 part Clorox.  Below are some links relevant to potential problems your tree may have:

http://extension.usu.edu/files/publications/factsheet/apple-pests.pdf 

http://www.ext.colostate.edu/mg/gardennotes/612.html

http://extension.colostate.edu/topic-areas/yard-garden/backyard-orchard-apples-and-pears-2-800/

http://extension.colostate.edu/topic-areas/yard-garden/fire-blight-2-907/

http://extension.colostate.edu/topic-areas/insects/spider-mites-5-507/

We will try to help further if you are able to bring in a sample of the problem.  The master gardening office at Douglas County Fairgrounds is open M-F 9-12:30 and 1:30-4:30.

Douglas County Master Gardeners