Hello,

I am sorry you had to wait for a response.  I received this question today and made it a priority to answer.

I think your tree may have a fungal disease common to cherry trees called cherry leaf spot.  This is usually much worse when we have a wet spring, but still possible this dry year.  Here is some very good information about what this disease is and how to manage it:

https://extension.umn.edu/plant-diseases/cherry-leaf-spot

When watering the tree, make sure to water at the base, avoiding wetting of the leaves.  In the fall, make sure to clean up and bag all the leaves that have fallen from the tree.  If the condition persists over several years, a fungicide can be used.  The article discusses several choices.  Always follow label directions and consider using the least toxic choice first.  (In this case the copper.) 

I hope this answers your questions.  Thank you for contacting Ask Extension!

Ruth