Several things could causing your cherry tree’s leaves to yellow and fall: The weather has been so unusual this spring and summer with so much rain, that your tree may have gotten too much water.  Cherries like a good soak once every one to two weeks, and anything more could cause your problem.

There are several other possible causes shown on this page from the Michigan State University Extension Service. 

http://msue.anr.msu.edu/news/yellowing_leaves_and_leaf_loss_reported_in_tart_cherries  

Michigan is an important cherry-producing area, so the issues on this page would apply to commercial growers as well as some home gardeners. A viral disease called cherry yellows is a possibility. Another cause could be bacterial canker. 

There are a number of other possible causes, as well, so further research is necessary to determine your problem.  We suggest you call agent Jerry at the Westchester lab of the Cornell Extension Service.  That location has in the past, hosted regular walk-in days where gardeners could bring in samples for diagnosis.  Jerry’s phone number is (914) 285-4620.

Thanks for contacting us, and good luck with your tree!