I have several cherry trees, the cherries are dropping while still green and they have brown spots on them. I have them sprayed by Rasmussen spray service 4 times a year.
Marion County Oregon cherry trees
These symptoms could be caused by a disease such as Coryneum blight or Pseudomonas. Finally, it could be that they are dropping due to incomplete fertilization. A certain percentage of cherry fruit on trees will fall naturally in what is known as June drop. Some years it is worse than others. Here is more information about these two diseases.
http://pnwhandbooks.org/plantdisease/cherry-prunus-spp-bacterial-canker (see the spots on the fruit in the picture.)
http://extension.usu.edu/files/publications/factsheet/coryneum-blight08.pdf (see the spots on the apricots in the picture.