Flowering cherries are susceptible to many problems, including cherry virus diseases, canker, twig blight, root rot, brown rot, powdery mildew, bacterial and fungal leaf spots, borers, aphids, tent caterpillar, and scale. Bark is thin and easily damaged by mowers and string trimmers. Reduce chances of disease and insects by keeping trees healthy with irrigation in extended drought and regular fertilizer applications.

There have been multiple reports of flowering cherry trees suffering from a fungal disease commonly known as 'brown rot'. This disease normally attacks fruiting peach trees and sometimes other stone fruit trees, but it has jumped to the ornamentals. It is prompted and exacerbated by the cool, damp spring weather we have experienced recently. So far we have observed that otherwise healthy trees are able to survive the disease and put out new growth later in the season. Since it is weather dependent, another cool, wet spring next year may cause another outbreak. Repeated outbreaks may prompt some homeowners to begin a fungicide spray regimen each year to prevent the disease. It cannot be cured once it appears on the foliage. If the affected limbs die, it would be appropriate to prune them out. In the meantime, we simply have to wait and see how the tree recovers.  

You should also check to see if your roots are girdling around the base of the tree.  This may be the cause of the suckers emerging around the base of the tree.  Unfortunately, there is not much that can be done about girdling because it is the result of improper planting. You should prune the suckers as they appear.  

You should also be on the look-out for tent caterpillars that emerge about this time of year.  They should be removed and burned as soon as they appear to limit damage to the tree. 

I have included a link to a Penn State fact sheet that provided additional information of and treatment options on fruit and ornamental cherry trees.   http://extension.psu.edu/pests/plant-diseases/all-fact-sheets/cherry-diseases