From the picture, it appears that the problem may be cherry leaf scorch or leaf spot. Cherry leaf scorch and leaf spot are diseases of Prunus spp. caused by the pathogenic fungi Apiognomonia erythrostoma and Blumeriella jaapi. The leaves either shrivel, turn brown and remain hanging on the tree overwinter in the case of leaf scorch, or become yellowed, mottled and drop prematurely in the case of leaf spot.

Leaf scorch:

• Leaves become blotchy and brown in summer, then completely brown and shrivelled
• Hard spots may develop in fruit
• Affected shoots are not shed, but remain hanging on the tree during the winter

Leaf spot:

• Leaves develop purple spots, sometimes small holes ('shotholes'), or bright orange colouration and drop prematurely
• Alternatively, leaves develop a blotchy, yellow appearance and drop prematurely
• Under wet conditions, flecks of white fungus may be seen on the underside of affected leaves

For leaf spot, collection and destruction of fallen leaves will reduce the amount of fungus available for infection the following year. Removal of shrivelled leaves affected by leaf scorch would have the same effect, but is not usually feasible. No chemical controls are specifically available for these diseases, but applications of copper fungicides to control bacterial canker may give some incidental control.