After lots of blossom, the leaves at the tips of each branch curl up and the blossoms go dark brown and wither up with the immature fruit falling off!!
Has the tree grown successful crops in the past?
Cherry Run Off can help every few years; the tree produces more fruit that it can support, so it drops the fruit.
This can occur when temperatures are low and days are cloudy.
There can also be environmental factors, herbicide drifts, improper nutrition, or irregular irrigation.
You can have a soil test done to determine if you need to make adjustments to fertilizers or amend soil.