What kind of fruit?

usually failure to form fruit is due to failure for the flowers to be pollinated when the tree was in flower. failure could be lack odf suitable pollinators, frost, lack of water and no other compatible tree of the same type nearby.

but as Owd asks which fruit tree are you talking about.

In a young tree most of the young crop is often dropped around midsummer - the tree knows how much fruit it can support! Known as the June drop.