In hot, sunny weather, the bark of fruit trees, especially when they're young, can get sunburned and begin to crack or peel. This allows tree borers and other pests and diseases to enter, which can cause significant damage to the trees. To protect exposed trees, the bark can be painted with white latex paint, mixed 50-50 with water.
If you have a new fruit tree that hasn't been painted, do it now. And consider other fruit tree trunks if they have significant sun exposure.