Fruit splitting is most common on thin-peeled fruit such as Navel oranges.
It generally occurs following stresses such as extreme hot weather combined with high winds or drought stress followed by heavy irrigation.
In both cases, the tree becomes drought stressed and begins to withdraw water from the fruit. When the tree is irrigated the dehydrated fruit swell causing them to split.
The best remedy is to irrigate evenly. When severe winds or high temperatures are anticipated, irrigate before the weather change occurs.
Following the hot winds irrigate lightly for a few days and then resume a normal irrigation schedule.