Your lovely citrus trees have gone from blossom, to green fruit, to nearly done when - oh, no! - a significant number of fruits crack and split open just before they are ripe enough to eat.
It is frustrating to the home gardener to have put so much effort into caring for fruit trees only to lose most or all of a crop, but this particular problem is preventable.
Citrus fruit split is not caused by pests or disease. Instead, it is believed to be a watering issue that commonly occurs from September through November. The exact cause is still not yet understood, but botanists believe that citrus splitting is related to extreme fluctuations of humidity, soil moisture, temperature, and fertilizer levels. Fruit split can also occur in tomatoes and pomegranates.
When a citrus tree becomes drought-stressed, it will pull moisture from its own fruit and the leaves will appear cupped. If the tree is then heavily irrigated in an attempt to “make up” for the water that wasn’t provided earlier, the fruits then swell so fast that the skins crack. These cracks normally begin at the navel, or stylar, end, where the rind is weakest. Navel oranges are the most likely to develop citrus fruit split.
Rather than compounding the problem of insufficient water during hot, windy weather, water the tree lightly for a few days, slowly building up to normal moisture levels. The same is true for fertilizer. If your citrus trees are experiencing drought, rather than feeding large amounts in April, June, and August, you may want to feed lighter amounts during the growing season, February through May.
While split oranges are technically edible, most of them are not ripe enough to taste very good. Since these fruits are susceptible to diseases, such as Alternaria rot, as well as fungal and bacterial diseases, insects. and other pests, it is a good idea to discard these fruit or put them in the bottom of your compost pile.
I hope this information inspires you to grow more of your own food. You can ask your garden questions on my Home page.