After tree stress, if older citrus fruit are on the tree their rinds commonly split at the bottom of the fruit.

Disorder Development

Tree stress can cause split fruit. Common causes of stress include high temperatures, hot winds, too much or too little soil moisture such as from inappropriate irrigation, and potassium deficiency. Some citrus varieties may be more likely to split than are others.

 

Decay fungi commonly colonize injured fruit resulting in secondary diseases, such as Alternaria rot (Alternaria citri) and blue and green molds (Penicillium species) that cause clear rot. Even when only a few fruit are affected on the tree, pathogen spores developing in split fruit can disperse and heavily contaminate the surface of healthy fruit. After harvest, this pathogen contamination can cause fruit rot during storage.

Damage

Split fruit fail to properly mature. The exposed, internal tissue commonly develops pathogen decay that makes the fruit inedible and results in inoculum that can infect and decay other fruit.

Solutions

Provide trees a good growing environment and proper cultural care to keep them healthy and reduce plant stress. Provide proper nutrition, including adequate potassium. Appropriate irrigation is especially important. The amount of water applied and how frequently must be adjusted according to the weather and trees' changing need for moisture. For example, when hot and windy weather is expected, trees will need more water.

References

Adapted from Citrus, California Master Gardener Handbook Second Edition and Integrated Pest Management for Citrus, University of California Statewide Integrated Pest Management Program (UC IPM).