Decay of citrus fruit is most often caused by fungal pathogens that grow and develop in the hot and wet conditions typical of the Florida climate. Losses from these diseases can be reduced by the practices discussed in this 6-page revised fact sheet written by Mark A. Ritenour, Jiuxu Zhang, and Megan Dewdney, and published by the UF Department of Horticultural Sciences, February 2011.
http://edis.ifas.ufl.edu/ch081