Citrus is susceptible to a wide variety of postharvest fungal diseases including:  Penicillium decays (Blue mould, Green mould, Whisker mould), Alternaria rot, Anthracnose, Aspergillus rot, Brown rot, Cottony rot, Dothiorella rot, Fusarium rot, Gray mold, Pleospora rot, Sour rot, Stem-end rot, and  Trichoderma rot (Whiteside et al., 1988). Factors such as growing region, production practices, cultivar, rootstock, and postharvest practices influence susceptibility to each of these pathogens (Kader and Rolle, 2004).

Postharvest decay is the most important factor limiting shelf-life of citrus. Natural resistance to disease of fruits generally decline after harvest due to ripening and senescence, leading to decay and physiological impairment with severe economical loss. Sams (1999) discussed the pre-harvest factors that affect the post-harvest life of a fresh produce, which include soil conditions, moisture, temperature, relative humidity, nutrient availability, etc.

Production practices such as fertilization, agrochemical substances, type of irrigation, etc. could greatly affect pathogen population and attacks. Furthermore, handling procedures in the field and during harvest and marketing processes cause various kinds of mechanical injuries (wound, bruising), which are the main sites of entry of pathogens, particularly in environments which are highly contaminated by conidia of Penicillium italicum Wehmer and P. digitatum (Pers.:Fr.) Sacc. (packing lines, storage rooms, means for transportation, etc) (Jeffries and Jeger, 1990). These two pathogens are responsible for severe economic losses worldwide (Eckert and Eaks, 1989).

Losses from postharvest spoilage of fruit and vegetables have been managed primarily by applying fungicides (Holmes and Eckert, 1999). However, the use of chemicals is becoming increasingly restricted because of the development of pathogen resistance and consumer concerns about fungicide residues in the food. These issues have resulted in an intensive search for safer control options that pose minimal risk to human health and to the environment (Wilson et al., 1994).