ABSTRACT
Most of the vegetables are consumed fresh worldwide due to high quality. Vegetables decay is mainly caused by fungal and bacterial plant pathogens resulting considerable postharvest loses. It is well established that these losses are significant (Burchill and Maude, 1986; Pathak, 1997). In underdeveloped and tropical countries these losses have been estimated up to 50 percent (Coursey and Booth, 1972; Jeffries and Jeger, 1990).Vegetables are very susceptible to pathogenic fungi due to have low pH, high moisture content and rich in nutrient composition (Moss, 2002). Out of 100,000 species of fungi, about 10 percent are plant pathogenic and among them about 100 species of fungi are responsible for causing most of the postharvest diseases (Eckert and Ratnayake, 1983). In some tuber crops and brassicas, viral infections present before harvest can sometimes develop more rapidly after harvest. In general, however, viruses are not an important cause of postharvest disease. Postharvest diseases are often classified according to how infection is initiated. The so-called “quiescent” or “latent” infections are those where the pathogen initiates infection of the host at some point in time (usually before harvest), but then enters a period of inactivity or dormancy until the physiological status of the host tissue changes in such a way that infection can proceed. The dramatic physiological changes which occur during fruit ripening or maturity are often the trigger for reactivation of quiescent infections eg. gray mold of carrot caused by Botrytis cinerea (postharvest diseases arising from quiescent infections). The other major group of postharvest diseases are those which arise from infections initiated during and after harvest. Mostly these infections occur through surface wounds created by mechanical or insect injury. The size of the wounds need not be large for infection to take place and in many cases may be microscopic in size. Common postharvest diseases resulting from wound infections include blue and green mold (caused by Penicillium spp.) and transit rot (caused by Rhizopus stolonifer). Bacteria such as Erwinia carotovora (soft rot) are also common wound invader. Many pathogens, such as the banana crown rot fungi, also gain entry through the injury created by severing the crop from the plant.
