POTENTIAL USE OF PLANT EXTRACTS TO REDUCE POSTHARVEST FUNGAL ROTS OF FRUITS AND VEGETABLES

摘要

Fresh fruits and vegetables are susceptible to attack by several pathogenic fungi and bacteria after harvest. After being detached from the plant, fruits and vegetables initiate the process of ripening (intake of oxygen, breakdown of carbohydrates, carbon dioxide and water vapor production, and heat output), providing thereby nutrients and water for development of microorganisms and losing the intrinsic resistance that protected the horticultural commodities during their preharvest life (Snowdon, 1991; Eckert, 1991). Many postharvest diseases can be acquired during the growing season, postharvest handling, transport and storage of fruits and vegetables. Most postharvest pathogens are wound parasites that depend mainly on exogenous nutrients for germination and initiation of the pathogenic process. An exception to this infection process is the anthracnose disease (Colletotrichum spp.), well documented in a broad range of commodities such as papaya, tomato, avocado, mango, citrus, and others (Kendrick and Walker, 1947; Alvarez and Nishijima, 1987; Binyamini and Shiffmann-Nadel, 1972; Brown, 1974; Johnson et al., 1993). In general, Colletotrichum attacks during fruit growth but symptoms are observed during ripening and softening after harvest (Coates and Gowanlock, 1994). On the other hand, other microorganisms such as Botrytis cinerea can cause latent and wound infection, depending on the host attacked. Regardless of pre- or postharvest infection, once infection has taken place secondary spread to an adjacent host is initiated, causing nesting of infection. Therefore control of these microorganisms is mostly required during the storage life of agricultural commodities (Mercier, 1997).