Impact of preharvest application of biological control agents on postharvest diseases of fresh fruits and vegetables

During the storage of harvested commodities, environmental parameters are quite stable. For this and other reasons, it is generally believed that biological control by means of microbial antagonists may have a greater potential for success when applied postharvest. However, one of the major obstacles to the development of postharvest biocontrol agents is that they are unable to control previously established infections, such as latent and quiescent infections and incipient infections occurring through wounds resulting from harvesting operations. Field application of biocontrol agents may enable early colonisation of fruit surfaces, thus protecting from these infections. Moreover, preharvest applications can be an appropriate strategy for fruits and vegetables subject to damage in postharvest handling. To be successful in preharvest applications, putative biocontrol agents must be able to tolerate low-nutrient availability, UV radiation, high temperature and dry conditions. Some reports of postharvest biological control accomplished by preharvest applications, include apples, avocados, sweet cherries, grapes, and strawberries. This paper provides a brief overview on particular aspects of preharvest application of biocontrol agents to reduce postharvest decay. Research areas relevant for the development of this strategy are also indicated. (C) 2000 Elsevier Science Ltd. All rights reserved.