FACTORS AFFECTING DISEASE DEVELOPMENT

This chapter reviews preharvest factors that affect disease development, along with harvesting, and handling. The first preharvest factor which may affect postharvest quality is the cultivar, since different cultivars may vary greatly in their susceptibility to diseases. In fact, one of the aims of plant breeding and genetic engineering is to incorporate resistance genes in new varieties of crop plants. Differences in cultivar characteristics can markedly affect the keeping quality of the fresh produce. Another preharvest factor is the health of the planting material. Various pathogens may contaminate the planting material and cause disease in the field or in storage. Many pathogens persist in the soil or survive on plant debris in the field, from which winds and rain may be directly responsible for their dispersal to potential hosts. Other pathogens, such as Phytophthora spp., which infect potato tubers or citrus fruits, are actually dependent on rainwater for germination of their spores and initiation of infection.