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POSTERS: Postharvest pathology and mycotoxins

Pre-harvest monitoring of postharvest rot pathogens in European pear
Achala Nepal - Southern Oregon Research and Extension Center, Oregon State University. Ann Rasmussen- Oregon State University

Several pathogens are involved in postharvest rot diseases in pears that affect both consumption and marketability of fruits. While some pathogens infect through wounds at harvest, some pathogens establish earlier in the season and remain latent until storage. A study was conducted to understand the seasonal prevalence of these pathogens in two pear orchards in southern Oregon. The samples were collected at pink bud, full bloom, petal fall, fruitlets, and field bins. Four pathogens previously reported as postharvest rot pathogens, Botrytis cinerea, Penicillium expansum, Cladosporium herbarum, and Alternaria alternata were identified. At pink bud stage, all the pathogens were isolated in equal frequencies. At full bloom until fruitlets stage A. alternata was most frequently isolated, followed by B. cinerea and C. herbarum. From the field bin samples, C. herbarum were frequently isolated. Several other fungal species were isolated along with the pathogenic species, the identity of which were established based on sequencing of the ITS and elongation factor 1-alpha genes. They were grouped into thirteen unique species, pathogenicity of which were tested in wound inoculated fruits. Out of thirteen, three new species, Dothiorella iberica, Diaporthe rudis, and Fusarium avenaceum were identified as pathogenic on wound inoculated fruits. The three new pathogenic species were present at full white, full bloom, and petal fall stages. This study suggests the possibility of developing postharvest rot disease management programs earlier in the fruit developmental stages.