CALYX AND STEM MOLD, AFFECTING PEAR FRUIT COSMETIC QUALITY: DIAGNOSTIC, ETIOLOGY AND MANAGEMENT STRATEGIES

SOSA, M.C.; LUTZ, M.C.; CONDOPLO, N.; VERA, L.; FAGOTTI, P.

Bari

Simposio; III International Symposium on Postharvest Pathology: Using Science to Increase Food Availability; 2015

Argentina is the largest producer and exporter in the Southern Hemisphere of short, medium and long shelf life pears. During 2014?s storage and retail, European markets claimed the presence of a white-grayish mold in calyx and stem affecting fruit?s cosmetic quality. In "Packham`s Triumph" and "Beurre d´Anjou" fruits, observation by light microscopy was performed, typical structures of Alternaria spp. and Cladosporium sp. were identified. Koch´s postulates were carried out. Fruits, with mold, which were incubated in moist chamber (22°C-7days) did not developed decay; however, in pathogenicity tests in pear fruits all isolates of Alternaria sp. were pathogenic. The infection by Alternaria sp. and Cladosporium sp. could be originated in the orchard from spores that infect, and remain dormant until the tissues become senescent during storage. Hence, monitoring of the fungal microflora of stem, sepals and fruit bottom (calyx) was performed. Both pathogens grew from setting fruit, with prevalence in sepals of Cladosporium sp. (20%) at 15 days after full bloom (DAFB) and Alternaria sp. (76%) at 60 DAFB. In the search for putative management strategies, effectiveness of pyraclostrobin and boscalid fungicide was evaluated. This inhibited the mycelial development of Alternaria sp. (98%), and of Cladosporium sp. (100%). In 2013-2014 the effectiveness of the fungicide in controlling mold of pear fruit, was evaluated in the orchard. A single application 7 days before harvest diminished the incidence of stem mold. Furthermore, the effect of disinfectants over cross contamination in tank immersion (line of packing) was evaluated. Peracetic acid was the best disinfectant since reduced the incidence of mold in about 33%, even after storage to 30ds at -1/0°C plus 7ds at 22°C. The calyx and stem mold of pear fruit by Alternaria sp. and Cladosporium sp. can be controlled using combined strategies pre and post-harvest improving the cosmetic quality of the fruit.