Postharvest stem-end browning (SEB) disease in ripe mango ( Mangifera indica L.) cultivar TomEJC

Browning of the fruit peel around the stem-end region of ripe mangoes, cultivar TomEJC, was observed in a commercial mango plantation in Dambulla, Sri Lanka (Central Province) in 2016. The condition was recognized as a fungal disease, new to mango and named stem-end browning (SEB). The disease commenced as a diffused, yellowish-brown ring around the pedicel and expanded with ripening, covering the upper one-third of ripe fruit. The lenticels within the affected area darkened. A 2–3 cm diameter peel, immediately surrounding the pedicel and the pulp underneath, turned necrotic. The disease did not lead to any softening of the fruit tissues. Ten fungi, isolated from the peel of symptomatic or health fruit, were identified by multi-gene phylogenetic analysis as nine species, Curvularia dactyloctenicola, Diaporthe endophytica, D. eugeniae, D. pseudophoenicicola, Fusarium mangiferae, Neocosmospora sp., Neofusicoccum brasiliense, Neopestalotiopsis rhizophorae and Pestalotiopsis adusta. Most of these fungi could also be isolated from the pedicel or the peel of younger, developing fruits, 2, 4, 6, 8, 10 or 12 weeks after anthesis. Pathogenicity of isolates was tested and confirmed. All nine species produced lesions, slightly variable in size, shape or colour from each other, 8–10 days after inoculation. Different colour forms of the SEB were observed in certain fruit harvesting seasons, probably depending on differences in pathogen combination and dominance. SEB substantially reduced fruit quality, incurring 12–27% postharvest fruit losses. The study describes symptomatology, inoculum source, mode of fruit infection, the identity, phylogeny and pathogenicity of fungi isolated.