Postharvest disease survey on pomegranate fruit in South Africa

Pomegranate (Punica granatum) is mainly produced as a fresh commodity in South Africa, destined for export to northern hemisphere markets from February to July. Postharvest rot causes economic losses to producers and a disease survey was done on fruit to determine the scope of fungal pathogens involved in postharvest decay of pomegranate fruit in South Africa. The survey was further refined by evaluating the effect of the current standard industry postharvest treatment protocol of a chlorine (100-150 mg L^‑1) and fludioxonil (230 g L^‑1 active at 250 mL 100 L^‑1 water) drench on the amount and type of pathogens isolated. Fludioxonil is presently the only post harvest chemical registered for pomegranates in South Africa. A significantly lower amount of fruit with decay symptoms was observed after fruit was treated with chlorine and fludioxonil and stored for 12-14 weeks at 7°C. A quantitative evaluation indicated a reduction of up to 100% in some production units of postharvest rot symptoms in treated fruit. The survey indicated the presence of a variety of fungi including the genera Alternaria, Botrytis, Botryosphaeria, Cytospora, Penicillium and Pilidiella. A comparison was made between isolates found on treated and non-treated fruit to determine the need for alternative or additional postharvest treatments for isolates currently not efficiently controlled by the present standard protocol applied by South African pomegranate pack houses.