Diagnostic survey on the occurrence of pineapple fruitlet core rot and relationship with phenolic compounds in Réunion Island

Fruitlet core rot (FCR) is a postharvest disease which develops once the pineapple fruit reaches maturity. In the tropical island of Réunion, it mainly occurs during the winter season. The two fungi responsible Talaromyces stollii and Fusarium ananatum cause black spot in the flesh of the fruit. These internal damages make the FCR difficult to diagnose for the producers and consumers. To get a better idea of the extent of the disease, we conducted a survey of agricultural practices over 27 plots distributed throughout the island. In total 540 pineapples were sampled to determine the occurrence of the disease. During the winter season, almost all pineapples had the FCR symptoms. In order to assess the variability of fruit susceptibility to FCR, 80 pineapple fruits were inoculated with a solution of F. ananatum spores (10³ sp. mL^‑1). Free and bound phenolic acids were monitored in the healthy and infected fruits. High level of phenolic compounds in healthy fruits provides resistance to FCR. All the infected fruitlets react to the fungal infection with a high accumulation in free and bound phenolic compounds. The links between certain mechanisms of resistance and cultural conditions are discussed. The problem of the fruitlet core rot is certainly underestimated in view of its strong presence.