Fruit rots of pomegranate (cv. Wonderful) in Greece

Abstract

Fruit rots are possibly the most important diseases of pomegranates in Greece and worldwide. One of the aims of this study was to identify the pathogens causing pre- and postharvest fruit rots of pomegranate. The results showed that Pilidella granati was isolated from about 60 % of the preharvest rotted fruits without symptoms of cracking. Fungi of the genera Penicillium and Aspergillus niger predominated in rotted fruits with symptoms of cracking. In most of the postharvest rotted fruits, the symptoms developed from the calyx of the fruits. Botrytis cinerea was mainly isolated from these fruits (45 %). P. granati was isolated in 29 % of cases. These pathogens infected all parts of the fruits. Fungi of the genera Penicillium and Phoma sp. were isolated at a low percentage. Two or more of the above pathogens were simultaneously isolated from the same fruit in 15 % of cases. Propagules of the fungi P. granati, Penicillium spp., A. niger, B. cinerea, Alternaria spp., Cladosporium cladosporioides, and Aureobasidium pullulans were detected in the mummified fruit. In the calyx and mouldy stamens, most of the fungal colonies isolated were of the genus Penicillium. A number of colonies of the fungi A. alternata and C. cladosporioides and fewer colonies of the fungi A. niger, A. pullulans, B. cinerea and P. granati were also observed. Finally, the effectiveness of the fungicides tebuconazole, thiophanate methyl, azoxystrobin, cyproconazole and the mix pyrachlostrobin:boscalid to control postharvest fruit rots on pomegranate was investigated. No fungicide was effective in preharvest applications. In prestorage application, the fruits sprayed with tebuconazole or thiophanate methyl showed the least percentage of fruit rots of all treatments. Finally, no fungicide was effective to control fruit rots on pomegranates in poststorage applications.