Investigations of the pre-harvest fruit rot pathogens in the Adana - Mersin pomegranate groves and inoculation methods performed at different periods on disease incidence

Pre-harvest fruit rot is an important fungal problem and causes serious losses in pomegranate orchards. The aims of the study were; to determine pre-harvest fruit rot in pomegranate orchards in Adana and Mersin provinces, to detect fungal pathogens associated with fruit rot and to reveal the effect of inoculations performed at different times on disease prevalence. Totally 39 orchards were surveyed in 2018 and symptomatic fruits were sampled. Fungal pathogens were isolated with standard mycological isolation procedures and identified with classical and molecular methods. Pathogens were inoculated at two different periods (flowering-fruit set and fruit growth stages) in field conditions, fruit drop and calyx rot incidence were calculated respectively. According to results, the prevalence of fruit rot in Adana and Mersin were found to be 70.6% and 22.7% respectively. The average disease incidence in these provinces was calculated as 5.0% and 1.1% in the same order. Alternaria sp, Aspergillus niger, Aureobasidium pullulans, Botrytis cinerea, Colletotrichum sp., Diaporthe ambigua, Nigrospora oryzae, Penicillium and Talaromyces species were isolated from the symptomatic fruits. Some of these fungi caused fruitlet falling 87.5-100% off when inoculated at the fruit set time, however the dropping rates were 60-70% in the control treated with tap water. These results indicated that all inoculated species were pathogenic on flowers and fruitlets and they caused falling off these parts. However, when the fruits reached half size, only Coniella granati and Diaporthe ambigua inoculations caused calyx rot of the fruits, other species could not. Key Words: Pomegranate, pre-harvest, fruit rot, Alternaria, Colletotrichum, Diaporthe ambigua