First Report of Black Spot Disease Caused by Alternaria alternata in Persimmon Fruits in Turkey

Abstract

In recent years, postharvest rot symptoms have been observed in persimmon fruit (Diospyros kaki L.) during long storage in Hatay Province, one of the main production areas of Turkey. Infection appeared to begin through small cracks around and beneath the calyx. Symptoms developed as small, slightly depressed, dark brown spots. Slices of infected peel were surface sterilized in 1% sodium hypochlorite for 2 min, plated on potato dextrose agar (PDA), and then incubated at 24°C in darkness for 7 days. Hyphal tips from the margin of each developing colony were subcultured on PDA. Fungal colonies were initially white, becoming olivaceous, and turning brown with age. Conidiophores were brown, short, simple, or sometimes branched. Conidia were obclavate, obpyriform or ellipsoidal with a short conical beak, and 18 to 32 μm long and 5 to 14 μm wide at the broadest point. The pathogen was identified as Alternaria alternata (Fr.:Fr.) Keissler based on morphological characteristics (2). Pathogenicity tests were conducted on previously wounded persimmon fruit (cv. Fuyu) by spraying 12 fruits with a conidial suspension (106 conidia per ml). Six control fruits were treated with sterilized water only. All fruit were kept in a moist chamber (100% relative humidity) at 25°C for 3 days, and then moved to a growth chamber at 26°C with a 16-h photoperiod. Many, small, and black sporulating spots were observed on inoculated fruit 5 days after treatment. After 21 days, these spots developed into lesions similar to those produced on naturally infected fruit. No lesions developed on the control fruit. A. alternata was reisolated from inoculated fruit. The disease was previously reported in Israel (1). To our knowledge, this is the first report of A. alternata infecting persimmons in Turkey. References: (1) D. Prusky et al. Phytopathology 71:1124, 1981. (2) E. G. Simmons. Alternaria: An Identification Manual. The American Phytopathological Society, St. Paul, MN, 2007.