FIRST REPORT OF Pilidiella granati ON POMEGRANATE WITH SYMPTOMS OF CROWN ROT IN FARS PROVINCE

In summer 2014, plants of pomegranate (Punica granatum L.) with crown rot symptoms was observed in the Firozabad and Siakh-Darengon area in Fars Province. The symptoms were very similar to Phytophthora crown rot. Surface-disinfested tissues from the lower margins of the necrotic area were plated on acidified potato dextrose agar (PDA) and Phytophthora selective antibiotic medium (CMA-PARP). To insure the presence or absence of Phytophthora, the soil around the crown of pomegranates was also baited with citrus leaf discs for 48h at room temperature and plated on CMA-PARP. Plates were incubated at 25ºC for 5-7 days, and consistent colonies with white or yellowish cream-colored mycelia and abundant black, globose pycnidia were observed on PDA and no fungi were recovered on CMA-PARP. Conidia were hyaline, one-celled, ellipsoid to elongate, 9.9 to 16.7×2.03 to 4.2 µm (average 13.8×3.05 µm). On the basis of morphology, the causal organism was identified as Pilidiella granati Saccardo (Synonym Coniella granati (Saccardo) Petrak and Sydow). Pathogenicity tests were conducted using detached twigs of pomegranate. 7-mm plugs bearing mycelia from the edge of 10-day-old colonies on PDA were placed under the bark of twig. Noncolonized PDA plugs were used as controls. The wound was covered with parafilm and all inoculated twigs were incubated at 25ºC for 10 days, at which time necrosis was observed. No lesions were observed on the controls. Reisolation of the fungus from the inoculated twigs was attempted to satisfy Koch's postulates. This pathogen has been previously reported as a cause of post harvest decay, fruit rot and dieback of pomegranate in the world and Iran. It has been recently reported to be associated with crown rot in Greece and Turkey, as well as in Iran (Lorestan Province without any pathogenicity test). This is the first report of P. granati from pomegranate plants with symptoms of crown rots in Fars Province. Factors involved for predisposing pomegranate to the fungus need further studies for disease management.