Journal of Plant Pathology Archive

Abstract:

Pomegranate (Punica granatum L.) is an important crop in Greece. In spring 2011, plants of cv. Wonderful with symptoms of apoplexy were observed in Vrodou Katerinis, (northern Greece) which, at close examination revealed the presence of collar rot. Isolations from the lower margins of necrotic areaa in acidified PDA (2.5 ml 85% lactic acid per litre of medium to obtain a pH of 3.5 after autoclaving) yielded colonies with a white mycelium that turned green to dark brown and produced dark coloured pycnidia 300 to 500 μm in diameter after 15 days. Hyphae were septate, conidia were hyaline, allantoid to ellipsoid (average 4-6 x 4.5-5.5 μm). The pathogen was identified as Cytospora punicae Sacc. based on morphometric traits and MEGABLAST comparison of the 600 bp long sequence amplified with ITS4/5 primer pair with those from database (GenBank accession No. KJ621688). Pathogenicity tests consisted in carving with a cork borer a 6 mm hole in 1-year-old shoots of pomegranate cv Wonderful, in which an agar plug excised from a 15-day-old culture of C. punicae was inserted. Inoculated shoots were incubated at 25°C for 15 days, after which 32 to 41 mm necrotic spots developed. Controls inoculated with sterile agar plugs remained healthy. Re- isolation from diseased shoots of the same fungus used for inoculation fulfilled Koch’s postulates. Control shoots inoculated with sterile agar plugs showed no symptoms. C. punicae has recently been reported to cause wood canker and branch dieback of pomegranate in California (Peduto Hand et al., 2014), but, to our knowledge, this is the first report of C. punicae infections in pomegranate plants in Greece.