Diaporthe neotheicola, a new threat for kiwifruit in Greece

Although kiwifruit is considered as a crop with few phytopathological problems, new diseases have been identified in the last few years. This study is the first report of a shoot blight and canker disease of kiwifruit in Greece caused by the fungus Diaporthe neotheicola. The fungal species was identified based on fungal morphology and the analyses of the nuclear rDNA internal transcribed spacer (ITS), and the translation elongation factor 1-alpha (TEF-1α) gene regions.The pathogen caused distinct cankers on shoots of kiwifruit, while pycnidia were observed on the blighted shoots. The rate of development of D. neotheicola in vitro was reduced as temperatures increased from 25 to 30 °C, decreased from 20 to 10 °C, and was totally inhibited at 35 and 2–4 °C. The rate of conidial germination and the length of germ tube in vitro were reduced as temperatures increased from 25 to 30 °C, decreased from 25 to 10 °C, and was totally inhibited at 35 and 2–4 °C. A preliminary study on the effectiveness of the fungicides thiophanate methyl, carbendazim and tebuconazole against the development and germination of conidia of D. neotheicola and the disease symptoms was conducted. All fungicides were effective against the fungus in vitro. In addition, no canker was observed on artificially inoculated shoots treated with the fungicides. In general, the disease could be a threat for kiwifruit in Greece and its management should be investigated in the field.

► The first report of the Diaporthe neotheicola as a pathogen of kiwifruit in Greece. ► Developing at optimum temperatures increased from 25 to 30 °C. ► The fungicides thiophanate methyl, carbendazim, and tebuconazole were effective.