Turkey ranks the fourth in pistachio production in the world with 78, 000 tonnes produced annually (Tuik, 2017). The production areas of pistachio (Pistacia vera L. ) are predominantly in the Southeastern Anatolia region, where accounts for 97% of the total pistachio production in Turkey (Tuik, 2017). During the 2017 and 2018 years, a severe foliar blight, decline and dieback of pistachio trees were observed in the region, in 15-year-old commercial pistachio orchards established in Birecik county of Ş anlı urfa province. Incidence of disease ranged from 16 to 64%. The observed symptoms included shoot blight with scorching of leaves, branch wilt, decline, trunk canker and death of trees (Fig. 1a). The twigs of infected pistachio trees showed necrosis and internal vascular discoloration (Fig. 1b). Gummy exudation was frequently associated with the affected tissues. In this study, we identified and characterized this fungal pathogen, based on its morphology, molecular characteristics, and pathogenicity...