Botryosphaeriaceae species associated with the die-back and canker of olive trees in Iran

Species of the Botryosphaeriaceae have a worldwide distribution and some species of have been recognized as important pathogens on various trees worldwide. In order to identify the Botryosphaeriaceae species associated with olive trunk diseases, a survey was conducted on trees in Kerman and Mazandaran provinces. In 2016, wood samples were collected from trunk and branches of trees showing dieback and canker symptoms. Fungal isolations were performed from discolored wood tissues on potato dextrose agar (PDA). In this study 56 fungal isolates resembling Botryosphaeriaceae species in colony and culture were obtained from affected trees. All isolates were identified using morphological characteristics and partial sequences of the translation elongation factor 1-α gene (tef-1α) with the primer pairs EF1-728F and EF1-986R. Based on morphological and molecular analysis five species of Botryosphaeriaceae namely, Botryosphaeria dothidea (11 isolates), Diplodia seriata (8 isolates), Dothirella sarmentorum (8 isolates), Lasiodiplodia theobromae (7 isolates) and Neoscytalidium hyalinum (22 isolates) were identified. A pathogenicity trial was performed on detached shoots of olive under greenhouse conditions. Diplodia seriata isolates were the most virulent species based on the length of wood necrosis. This study is the first report of D. seriata and L. theobromae from olive trees in Iran. In addition, this study is the first report of Do. sarmentorum associated with yellowing, canker and dieback symptoms of olive trees.