Parasporendocladia bactrospora associated with canker and dieback of walnut trees (Juglans regia L.) in Iran

The walnut (Juglans regia L.) tree is considered one of the most important fruit trees in Iran. Decline disease of walnut trees is one of the significant problems that have been noticed in different regions of Kerman province (South-eastern Iran) during the last ten years. Therefore, a study was conducted to identify the fungal species associated with walnut trees showing trunk diseases between May 2015 and September 2016. Collected symptomatic wood samples were cut and surface disinfested with NaClO (Sodium hypochlorite) and then plated onto potato dextrose agar (PDA) plates. In this study, 21 isolates of a fungus were isolated from trees showing canker and dieback, and internal wood necrosis in the Bidkhun region of Kerman province. The obtained fungal isolates were first identified and grouped based on the most important morphological characteristics. Total genomic DNA was extracted and identification of the isolates was confirmed by sequence analysis of ITS (the internal transcribed spacer) using the primers ITS1 and ITS4. Based on the most important morphological characteristics and molecular data, these isolates were identified as Parasporendocladia bactrospora. This study is the first report of this species associated with canker and dieback symptoms on walnut trees worldwide and also the first report of this fungus for the funga of Iran.