Identification and pathogenicity of Cytospora isolates associated with canker and dieback disease on pomegranate, in East Azerbaijan and Golestan provinces

 Pomegranate is one of the economically important products in Iran. In order to identify the fungal agents involved in canker and dieback disease on pomegranate trees, during the different seasons of 2017-2018, samples were taken from pomegranate orchards with these disease symptoms in East Azerbaijan and Golestan provinces. Disease symptoms appeared as leaf chlorosis, dieback, leaf drop, particularly in the upper crown, longitudinal cankers on branches and trunk, bark cracking and vascular discoloration wood. Disease incidence was rated about 8 percent. A total number of 178 symptomatic wood samples were collected from pomegranate orchards in two provinces. Ultimately, 171 fungal isolates were recovered from symptomatic tissues. Cytospora punicae was determined as the dominant fungal agent with the isolation frequency of 75 percent, based on combination of morphological characteristics and sequence data of ITS region. Koch’s postulates were fulfilled using the excised shoot method. The results of pathogenicity assay confirmed C. punicae being pathogenic of pomegranate. The results of present study determined C. punicae as the cause of canker and dieback of pomegranate trees in East Azerbaijan and Golestan provinces. With the identification and determination of the cause of this disease, in future it will be possible to adopt proper disease management strategies.