Fungal pathogens associated with branch and trunk cankers of nut crops in Iran

Abstract

Branch and trunk canker diseases have become prevalent on nut crops in Iran. During 2015 to 2018, extensive field surveys were conducted on 58 almond, 43 pistachio and 80 walnut orchards in Iran to study fungal pathogens associated with symptomatic trees. One hundred and fifty-six representative fungal isolates were selected and identified based on morphological characteristics and by phylogenetic comparison of DNA sequence data. Fungal species found were Collophorina hispanica, Pleurostoma richardsiae, nine species of Phaeoacremonium (namely P. angustius, P. cinereum, P. italicum, P. fraxinopennsylvanicum, P. minimum, P. parasiticum, P. scolyti, P. tuscanum and P. viticola), 11 species of Botryosphaeriaceae (namely Botryosphaeria dothidea, Diplodia gallae, D. mutila, D. seriata, Dothiorella plurivora, Do. sarmentorum, Do. viticola, Lasiodiplodia citricola, L. mahajangana, L. theobromae and Neofusicoccum parvum), four species of Diatrypaceae (namely Cryptosphaeria pullmanensis, Diatrype whitmanensis, Eutypella citricola and E. vitis) and two non-identified Eutypella spp. (Eutypella sp. 1 and Eutypella sp. 2). Some of these species represent new reports in Iran and/or are reported for the first time in their respective hosts. Pathogenicity tests demonstrated that most of these fungi were pathogenic to inoculated almond, pistachio and walnut shoots. Therefore, more importance should be given to fungal trunk pathogens in Iran, and specific management strategies should be included within the nut crops IPM management programs, with the aim of improving their sustainability.