Morphology and three-locus phylogeny revealed Botryosphaeria dothidea causing leaf spot disease of Populus deltoides in India

Populus deltoides is an important agroforestry tree species in India. Foliar fungal pathogens pose a serious threat to P. deltoides in nurseries and plantations, causing losses to farmers. It is therefore necessary to detect and accurately identify them at an early stage for timely disease prevention and control. In September 2021, leaf spots were observed in P. deltoides plantations in northern India. Fungal isolates representing a Botryosphaeria species were repeatedly isolated from the diseased leaves. Morphological characteristics coupled with phylogenetic analyses of combined internal transcribed spacer, partial translation elongation factor-1α and partial β-tubulin regions confirmed the species identity to be Botryosphaeria dothidea. The pathogenic nature of B. dothidea was confirmed on detached and intact leaves of P. deltoides. Koch's postulates were established by re-isolating the pathogen from the inoculated leaves. This study is the first report of pathogenic B. dothidea causing foliar disease symptoms on P. deltoides in India. [Display omitted] •This study is the first to report Botryosphaeria dothidea causing leaf spots on P. deltoides in India.•Identification was made employing microscopic morphology combined with three-locus phylogenetic analysis.•The fulfillment of Koch's postulates confirms B. dothidea as a foliar pathogen of P. deltoides.•This study highlights the need for comprehensive and accurate identification of poplar pathogens to develop disease preventive and control measures in India.