Pestalotiopsis Species associated with Blueberry Leaf Spots and Stem Cankers in Sichuan Province of China.

Abstract

Blueberry leaf spots and stem cankers caused by Pestalotiopsis spp. has become a serious threat for the production of blueberry in Sichuan Province. To characterize the etiology of the diseases connected with these fungi, samples showing leaf spot and stem canker symptoms were collected from the main twelve blueberry growing areas of Sichuan Province from 2015 to 2020 and used for pathogen isolation. A total of 91 fungal isolates were obtained with preliminary morphological identification and 48 representative strains were selected for further pathogenicity test and molecular identification. Four species including P. clavispora (N. clavispora) (57.14%), P. trachicarpicola (28.57%), P. chamaeropis (13.19%) and P. adusta (1.10%) were identified based on conidial morphology, cultural characteristics, and phylogenetic analysis of internally transcribed spacer region, partial sequence of β-Tubulin gene, and the translation elongation factor 1-α. Pathogenicity tests showed that four species were pathogenic to leaves and stems of blueberry. Among them, P. clavispora (N. clavispora) was the most aggressive as the predominant species to cause both leaf spot and stem canker. P. trachicarpicola and P. chamaeropis were mainly isolated from leaves but also pathogenic to stems. P. adusta was only isolated from stems but also pathogenic to leaves. To the best of our knowledge, this is the first report of P. chamaeropis and P. adusta as pathogens causing leaf spots and stem canker on blueberries. The results provide helpful information in disease diagnosis and management of blueberry.