Identification and characterization of Pestalotiopsis spp. causing twig blight disease of bayberry (Myrica rubra Sieb. & Zucc) in China

Bayberry (Myrica rubra) is a fruit tree native to the subtropical regions of China. It produces fruit with a unique taste and pharmacological characteristics, thus making it a widely cultivated tree commercially in many regions of China, including Zhejiang, Fujian, Guizhou, Sichuan and Yunnan Provinces. Recently, a twig blight disease occurred on the fruit tree and caused destructive damage of plantings in the Zhejiang Province. However, the etiology of the disease was unclear. This study was carried out to identify the causal agent(s) of the blight disease on bayberry. Fungal isolates were obtained from blighted twig samples collected from bayberry fields in Xianju, Rui'an, and Huangyan of Zhejiang Province. The majority (87.9 %) of the 257 fungal isolates were identified as Pestalotiopsis spp. based on their conidial morphology. DNA sequences of the internal transcribed spacer (ITS) region of the ribosomal RNA gene and the beta-tubulin gene were obtained from six representative strains (XJ27, XJ42, RA2-1, YS26, YS44 and RA1-2) of the Pestalotiopsis spp. Phylogenetic analysis showed that three of the strains (XJ27, XJ42, and RA2-1) grouped with P. versicolor (Speg.) Steyaert while the other three strains (YS26, YS44 and RA1-2) grouped with P. microspora (Speg.) Batista & Peres. Pathogenicity tests in the greenhouse showed that all these six isolates of Pestalotiopsis spp. caused twig blight disease symptoms on bayberry plants, which were the same as observed in naturally infected plants in the field. Our results clearly indicated that P. versicolor and P. microspora were the major pathogens causing the twig blight disease on bayberry in southern China.