Biological characterization and genetic diversity analysis of two species of Pestalotiopsis causing twig dieback of Myrica rubra

摘要

Chinese bayberry (Myrica rubra Siebold & Zucc) is an evergreen fruit tree with high ecological and economic values in China. In recent years, a new twig dieback disease caused by Pestalotiopsis mangiferae and P. vismiae was observed in major M. rubra-producing areas of Zhejiang and Fujian Provinces, causing serious economic losses. In this study, 16 isolates of P. mangiferae and 27 isolates of P. vismiae were obtained from diseased leaves, roots and branches of M. rubra from different regions. The optimum growth temperature of the two species of Pestalotiopsis was determined to be 20-25 A degrees C, while the optimum temperature for the germination of conidia was 25-35 A degrees C. The two species of Pestalotiopsis showed rich genetic diversity. Inoculating the conidial suspension of one or both of the two species of the Pestalotiopsis on detached leaves or branches of M. rubra could cause lesions surrounding the inoculation sites with the frequency of 100 %. Moreover, necrotic lesions could be observed on inoculated potted plants with the frequencies of 33.3 % for P. mangiferae, 25 % for P. vismiae and 50 % for a mixed inoculum.