Neofusicoccum vaccinii: A Novel Species Causing Stem Blight and Dieback of Blueberries in China.

Abstract

Blueberries (Vaccinium spp.) have been considered to be a superfood because of their health benefits. Stem blight or dieback of blueberry has been frequently observed in commercial plantations, with incidences between 15 and 30% being observed in China. The causal agents of blueberry stem blight and dieback were surveyed at four commercial blueberry plantations in the Shandong, Fujian, Guizhou, and Yunnan Provinces of China during 2017 and 2019. Twenty-eight isolates of Neofusicoccum were obtained from 75 diseased and dead stem samples. Two taxa were identified. Of these, one novel species, Neofusicoccum vaccinii, was identified based on morphological characteristics and DNA sequence analysis of the concatenated internal transcribed spacer, the translation elongation factor-1α gene, and the beta-tubulin gene. Koch's postulates tests indicated that N. vaccinii was pathogenic toward blueberry. N. parvum is the other species isolated in this study. The optimal temperature for mycelial growth was 30°C for both N. vaccinii and N. parvum. N. vaccinii, however, was more virulent than N. parvum in this study at temperatures ranging from 25 to 30°C. Coinoculation of N. vaccinii and N. parvum did not lead to increased disease severity. On the contrary, the aggressiveness of N. vaccinii was suppressed by the presence of N. parvum at 25 to 35°C.