Fomitiporia punicata and Phaeoacremonium minimum associated with Esca complex of grapevine in China

The Esca disease complex includes some of the most important trunk diseases of grapevines (Vitis spp.) and causes serious yield losses in grape production worldwide. However, there has been no detailed study on its presence and associated pathogens in China. During 2017-2019, a preliminary field survey was conducted in eight vineyards in Hebei and Ningxia provinces, China when unusual foliar symptoms were observed. Symptoms were distinct tiger striped leaves, which are typical of grapevine leaf stripe disease (GLSD), one of the most common diseases in the Esca complex. Tiger-stripe leaf symptoms were found in four vineyards, and incidence was cultivar dependent varying with vineyard and year. A total of 266 fungal isolates were obtained from wood tissues of grapevines with typical foliar symptoms of GLSD. Based on morphological characters and multigene-combined phylogenetic analyses, the Ascomycete Phaeoacremonium minimum, one of the pathogens associated with Esca complex was identified. The basidiomycete Fomitiporia punicata, which has never been reported infecting grapevine, was also identified and found to be associated with wood rot in grapevine. The remaining isolates included some known wood pathogens, such as Neofusicoccum species and Diaporthe species. Koch's postulates were performed in the greenhouse, confirming that both F. punicata and P. minimum caused leaf interveinal chlorosis and necrosis that resembled the GLSD symptoms of the Esca complex observed in the field. The present study provides the first detailed report of the Esca complex in China. In addition, this is the first record of F. punicata associated with Esca complex of grapevine worldwide. The results of this study provide new insights into the knowledge of the Esca complex.