Qualitative and quantitative molecular analysis indicate the presence of Phaeomoniella chlamydospora in vineyard soils

During the past two decades, esca disease has emerged as one of the most important diseases of grapevines. Esca is caused by complex of fungal pathogens, one of the main being Phaeomoniella chlamydospora (Pch). Since propagation material is considered one of the main infection sources of this fungus, most studies on Pch detection have focused on plant tissues and nursery soils. Conversely, due to methodological limitations encountered in retrieving this slow‐growing fungus, little is known about its true occurrence in vineyard soils. This study presents the adaptation of a molecular‐based methodology for the detection and quantification of Pch in soil samples. For this purpose, soil from the root‐explored area of esca‐foliar symptomatic and asymptomatic plants was sampled in 17 adult vineyards in two different climatic regions. Qualitative and quantitative nested PCR assays indicated the presence of Pch DNA in soil, differentiating between vineyards and regions, regardless of esca symptoms. The number of positive samples (32%) detected in the vineyards indicates that Pch can be recovered in natural soils, thus opening perspectives for the use of molecular tools in the study of the ecology and epidemiology of this fungus in soil.