Estimation of viable propagules of black-foot disease pathogens in grapevine cultivated soils and their relation to production systems and soil properties

[Aims] The study aimed to assess comparatively the accuracy and efficiency of three culture media protocols for estimating black-foot disease pathogens populations in soils and to examine how shifts in the abundance and composition of black-foot pathogens correspond to changes in specific soil properties. [Methods] Firstly, culture media were compared by evaluating the mycelial growth of selected black-foot pathogens and by estimating the population of Dactylonectria torresensis from artificially infested soils. Secondly, the most efficient culture medium was selected for estimating the viable propagules of black-foot disease pathogens in eight naturally infested soils. An analysis of the soil physicochemical properties was conducted. Data were statistically analyzed in order to explore possible relationships between the studied variables. [Results] Glucose-Faba Bean Rose Bengal Agar (GFBRBA) was selected as the most efficient culture medium. All naturally infested soils tested positive for the presence of black-foot pathogens. D. torresensis was the most frequently isolated species, followed by Dactylonectria alcacerensis and Ilyonectria liriodendri. A positive relationship between calcium carbonate and the Colony-Forming Units (CFUs) level of black-foot pathogens in soil was obtained. [Conclusions] In this study, we provide an early, specific, and accurate detection of viable propagules of black-foot pathogens in soil, which is critical to understand the ecology of these fungi and to design effective management strategie