Black-foot disease is one of the main fungal trunk diseases affecting planting material and young vines worldwide. Recently, several fungal trunk pathogens have been isolated from asymptomatic mature vines. Therefore, the objectives of this study were to (i) conduct extensive surveys in grapevine nurseries and identify the fungal species associated with black-foot disease from asymptomatic endorhizosphere tissues of externally asymptomatic plants based on morphological and molecular methods, and (ii) determine the pathogenicity of these fungal endophytic species on grapevine. A total of 3,426 grafted grapevines ready to be planted from 15 grapevine nursery fields in Northern Spain were inspected from 2016 to 2018 for black-foot causing pathogens. In all, 1,427 isolates of black-foot pathogens were collected from the asymptomatic inner tissues of surface sterilized secondary roots and characterized based on morphological features and DNA sequence data. Eleven species belonging to the genera Dactylonectria, Ilyonectria, Neonectria, and Thelonectria were identified. In addition, two species are newly described, namely D. riojana and I. vivaria. Twenty-four isolates representing 13 black-foot species were inoculated onto grapevine seedlings cultivar ‘Tempranillo’. The pathogenicity tests detected diversity in virulence among fungal species and between isolates within each species. The most virulent species was D. novozelandica, followed by D. alcacerensis and I. vivaria sp. nov. This study improves our knowledge on the etiology and virulence of black-foot disease pathogens, and opens up new perspectives in the study of the endophytic phase of these pathogens in grapevines.
This study has been carried out by the BIOVITIS gorup at the ICVV in collaboration with the ‘Estación de Enología y Viticultura de Galicia’ (AGACAL-EVEGA).
This study has been recently published in Plant Disease journal. More information: