Fungal diversity associated with grapevine trunk diseases in Northern Italy and development of a qPCR for the detection of Botryosphaeriaceae

countries, causing severe economic losses. The colonization of woody tissues by those pathogens can occur at the nursery, where plant material collected from mother plants may already be contaminated. Despite significant knowledge about GTDs etiology and epidemiology, no curative methods are yet available, and prevention remain the most effective strategy. Due to limited information on GTD related pathogens in Northern Italy, a survey was conducted during 2021-2022 to investigate fungal species diversity and distribution associated with symptomatic plants. Four species associated with Botryosphaeria dieback, including Botryosphaeria dothidea, Diplodia mutila, Diplodia seriata and Neofusicoccum parvum, were recovered at high frequency. Additionnal pathogens were also isolated, including Eutypa lata, Fomitiporia mediterranea, Phaeomoniella chlamydospora, Paraconiothyrium brasiliense, Seimatosporium vitis-viniferae and Truncatella angustata. The high frequency of Botryosphaeriaceae isolated from diseased grapevines suggests these pathogens are rising in Italy, as observed in other Mediterranean countries in recent years. A reliable diagnostic tool targeting Botryosphaeriaceae could be used to test propagation material, such as canes from mother vines, at the nursery, and to facilitate the production of healthy cuttings, thus limiting the spread of contaminated plant material. This tool could also be used to facilitate early diagnosis in the field and to help grape farmers to promptly adopt best management strategies. For these reasons, we developed a quantitative method for assessment and quantification of N. parvum and B. dothidea. A qPCR assay with SYBR Green method was developed to detect and quantify the infection levels of both pathogens directly from grapevine wood.