Susceptiblity of common rootstock and scion varieties of grapevines to Botryosphaerianceae species

This study investigated the susceptibility of the most common rootstock and scion varieties used in New Zealand grapevine nurseries and vineyards to Botryosphaeriaceae species. A total of six rootstocks and six scion varieties were inoculated with mycelium of three isolates each of the most common Botryosphaeriaceae species (Neofusicoccum luteum, N. parvum and N. australe) recovered from New Zealand grapevine nurseries. Overall results showed that all isolates produced necrotic lesions on all varieties but susceptibility varied significantly (P < 0.001) with 5C and SO4 being the most susceptible of the rootstock varieties, and Merlot and Pinot noir being the most susceptible of the scions. Pathogenicity also varied significantly (P < 0.001) between species with N. parvum being the most virulent among three species tested. This study has further shown that different isolates of the three species have different levels of virulence providing evidence that these pathogens are genetically diverse. These results have significant implications for the New Zealand grapevine industry as the use of resistant varieties is not a possible option at present since none of the common varieties are resistant to these pathogens.