Cytospora canker, a grapevine trunk disease (GTD) caused by various species of the genus Cytospora, has been extensively studied in the US but remains underexplored in Europe, and its incidence and associated species are not truly known. This study aimed to investigate the potential of Cytospora spp. to penetrate grapevine plants through pruning wounds and to molecularly characterize a diverse collection of isolates from this genus. The assay was carried out at a commercial vineyard located in Samaniego, Álava region (Northern Spain). The vineyard in Samaniego was planted in 2001 (19-yearsold) with ‘Tempranillo’ cultivar grafted onto 110 Richter rootstock. On February 2020, 1-year-old canes of 30 vines were spur-pruned to three buds using secateurs, coinciding with the common pruning time in this region. The experiment was repeated the following seasons (2021–22 and 2022- 23), with pruning on the same date. Canes were harvested from vines above the second bud (about 10 cm long pieces) approximately 12 months after pruning and brought to laboratory for GTD pathogens assessment by plating wood fragments onto culture media. Colonies resembling Cytospora spp. were transferred to PDA plates for their identification based on DNA sequence data of ITS region and tef gene. Preliminary analysis identified a total of 347 isolates, representing 8 different Cytospora species. Isolates belonged to C. viticola (n=311), C. cotini (n=25), C. ceratosperma (n=2), C. hippophaicola (n=2), C. salicacearum (n=2), C. salicina (n=1). Notably, we observed four isolates potentially representing two novel Cytospora species, highlighting the richness of fungal diversity responsible for this GTD. This study contributes to the understanding of Cytospora canker incidence and diversity. The identification of multiple Cytospora species, including potential novel taxa, highlights the need for continued research to effectively manage this fungal disease and ensure grapevine health and productivity. Ongoing efforts involve further species identification and phylogenetic analyses using additional genomic markers to enhance phylogenetic accuracy.

Resumen del trabajo presentado en el XX International Plant Protection Congress, celebrado en Atenas (Grecia), del 1 al 5 de julio de 2024