Pathogen Identification and Resistance Screening of Fusarium Basal Rot in Taşköprü Garlic in Türkiye

Fusarium basal rot (FBR), caused by Fusarium spp., is a significant threat to garlic production globally, including in Türkiye, where the unique Taşköprü garlic is highly valued. This study investigated the diversity and aggressiveness of 77 Fusarium isolates obtained from disease surveys of FBR in Taşköprü garlic and evaluated the yield and resistance of 20 garlic accessions, including 18 local landraces, the locally developed ‘Taşköprü 56’, and the commercial Chinese variety ‘ASCG’. Molecular identification using translation elongation factor 1-α (TEF1) and second largest RNA polymerase II B-subunit (RPB2) genes revealed F. oxysporum (67.5%) as the dominant species, followed by F. proliferatum (15.6%), F. solani (9.1%), F. redolens (5.2%) and F. clavum (2.6%), respectively. All isolates were pathogenic, but aggressiveness varied, with F. solani being the most aggressive, followed by F. redolens and F. oxysporum. While ‘ASCG’ exhibited the highest yield (3.15 ton/ha), it was highly susceptible to FBR (DSI = 97.50%). Conversely, the landrace ASTK2 displayed the highest resistance (DSI = 53.13%), but lower yield. Promisingly, several Taşköprü landraces, such as ASTK6 and ASTK13, demonstrated both moderate resistance and promising yield potential. Surprisingly, ‘Taşköprü 56’, despite being a locally developed variety, exhibited high susceptibility to FBR (DSI = 93.75%) and did not outperform many landraces in terms of yield. This study provides the first reports of F. redolens and F. clavum infecting garlic in Türkiye, and the first molecular characterisation of F. solani as a garlic pathogen in the country, highlighting the potential of local landraces for breeding FBR-resistant, high-yielding cultivars.