Unveiling Diversity and Cultivar Susceptibility of Botryosphaeriaceae Species Causing Grapevine Decline in Serbia

Grapevine trunk diseases (GTDs) are a major global threat to viticulture, yet data on their etiology and epidemiology remain scarce in Serbia and southeast Europe. This study provides the first comprehensive analysis of Botryosphaeriaceae species associated with GTDs in Serbia, combining morphological characterization, temperature-growth assays, multilocus phylogenetic analyses (internal transcribed spacer, beta-tubulin, and translation elongation factor-1α), and pathogenicity testing. A total of 46 isolates were collected and identified as Botryosphaeria dothidea, Diplodia seriata, and Neofusicoccum parvum, confirming their role as the primary causal agents of grapevine decline in the region. Significant species × temperature interactions were detected, with optima at 20 to 30°C for B. dothidea and D. seriata and 25 to 30°C for N. parvum. Phylogenetic analyses revealed low multilocus sequence variation across global grapevine B. dothidea isolates, suggesting limited diversification, while N. parvum and D. seriata showed greater phylogenetic structuring. The detection of shared multilocus genotypes across grapevine and other woody hosts highlights the potential for cross-host pathogen movement in mixed-crop landscapes. Pathogenicity assays revealed significant species × cultivar interactions, indicating differential host responses depending on the pathogen-genotype combination. Larger lesions were recorded on 'Merlot', 'Chardonnay', and 'Pinot Gris' cultivars, while 'Drenak' and 'Moldova' were less susceptible. D. seriata and B. dothidea caused the largest lesions. These findings provide a critical base for regional grapevine Botryosphaeria dieback surveillance and emphasize the need for coordinated biosecurity, breeding, and management strategies to decrease disease risks at both local and global levels.