Pathogen-dependent susceptibility of fig cultivars to four Nectria canker pathogens

Abstract Background : Fig Nectria canker, caused by various members of the Nectriaceae family, has recently emerged as one of the most destructive trunk diseases threatening fig production in Iran, the world’s fifth-largest fig producer. Methods : This study presents a comprehensive evaluation of cultivar-specific susceptibility to four emerging Nectria canker pathogens: Neocosmospora caricae , N. metavorans , Fusarium annulatum , and F. decemcellulare . Result : Aggressiveness assessment of the species isolates revealed significant intraspecific variation across the isolates. Principal component analysis (PCA) classified isolates into three distinct aggressiveness groups: high, moderate, and less aggressive, enabling representative selection for cultivar screening. Eight fig genotypes, strategically chosen to represent commercial, wild, and stress-tolerant genotypes, were inoculated with the most aggressive isolates. Two-way ANOVA showed that pathogen species strongly influenced external lesion progression and incubation period, while cultivar identity shaped both external and internal lesion traits. Significant pathogen species and cultivar interactions confirmed that susceptibility is pathogen-dependent rather than intrinsic. Multivariate clustering and radar chart visualization revealed that no cultivar was uniformly susceptible or tolerant: ‘Sabz’ and ‘Atashi’ were consistently highly susceptible, whereas ‘Brown Turkey’, ‘Gilasi’, and ‘Matti’ displayed relative resilience. Temporal progression assays highlighted distinct infection signatures : N. caricae and N. metavorans sustained rapid lesion expansion; F. annulatum exhibited delayed onset with mid-course acceleration; and F. decemcellulare remained weak, plateauing early. Standardization of pathogenicity traits further reinforced these species-specific profiles, providing a transferable framework for quantifying aggressiveness. Conclusions : This study demonstrates that fig cultivar susceptibility to Nectria canker pathogens is inherently pathogen-dependent and trait-specific. By integrating controlled inoculation assays with advanced statistical approaches, we establish a methodological model for precision evaluation of fig genotypes for breeding and sustainable disease management.