Improved evaluation of foliar anthracnose resistance in strawberry for a sustainable management of Colletotrichum gloeosporioides

BACKGROUND: Anthracnose, caused by Colletotrichum gloeosporioides sensu lato (Cg), severely impacts strawberry and other crops, primarily infecting foliage via rain or overhead irrigation. Previous reports on strawberry foliar resistance to Cg are partially controversial because of methodological variations and rapid pathogen evolution in agroecosystems. Recent phylogeny analysis using next-generation sequencing enabled re-identification of strawberry pathogenic Cg strains from Eastern China (2007-2023), providing a basis for renewed investigation into host-pathogen interactions. RESULTS: Site-specific inoculation of eight re-identified Cg strains on detached leaves revealed partial strain-host specificity. Analysis of variance differentiated strains in terms of pathogenicity (lesion counts) and virulence (lesion diameter). Nonparametric correlation and linear regression modeling indicated that the inoculation method exerted the strongest influence on disease severity, followed by fungal ecotype and host genotype. Disease severity in a whole-plant assay did not correlate well with that in a detached-leaf assay, but the severity in leaf blade and petiole was closely linked. Screening 32 Fragaria genotypes via whole-plant spray-inoculation with C. fructicola (CGMCC3.17371) identified 'ShenYi' and 'MiaoXiang7#' as resistant as Fragaria vesca 'Hawaii4', which was consistent with field observations. CONCLUSION: Detached-leaf inoculation is suitable for assessing Cg pathogenicity and virulence. Whole-plant spray-inoculation integrated with an in vitro leaf assay is recommended for host resistance evaluation. This study establishes a foundation for deploying genetic resistance in strawberry breeding programs, and enabling sustainable anthracnose management through targeted cultivar development and screening protocols. © 2025 Society of Chemical Industry.