Harnessing Microbial and Plant Genetic Diversity to Combat Strawberry Anthracnose: Testing A European Collection of Aureobasidium pullulans Strains and Wild Strawberry Genotypes Against Colletotrichum acutatum

Strawberry anthracnose, caused by Colletotrichum acutatum, is a major production obstacle due to its rapid disease development, latent infection cycle, and spread through symptomless plant material. This study investigated a dual biological approach for controlling anthracnose by combining microbial antagonism from Aureobasidium pullulans strains with host resistance in wild Fragaria vesca genotypes. The novelty of this work lies in its simultaneous, large-scale assessment of microbial and plant genetic resources, moving beyond single-factor strategies to integrated, biodiversity-based disease management. A total of 183 A. pullulans strains, collected from diverse European habitats, were screened in dual culture assays against C. acutatum. Inhibition of radial growth (PIDG) ranged from 0 to 35%, with the highest suppression from a strain from the United Kingdom (35%), and several others maintaining inhibition above 25%. Volatile-mediated inhibition assays, conducted on 18 selected strains, identified the most effective non-contact antagonist, reducing pathogen colony diameter by 14. 3% at 7 days post-inoculation (dpi), with some strains achieving approximately 12–14% inhibition. F. vesca genotypes were evaluated using detached leaf assays at 4 and 7 dpi. Significant variation in disease severity was observed, with resistant genotypes maintaining lesion coverage below 0.6% at 4 dpi. The scientific importance of this study lies in its scale, ecological approach, and integration of mechanisms. By sourcing A. pullulans from wild F. vesca, the research explicitly addresses co-adaptation and compatibility between host and microbiome, providing a foundation for durable performance in the field. Overall, these results demonstrate that combining resistant F. vesca genotypes with elite A. pullulans strains can reduce dependence on chemical fungicides, aligning with EU Farm-to-Fork sustainability targets and offering a resilient strategy for both pre- and post-harvest control of anthracnose. This research enhances scientific understanding of biodiversity-based plant protection and establishes a framework for future biocontrol-breeding integration in strawberries and other perennial fruit crops.