Biocontrol Potential of dollar spot mycosphere bacteria

Dollar spot, caused by Clarireedia species, is a major turfgrass disease typically managed with frequent fungicide applications, raising concerns about resistance, environmental impact, and sustainability. This study explored microbial communities associated with Clarireedia mycelia and assessed the biocontrol potential of mycosphere-associated bacteria and yeasts. Amplicon sequencing revealed that the mycosphere was dominated by Proteobacteria, with contributions from Actinobacteria, Firmicutes, and Bacteroidetes varying across hosts and years, and Sphingomonas spp. consistently abundant. In total, 46 bacterial and six yeast strains were isolated, several of which strongly inhibited C. jacksonii and C. monteithiana in vitro and produced hydrolytic enzymes linked to antifungal activity. Two yeast isolates, Papiliotrema aspenensis and Rhodotorula glutinis, also showed notable antagonistic potential. Field trials confirmed that multiple mycosphere-derived bacterial strains significantly reduced dollar spot severity and performed comparably to some commercial biofungicides, highlighting their promise as sustainable biocontrol agents.