Study on Pathogen Identification and Biocontrol Fungi Screening of Oat Sheath Rot

Oat sheath rot disease significantly reduces commercial oat yields, yet research on its incidence, causative pathogens, and control strategies remains limited, particularly in China. This study investigated the occurrence of oat sheath rot in major oat-producing regions of Northern China. Here, we isolated and identified two species of primary pathogenic fungi, Scopulariopsis brevicaulis and Alternaria alternata. Next, we conducted pathogenicity tests to confirm their role in the progression of oat sheath rot disease. Subsequently, we screened putative biocontrol fungi and identified Trichoderma harzianum and Trichoderma koningii as effective antagonistic biocontrol fungi. Both species demonstrated strong inhibitory effects against two primary pathogens through competitive interactions, with T. koningii achieving 100% inhibition in one test. Overall, T. harzianum and T. koningii both exerted strong inhibitory effects against pathogenic fungi via different forms of competition. Most importantly, infection experiments showed that T. harzianum and T. koningii both exerted strong antifungal effects against the pathogenic fungi that cause oat sheath rot. Taken together, our findings provide a foundation for developing biological control strategies to mitigate oat sheath rot in oat cultivation in China.