Microbiomic Insights into Differential Snow Mold Severity in Winter Cereal Crops

Winter cereals, which are vital for global food security in temperate regions, face severe challenges during overwintering due to the development of snow mold—a complex disease caused by different microorganisms that combine phytopathogenicity with cold tolerance. Even within a single field plot, individual plants exhibit significant variation in snow mold severity. This natural variation was exploited to achieve the aim of the present study—the comparison of microbiomes of healthy and diseased plants of winter cereal crops (rye, triticale, and wheat) at the peak of snow mold manifestation to interpret differential disease severity through differences in plant-associated microbial communities and to obtain information necessary for the biological control of snow mold. Fungi of the genus Herpotrichia were implicated as novel candidate causal agents of snow mold in winter cereals. Variations in snow mold severity defy simple explanations tied solely to pathogen abundance or broad changes in overall microbial community composition. Instead, the most striking contrast between healthy and diseased plants was observed in the inferred candidate hub taxa, accompanied by marked changes in exploratory co-occurrence networks involving the candidate snow mold pathogens. These network alterations were crop-specific. Several key taxa were implicated as probable influencers of snow mold dynamics.