Cutting regimes modulate foliar fungal diseases and seed pathogen incidence in Lolium multiflorum L.

In Southern Brazil, Lolium multiflorum is a crucial winter crop due to its nutritional properties for livestock and availability during periods of food shortage. However, fungal diseases like gray leaf spot (GLS), brown leaf spot (BLS), and rust (RU) threaten the crop yield. Adjusting cutting regimes is a low-cost disease management strategy. Nonetheless, its effects on foliar pathogens and subsequent seed contamination remain unclear. Therefore, this study assessed how different numbers of cuttings influence the progress of foliar diseases and the incidence of seed-borne fungi. In this sense, a randomized block design tested four treatments: uncut control (0C), one cutting (1C), two cuttings (2C), and three cuttings (3C). Foliar disease severity and incidence were monitored over 69 days. The area under the disease progress curve (AUDPC) was calculated for each disease. At harvest, seeds were analyzed using blotter tests to detect fungal contamination. The AUDPC for the 3-cutting treatment was reduced by 70% for GLS and 76% for RU compared with the no-cutting treatment. Saprophytic fungi (Alternaria spp., Cladosporium spp.) dominated seeds under high cutting regime (up to 86% incidence). Increasing the number of cuttings, from one to three cuttings, suppressed foliar diseases but shifted the seed-associated fungal community, such as Alternaria spp. Because increasing the number of cuttings alone cannot control this shift, integrated strategies are needed to balance both outcomes.