Fungicidal Management of Sheath Rot (Sarocladium oryzae) Disease on Rice Production in Guyana and Assessment of Socio- Economic Benefits.

Abstract

Sheath rot caused by Sarocladium oryzae (Sawada), is a major disease of rice that can significantly reduce grain yield and quality, resulting in economic losses for farmers. This study evaluated the efficacy of selected fungicides for the management of sheath rot disease under field conditions in Guyana and also assessed the potential socio-economic benefits. Three field trials were conducted during the Spring and Autumn cropping seasons of 2022 and the Spring cropping season of 2024 at the Plant Pathology Department Experimental Area, Guyana Rice Development Board (GRDB), Rice Research Station (RRS), Burma. The experiments were established using a Randomized Complete Block Design (RCBD) with four replications per treatment. The rice variety GRDB 14 was grown under recommended agronomic practices, and fungicides were applied at their respective rates. Results from the three trials demonstrated that most fungicidal treatments reduced sheath rot disease severity and improved growth and yield parameters compared with untreated control. The most effective treatments were Top Cop at 250 ml/ac, Onix at 350 ml/ac, Curacarb at 250 ml/ac, Saaf at 300 g/ac, and the positive check, Fugi One at 300 ml/ac, which reduced disease severity by 68.00–76.00% relative to the untreated control. Other treatments also reduced disease severity by 31.99–48.00%. Yield responses were mostly positive across the trials, with increases ranging from 2.23–34.23% in Spring 2022, 8.69–90.98% in Autumn 2022, and 3.31–70.43% in Spring 2024 over the untreated control. The reduction in disease severity and some levels of increase in grain yield indicate that effective fungicide use can enhance rice productivity and profitability. In general, increased yields can improve the overall farm income, strengthen household livelihoods, and contribute slowly towards reduction of poverty leading to greater economic returns. Furthermore, improved productivity supports sustainable rice production, enhances food security, and allows for benefits to stakeholders throughout Guyana’s rice value chain. Based on the consistent performance of Top Cop at 250 ml/ac, Onix at 350 ml/ac, Curacarb at 250 ml/ac, Saaf at 300 g/ac, and the positive check, Fugi One at 300 ml/ac are recommended for the management of sheath rot disease, particularly in areas where the disease is most prevalent.