Field evaluation of some fungicides for controling sheath blight disease of rice in north of Iran

Sheath blight disease of rice caused by Rhizoctonia solani AG-1 IA has been recognized as an economically significant disease. No resistant cultivar has been reported so far, and rice ShB management has been mainly leaning on chemical fungicide applications. To prevent resistance to fungicides in pathogenic fungal strains, introducing new fungicides with different effect points and belongs to other groups is essential for integrated disease management. Thus, in 2019, the efficacy of the fungicide Thiflozamide 24% SC was studied on control of rice sheath blight disease in the north of Iran. A research project were designed with a randomized complete block design in three replications and 14 treatments by Thifluzamide, Nativo and Tilt fungicides. Six spray treatments were performed in one step, 24 hours after plant infestation with the casual agent. Another six spray  treatments were performed in two steps, 24 hours and 15 days after plant infestation with the casual agent. Eventually, the efficacy of treatments on relative lesion height (RLH), incidence, and grain yield were surveyed. Data were subjected to the analysis of variance (SAS, 2003). Means among the treatments were compared based on Tukey’s test at the 0.05 probability level. The results showed that one spraying step with Thifluzamide 24% SC fungicide (300 ml/ha dosage) is recommended for Guilan and Mazandaran provinces. If the conditions are suitable for the disease development, it is necessary to repeat the spraying with Thifluzamide 24% SC fungicide (300 ml/ha dosage) 15 days after the first spraying. In order to prevent the possibility of resistance, Nativo and Tilt fungicides are suggested as an alternative or intermittent use of Thifluzamide fungicide.