Management of Sheath Blight Disease of Rice through Resistance Sources and Application of Fungicides

Sheath blight (ShB) is an important fungal disease of rice caused by Rhizoctonia solani. Worldwide distribution of disease and its soil borne nature has made its control challenging. The pathogen is responsible for yield loss up to 45%. In Pakistan, ShB has been observed in the major rice growing areas with higher severity on cultivated rice varieties. The most probable reasons of increasing magnitude of the sheath blight disease are the changing climatic conditions, suspended cultivation practices and reduced varietal diversity. The disease scenario demands to formulate the integrated management strategies under changing climatic conditions. Use of resistant varieties is the most reliable, economical and efficient strategy to manage this disease. To identify the resistance sources, local and exotic advanced rice germplasm was evaluated using artificial inoculation of R. solani. The data was recorded after three weeks of inoculation using standard disease rating scale. Among eighty five varieties/lines, Noor Basmati (15.49% Disease severity) and IRRI-29 (19.18%) were found resistant. Eight varieties/lines were moderately resistant while rest of the varieties/lines showed susceptible response against sheath blight disease. In addition to disease screening, effective fungicides against sheath blight disease was also identified. For this, nine fungicides were tested in lab and field conditions. In-vitro assay revealed that Amistar Top, Tilt, Top Guard, Nativo, Topsin-M and Kachaloo completely (100%) inhibited the mycelial growth of R. solani. Under field conditions, Kachaloo followed by Topsin-M, Argyl Super and Nativo were found most effective in disease control. The findings of the present studies would help in the development of disease resistant rice varieties and application of suitable fungicides for the management of sheath blight disease.