Pathogenic variability among Curvularia species causing brown leaf spot disease of rice

The brown leaf spot disease of rice, caused by Curvularia spp., results in yield losses of up to 90% in susceptible varieties and poor grain quality. Previously in Ghana, Curvularia lunata was identified as a pathogenic species to rice. In this study, five Curvularia species namely Curvularia soli, Curvularia lunata, Curvularia senegalensis, Curvularia subpapendorfii, and Curvularia geniculata isolated from diseased rice variety “AGRA” were assessed to determine potential variations in their pathogenicity using both detached leaves and whole plant assays arranged in a completely randomized design. The evaluation included an analysis of lesion sizes, disease incidence and severity, as well as the disease progression. Results indicated the pathogenicity of all the Curvularia species, with significant differences (P < 0.05) observed in lesion size, disease severity index, and disease incidence. Overall, C. lunata demonstrated high pathogenicity, producing the largest lesion size (5.5 cm) and the highest disease severity index (90.0%) in detached leaves and whole plant assays. In conclusion, it is evident that various Curvularia spp. causing leaf spot disease on rice variety “AGRA” exhibit differences in their level of pathogenicity. These findings should guide the development of management practices such as breeding for resistant rice varieties.