Evaluation of the Incidence of Rice Blast Disease (Pyricularia oryzae) in Kebbi State, North West Nigeria

Rice blast, caused by Pyricularia oryzae, ranks among the most destructive fungal diseases threatening rice production globally and has been increasingly reported in Nigerian irrigated rice systems. This study evaluated the incidence and distribution of rice blast disease in lowland irrigated rice farms across three communities in Kebbi State, a key rice-producing state in Nigeria's North West zone. Field surveys were conducted during the 2023 and 2024 dry-season cultivation periods, covering 50 farms with a total of 200 observation plots. Characteristic lesions on leaves, collars, and panicles were recorded and scored using standard blast severity scales. Isolation and pathogenicity tests confirmed P. oryzae as the causative organism in all symptomatic samples examined. Disease incidence averaged 52 percent at the leaf blast stage and 38 percent at the neck and panicle blast stage, with yield losses estimated at between 20 and 35 percent in severely affected plots. Early-maturing varieties showed greater susceptibility compared to medium-duration varieties. Continuous planting of the same variety and high nitrogen application rates were noted as aggravating factors. These results align with recent literature documenting the expanding geographic range of virulent P. oryzae races in West Africa. The study recommends multi-location evaluation of blast-resistant varieties under Kebbi State growing conditions and revision of nitrogen management guidelines. Keywords: rice blast, Pyricularia oryzae, Kebbi State, disease incidence, irrigation.