Examination of Rice Blast Incidence and Severity Caused by <i>Magnaporthe oryzae</i> ( <i>M. oryzae</i> ) in Tanzania Selected Rice Growing Regions

Abstract

Rice blast disease, caused by Magnaporthe oryzae ( M. oryzae ) is one of the most devastating diseases in rice production worldwide, causing high yield losses. In Tanzania, the disease exhibits significant impacts, largely due to limited diagnostic knowledge, resistant varieties, and poor control measures. This research study carried out during 2024/2025 aim to determine the incidence and severity of the disease across five representative rice-growing regions (Morogoro, Tanga, Kilimanjaro, Mwanza, and Mbeya). Disease incidence and severity from selected hundred (100) rice rice-growing farms were studied and recorded, while the symptomatic blast leaves were collected for isolation and morphological identification of the pathogen. The results revealed that both incidence and severity across regions, villages varied significantly at P &lt; 0.05 given that, Morogoro region showed the highest incidence (60.68% and severity (66.32%), and the lowest in Mwanza (46.52%, 51.95%). The study also detected Dakawa village has attacked more (61.29%), while Mvumi both from Morogoro was more infested (68.38%). Rice cultivars showed the significant differences in disease susceptibility levels, given that the variety TXD 306 (Saro 5) was relatively tolerant, with low incidence and severity (40.33%, 44.84%), whereas kalamata was highly susceptible (62.15% incidence and 67.71% severity). The noted significant regional difference (P&lt;0.001) in disease pressure from the studied region could be influenced by different climatic factors, ecology, and varieties grown. Overall, this finding highlights the significant threat posed by rice blast disease in Tanzania and suggests an urgent need for modern management measures and the adoption of resistant rice varieties.