Prevalence of Bean Root Rot Pathogens in Tharaka Nithi County, Kenya

Kenya is among the top common bean producing countries globally with an annual production of 0.76 million tonnes worth Ksh. 60 billion. However, its production faces several biotic and abiotic challenges. Among these challenges is the root rot disease, which causes an estimated yield loss of 70% every year. The disease is caused by several soilborne pathogens, making it difficult to control through use of cultural practices, chemicals and development of tolerant varieties. This study was carried out in five bean growing agroecological zones in Tharaka Nithi County, Kenya during the long rains season (March to April) of 2023. The aim of the study was to determine the prevalence of the root rot disease pathogens in different agroecological zones in the county. A descriptive survey design was used to collect data on prevalence of the disease in farms. Analysis of variance was used to determine if there were significant differences in prevalence between different agro-ecological zones. Further the significant means were separated using Least Significant Difference at α = 0.05. The findings of the study showed that bean root rot disease was caused by four main soilborne microorganisms including Fusarium, Macrophomina, Pythium and Rhizoctonia spp which occurred in all agroecological zones of the county. The highest disease prevalence (37.58%) was in AEZ UM3 followed by LM4 (34.17%), LM5 (20.63%), UM2 (18.2%) and UM1 (16.76%) respectively. Additionally, the prevalence of the disease pathogens varied significantly (p < 0.05) across the agroecological zones in the county. Therefore, appropriate measures should be employed to control and reduce yield loss associated with the disease.