Farmers perceptions, climate change and influence of disease dynamics on common beans production in Tanzania

Common bean ( Phaseolus vulgaris L.) is a cornerstone of food security and income for smallholder farmers in Tanzania. However, increasing climate change and variability is intensifying disease pressures which in turn challenge sustainable production. This study assessed the current status of climate change and spectrum of common bean diseases across five Tanzania’s major production zones through field surveys and farmer interviews. Standardized visual diagnostics were performed at multiple crop growth stages, with 10 fields sampled per district from 11 districts and 50 plants assessed per field. A total of 301 farmers were interviewed regarding seed sources, cropping practices, disease management strategies and climatic influences on diseases’ pressure. Overall, results revealed Angular Leaf Spot (ALS) as the most prevalent disease, accounting for 30.2% of all disease observed followed by Bean Common Mosaic Virus (BCMV) at 27.7%, Common Bacterial Blight (CBB) at 11.7%, anthracnose at 10.3%, and bean rust at 9.8%, with other diseases collectively comprising less than 4.6%. Disease prevalence and composition varied significantly by agro-ecological zones and districts (p 0.001), with ALS dominating in the Lake, Northern, and Southern Highlands zones, a more balanced disease profile in the Western zone, and a virus dominated profile in the Eastern zone. Seasonal variations and crop phenological stage were significantly associated with disease incidence, notably with late season increases in ALS which is linked to prolonged leaf wetness periods. Cropping systems influence disease patterns, with intercropping favoring BCMV, while monocropping and mixed systems are primarily dominated by ALS. Farmers primarily rely on chemical controls (71.8%), with crop rotation, shifting cultivation, intercropping, and resistant varieties. Most respondents recognized climate change signals leads to disease dynamics, and weather-related disease reports also varied by zone. The findings highlight the complex interplay between local climate, canopy microclimate, seed systems, and management practices in shaping bean disease risks. The study emphasizes the need for integrated, zone specific disease management strategies like early ALS and BCMV intervention, such as use of resistant varieties, use of quality seeds, and adaptive decision support tools to enhance yield stability under changing climatic conditions.