Common bean ( Phaseolus vulgaris L.) plays a significant role in Tanzanian agriculture, sustaining food security and rural livelihoods for millions of smallholder farmers. However, its production is increasingly jeopardized by climate change and variability, most notably drought, heat stress, and flooding which has intensified both the frequency and severity of devastating diseases and insect pests. This systematic review, conducted in accordance with PRISMA 2020 guidelines, synthesizes findings from 103 peer-reviewed studies published between 2005 and 2025, drawing from leading scientific databases and institutional repositories focused on Tanzania. Results indicate that over 65% of documented disease outbreaks are attributable to climate extremes, which significantly influence pathogen virulence, life cycles, and host vulnerability. Drought was found to correlate with a 30–50% increase in wilt disease incidence, while heat waves accelerated disease progression in approximately one-third of cases with estimated yield loss of up to 40% by 2050. Flooding, though less frequently addressed, was identified as an emerging and insufficiently studied factor in soil- and water-borne diseases. Breeding initiatives in Tanzania have advanced drought, heat tolerance and resistance to diseases, yet more than 70% of programs continue to focus on single-stress resistance, with limited integration of multi-stress or participatory approaches. The adoption of genomic-assisted selection methods remains promising within national breeding efforts. This review underscores the necessity of transitioning toward climate-smart breeding frameworks, integrating multi-stress resilience, robust disease surveillance, and participatory research to enhance the sustainability and productivity of common bean cultivation under changing climatic conditions.

This study examined the prevalence of seed-borne fungi in polyethylene plastic-packaged soybean seeds stored in a genebank and identified factors influencing their incidence. Twenty-four seed lots were sampled from the collection stored at 10 °C in the World Vegetable Center genebank in Arusha, Tanzania. The seeds used were those regenerated and harvested in 2015, 2016, and 2017. A seed health test was conducted for sterilized seeds on potato dextrose agar, sterilized seeds on top of the paper, and unsterilized seeds on top of the paper. Seven-year-old sterilized seeds plated on top of the paper exhibited the highest germination percentage (74 ± 7.09%) and lowest fungal incidence (7.00 ± 4.41%). Conversely, seven-year-old unsterilized seeds plated on top of the paper had the lowest germination (22.00 ± 6.97%) and highest fungal incidence (79.00 ± 8.31%). Older seed lots showed significantly higher equilibrium seed moisture content (Eqmc), though seed age had no significant influence on germination percentage or fungal incidence. Seed germination percentage showed a significant negative relationship with Eqmc, though Eqmc had no significant effect on fungal incidence. Meanwhile, germination percentage showed a significant negative relationship with fungal incidence. Six fungi isolates were identified using their morphological features from soybean seed samples: Absidia glauca, Aspergillus niger, Fusarium spp., Mucor hiemalis, Pestalotiopsis versicolor, and Sordaria macrospora. It is concluded that high fungal incidence negatively affects seed germination but is not significantly correlated with seed moisture content. The dry and cold storage conditions in the genebank, while effective in extending seed longevity, can unintentionally allow seed-borne mycoflora to persist. Although fungi may not actively proliferate under these conditions, they may do so when favorable conditions are restored, such as during germination tests, and consequently may compromise seed viability. Therefore, this study emphasizes the importance of increased systematic seed health checks before storage in genebanks to ensure optimal seed quality, and the replacement of all polyethylene plastic bags to aluminium foil packaging.