Microbial agents suppress jujube black spot disease and enhance jujube quality by regulating soil physicochemical and microbial properties.

BACKGROUND Jujube black spot disease, caused by the soil-borne pathogenic fungus Alternaria alternata, threatens the sustainability of the jujube industry by adversely affecting yield. However, it is unclear whether microbial agents can increase yield by improving soil, inhibiting jujube black spots, and regulating microbial communities. RESULTS Bacillus velezensis strain SDTB038 had significant inhibitory effects on A. alternata, and sound field control effects (the control effects after two applications were 39.71% and 41.97%). SDTB038 had good saline-alkali tolerance and grew well in Potato Dextrose Broth medium containing 1%-7% NaCl or over pH range of 4-10. Upon application of B-1, multiple soil parameters were significantly improved, including levels of soil organic matter, total nitrogen and available potassium, and the activities of soil urease, alkaline phosphatase, catalase and sucrase. In a Tai'an jujube orchard, soil organic matter reached 16.54 g/kg, soil organic carbon 28.51 g/kg, and total nitrogen content 1.93 g/kg, consistent with the data trend in the Kashi area. Furthermore, applying B-1 resulted in a more complex interaction network among soil microorganisms. B-1 promoted the enrichment of beneficial microorganisms such as Bacillus spp. and Sphingomonas spp., while significantly reducing Alternaria spp. and Fusarium spp. levels. This increased jujube yield and overall quality (single fruit weight increased by 1.22-1.72 times). CONCLUSION This study fills a gap in current research on the application of microbial agents to prevent and control of jujube diseases, and has important theoretical and practical significance. © 2025 Society of Chemical Industry.