Abstract: To clarify the pathogen species causing potato blackleg disease in winter-planted potatoes in Xiapu County and screen efficient, safe seed dressing agents, providing a scientific basis for local disease prevention and control. From 2023 to 2024, systematic field sampling was conducted on infected potato plants with blackleg symptoms in Xiapu County. Pathogen isolation and purification were performed using tissue separation methods, followed by pathogen identification through pathogenicity tests and 16S rDNA sequence analysis. Concurrently, during the 2024–2025 production season, field efficacy trials were carried out using Minshu No. 1 as the test material. Treatments included seed dressing with 3% zhongshengmycin（T1）, 46% copper hydroxide（T2）, 2% kasugamycin（T3）, 20% thiodiazole copper（T4）, 2×10^9 CFU·g⁻¹ bacillus subtilis（T5）, 5×10^9 CFU·g⁻¹ bacillus amyloliquefaciens（T6）, and distilled water as the control（CK）. The effects of these treatments on disease control efficacy, yield, and marketable tuber rate were evaluated. Field survey results indicated that typical symptoms of potato blackleg included leaf yellowing, curling, and dark brown discoloration at the stem base. The pathogen formed milky white colonies, which were circular or nearly circular. Pathogen identification revealed that the disease in Xiapu County was caused by composite infection of Pectobacterium carotovorum, Pectobacterium atrosepticum, Pectobacterium brasiliense, and Pectobacterium polaris, among which P. brasiliense was the dominant species. Field trials demonstrated that all seed dressing treatments had higher seedling emergence rates than CK（89.21%）, ranging from 93.57% to 97.60%. At the full seedling stage and budding stage, T6 exhibited the best control efficacy（70.15% and 67.19%, respectively）, followed by T5（65.67% and 65.17%, respectively）. In terms of yield, T6 achieved the highest yield（38,453.94 kg·hm⁻²）, representing a 38.54% increase compared to CK, with a marketable tuber rate of 91.70%. T5 ranked second with a yield of 37,682.02 kg·hm⁻², a 35.76% increase over CK, and a marketable tuber rate of 89.77%, both significantly outperforming CK and other chemical treatments. Seed dressing with 5×10^9 CFU·g⁻¹ Bacillus amyloliquefaciens and 2×10^9 CFU·g⁻¹ Bacillus subtilis showed excellent efficacy against potato blackleg disease, significantly improving seedling emergence rate, yield, and marketable tuber rate, making them suitable for promotion in production.