关键词: 甘薯黑斑病, 甲基硫菌灵, 咯菌腈, 杀菌剂, 浸苗, 薯块, 农药残留

Abstract: To explore the feasibility of controlling black rot of sweet potato during the harvest and storage periods by dipping seedlings with fungicides，the inhibitory effects of dipping seedlings with thiophanate‐methyl and fludioxonil on disease occurrence at the base of main stems and storage roots were evaluated under soil or seedlings inoculation conditions. This control efficacy was compared with that of the treatment of dipping both seedlings and storage roots.The results showed that under soil inoculation conditions，the control efficacy on black rot of sweet potato could reach 71.04%—87.57% for base of main stems，and 57.80%—73.84% for storage，by dipping seedlings with 500 g/L thiophanate‐methyl SC at 500，600 mg/L，or with 50% fludioxonil WP at 250，500 mg/L.For the same fungicides and concentrations，there was no significant difference in the control efficacy between the treatments of dipping seedlings alone and dipping both seedlings and storage roots with thiophanate‐methyl or fludioxonil，while increasing the concentration could improve the control efficacy.At 58 days of storage，the control efficacy of dipping seedlings with 500 mg/L thiophanate‐methyl SC was 62.56%—63.47%，and that with 500 mg/L fludioxonil WP was 66.53%—72.57% when seedlings or soil were contaminated.At 102 days after dipping seedlings，thiophanate‐methyl and carbendazim were still detectable in the base of main stem，but not in the storage roots of sweet potato，while fludioxonil was not detected in either the base of main stems or the storage roots.In summary，dipping seedlings with thiophanate‐methyl and fludioxonil could effectively inhibit the occurrence of black rot of sweet potato during storage period.

Key words: Sweet potato black rot, Thiophanate‐methyl, Fludioxonil, Fungicide, Seedling dipping, Storage root, Pesticide residue