Abstract: 【Objective】 In peanut production area of China, disease of crown rot, root rot and Sclerotium blight commonly occurred and caused heavier damage in recent years. The objective of this study is to compare the toxicity of FS (flowable concentrate for seed treatment) and CS (microcapsule suspension) of difenoconazole and fluazinam to three peanut soil-borne fungi and definite the safety, control efficacies and application methods of two preparations of difenoconazole and fluazinam by seed-coating against three peanut soil-borne fungal diseases. 【Method】 Firstly, the toxicity of two preparations of difenoconazole and fluazinam to Aspergillus niger, Fusarium solani and Sclerotium rolfsii were determined. Then the safety of seed-coating of the two preparations of difenoconazole and fluazinam on peanut was evaluated. Finally, field trial was conducted in order to confirm their control efficacies. 【Result】 The EC₅₀ values of 6% difenoconazole FS, 15% difenoconazole CS, 50% fluazinam FS and 12% fluazinam CS in inhibiting A. niger were 0.0503, 0.4959, 5.6141 and 46.5433 mg?L^-1; in inhibiting F. solani were 0.5386, 2.8604, 0.3780 and 28.1665 mg?L^-1; in inhibiting S. rolfsii were 1.1435, 3.2615, 0.0951 and 3.8920 mg?L^-1, respectively. All the treatments exhibited no significant difference compared with control check about peanut emergence rate and time, root length and fresh weight, plant height, fresh weight of stem and leaf (in an incubator at 20℃ and 25℃). In the field trial, all the treatments exhibited no significant difference compared with control check about peanut emergence rate and time. The control efficacies of 6% difenoconazole FS and 15% difenoconazole CS at the rates of 100 and 200 g a.i./100 kg seed by seed-coating to the three peanut soil-borne fungal diseases were all higher than 68.03%. The control efficacies of 12% fluazinam CS at the rate of 160 g a.i./100 kg seed by seed-coating to the three peanut soil-borne fungal diseases were all higher than 74.97%, which were higher than the same dosages of 50% fluazinam FS. Pod yield of all treatments significantly increased compared with control check. The yield growth rate increase of 15% difenoconazole CS at the rate of 200 g a.i./100 kg seed treatment was higher, and ranged from 7.22% to 11.47%.【Conclusion】Difenoconazole 6% FS and 15% CS at the rates 100 and 200 g a.i./100 kg seed, and fluazinam 12% CS at the rate 160 g a.i./100 kg seed were all security to peanut and were high-efficient in controlling peanut crown rot, root rot and sclerotium blight by seed-coating treatment.

Key words: difenoconazole, fluazinam, seed-coating, peanut soil-borne fungal diseases, security, toxicity, control efficacy