Antifungal activity of the compound of triticonazole and phenamacril against Fusarium fujikuroi

In this study, the mycelial growth rate method was used to determine the antifungal activity of triticonazole against Fusarium fujikuroi, and the EC₅₀ values of triticonazole against 10 strains of F. fujikuroi ranged from 0.0664 μg/mL to 0.7661 μg/mL. After seed treatment with 60, 120, and 240 μg/mL active concentrations of 25 g/L triticonazole suspension concentrate, the germination rate, plant height, and fresh weight of rice were not affected. The results indicated that triticonazole not only has good antifungal activity against F. fujikuroi, but also has good security for rice, and can be used to control rice bakanae disease. The EC₅₀ values of phenamacril against 10 strains of F. fujikuroi ranged from 0.0076 to 0.2629 μg/mL. The joint toxicities of phenamacril and triticonazole at the ratios of 4 : 1, 3 : 1, 2 : 1, 1 : 1, 1 : 2, 1 : 3, and 1 : 4 against F. fujikuroi were determined. The result showed the synergistic ratio ranged from 0.5 to 1.5, indicating that the combinations of phenamacril and triticonazole exhibited an additive effect on the inhibition of F. fujikuroi mycelial growth. This study indicated the combinations of phenamacril and triticonazole not only decrease the use dosage of a single component significantly but also reduce the selective pressure of F. fujikuroi populations to phenamacril and delay the resistance development, ensuring the control efficacy of rice bakanae disease and safe production of rice.