Synergistic and Field Effects of Thifluzamide and Fludioxonil against Rhizoctonia solani

[Aims] The paper aims to determine the best ratio for the mixture of thifluzamide and fludioxonil in management of rice sheath blight caused by Rhizoctonia solani. [Methods] Effects of the mixtures of thifluzamide and fludioxonil were tested in greenhouse, and the Sun-Johnson method was used to evaluate the synergistic effect of thifluzamide and fludioxonil against Rhizoctonia solan. [Results] The results showed that the mixtures of thifluzamide and fludioxonil at the ratios of 1:1 or 1:4 revealed significant synergistic effect with EC50 values of 13.74 and 13.9 mg/L, and the CTC values of 163.98 and 187.67, respectively. Considering the efficacy and cost, the mixture of thifluzamide and fludioxonil at the ratio of 1:1 was selected to make a formulation of 25% SC. The field efficacy of this mixture at 60 g a.i./ha was 90.6% against rice sheath blight, which is better than those of thifluzamide and jinggangmycin. [Conclusions] The mixture of thifluzamide and fludioxonil is excellent in controlling rice sheath blight, and could be used extensively.