Indoor Bioassay and Screening of Medicaments against Ustilaginoidea virens in Rice

[Objective] The research aimed to screen out the bactericides that could control Ustilaginoidea virens in rice effectively.[Method] The toxicities of bactericides including diniconazole,propiconazole and prochloraz to U.virens were determined respectively by the determination method of mycelium growth rate.And the regression equations of their toxicities were calculated by using least square method.[Result] The toxicity equation of diniconazole to U.virens was Y=0.331 4X+5.946 5(R2=0.941 8)and the EC50 value of diniconazole to U.virens was calculated as 0.06 μg/ml.The toxicity equation of propiconazole to U.virens was Y=0.489X+6.175 1(R2=0.982 4) and the EC50 value of propiconazole to U.virens was calculated as 0.09 μg/ml.The toxicity equation of prochloraz to U.virens was Y=0.116 3X+5.032 1(R2=0.99) and the EC50 value of prochloraz to U.virens was calculated as 0.76 μg/ml.[Conclusion] The toxicity of diniconazole to U.virens was highest,followed by propiconazole and that of prochloraz was lowest.