[Objective]It aimed to investigate the fungicides with good inhibitory effect on sorghum anthracnose and the combination of compound agents with significant synergistic effect,which provided scientific basis for field control of sorghum anthracnose.[Method]The inhibition rate and EC50 of 6 fungicides(tebuconazole,prochloraz,pyraclostrobin,trifloxystrobin,iprodione and thifluzamide)against sorghum anthracnose at different concentrations were determined by mycelial growth rate method.According to the determination results,two fungicides with higher activity were selected and compounded in different proportions.The inhibition rate,EC50,co-toxicity coefficient(CTC)and joint toxicity of the compound on sorghum anthracnose were determined to evaluate their synergistic effects and explore the best compound ratio.[Result]The six fungicides had different degrees of inhibitory effect on sorghum anthracnose.Among the tested fungicides,97%prochloraz TC had the best inhibitory effect on sorghum anthracnose,with EC50 values of 0.002 1 mg/L,followed by 98%pyraclostrobin TC,with EC50 values of 0.610 3 mg/L,respectively.When the ratio of prochloraz and pyraclostrobin was 9:1,the inhibition effect was the best,as the EC50 value was 0.001 5 mg/L and CTC was 155.49.When the compounding ratio was 1:3,the synergistic effect was the best,as the EC50 value was 0.003 6 mg/L and CTC was 230.95.[Conclusion]The synergistic effect was the best when the ratio of 97%prochloraz TC and 98%pyraclostrobin TC was 1:3,and the combination of agents with this ratio had good antibacterial activity,indicating that it could be applied in field control of sorghum anthracnose.
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