Inhibitory Effects of 7 fungicides on Alternaria solani and their Field Efficacy

[methods] The inhibitory activity of 7 fungicides against Alternaria solani causing potato early blight was determined by the mycelial growth rate test.[Results] The results showed that the inhibition activity(EC50 0.238 mg/L) of mixture of azoxystrobin and difenoconazole(8:5,w/w)to mycelial growth is much stronger than the other 6 fungicides and obvious synergistic effects exist between azoxystrobin and difenoconazole.The results of field trials on controlling efficacy showed that after 7 d after 4 applications,azoxystrobin·difenoconazole 32.5% SC exhibied significantly higher controlling efficacy(95.33%) against potato early blight than the other fungicides.[Conclusions] The mixture of azoxystrobin and difenoconazole among 7 kinds of fungicides had a better control effect on the potato early blight,and can be selected preferably to control potato early blight.