Laboratory Toxicity Tests of Seven Fungicides and Their Mixtures on Alternaria solani

In laboratory, the toxicity effects of seven commercial fungicides including Procymidone etc and their mixtures which had better preventive efficiency on Alternaria Salani were determined by measuring mycelial growth rate were teste. The results showed that each fungicide has obvious inhibitory effect on mycelial growth of Alternaria Salani. In a wide range of fungicide concentrations(0.01~5.00 mg / L),the inhibition ratio of Iprodione,Chlorobromoisocyanuric acid,Propineb, Difenoconazole,Kresoxim-methyl, Alkyl nitriles methoxy quinone and Procymidone single agent were 76.15% ~100% 、8.76% ~17.97% 、2.01% ~70.92%、71.82%~100%、51.35%~71.59%、42.46%~93.87%、32.16%~91.76%;The EC50 values were 0.033 52、77.886 50、2.268 14、0.723 80、0.049 56、0.018 972、0.018 175 mg / L;The mixtures of Iprodione and Procymidone with ratio of 1 ∶1,Procymidone and Difenoconazole with ratio of 1∶2、2∶1,Procymidone and Kresoxim-methyl with ratio of 1∶1 、1∶2, Difenoconazole and Kresoxim-methy with ratio of 1∶1、1∶2、2∶1,Iprodione and Difenoconazole with ratio of 1∶2 have particularly obvious synergistic effect.The mixtures of Iprodione and Difenoconazole with ratio of 2 ∶1 have obvious synergistic effect;Iprodione and Procymidone have obvious synergistic effect 1∶1,Procymidone and Difenoconazole have obvious synergistic effect 1∶1,Iprodione and Difenoconazole with ratio of 1∶1 have slightly synergistic effect.