Screening of antifungal activity on nine phytopathogenic fungi of five sterol biosynthesis inhibitors (SBIs) antifungal agents

In order to discover efficient, low toxicity and environmentally friendly pesticide lead compounds, the inhibitory effects of five sterol biosynthesis inhibitors (SBIs) antifungal drugs (econazole, fluconazole, voriconazole, ketoconazole and miconazole) against seven plant pathogens were determined by mycelial growth rate method. After the preliminarily screening, effective fungicides were further tested in greenhouse and in field. The results showed that voriconazole had the highest fungicidal activities against the seven plant pathogens, and its EC₅₀ values were lower than 0.349 mg/L. Miconazole exhibited potent fungicidal activities against Fusahum graminearum, Alternaria kikuchiana, Fusarium oxysporum and Glomerella cingulata. Econazole showed strong fungicidal activities against A. kikuchiana and F. oxysporum, ketoconazole displayed excellent fungicidal activities against Magnaporthe oryzae. Both their EC₅₀ value were higher than that of difenoconazole against the corresponding plant pathogens. In greenhouse, voriconazole and fluconazole showed excellent inhibitory effects against wheat powdery mildew with the control efficiencies of 98.26% and 89.11%, respectively, at the dosage of 37.5 mg/L, which were higher than that of the commercial fungicide triadimenol. At the dosage of 150 mg/L, econazole showed strong inhibitory effect against rice sheath blight with the control efficiency of 86.14%. In the field trial, the control efficiency of fluconazole against wheat stripe rust was 98.42%, and the control efficacy of econazole against rice sheath blight was 75.21% at the dose of 240 g a.i./hm². Fluconazole, voriconazole and econazole exhibited potent fungicidal activities against the tested plant pathogens, which can be used as lead compounds for agricultural fungicides.