Antifungal Spectrum And Mechanism Of Action Of LH-2010A

LH-2010A is a novel formamide fungicide that synthesized in China. In order toconfirm its fungicidal spectrum, action mode and mechanism. Bioassay method was adopted todetermine LH-2010A’s toxicity to10pathogens, and identified its action mode to Phytophthoracapsici, effects on Rhizoctonia solani for the process of asexual reproduction, membranepermeability, respiratory metabolism and mycelial morphology were detected. The resultswere as follows:1. LH-2010A was effective in suppression of10pathogens with all EC50values less than5mg/L. The toxicity for Rhoizoctonia solani and Botrytis cinerea were the highest with EC50less than1mg/L, and the others were also very high with all EC501.095~4.633mg/L.Fluopicolide, another formamide fungicide, only had the high toxicity for Phytophthoracapsici and Phytophthora infestans with the EC500.614mg/L and0.719mg/L, respectively.Compared with fluopicolide, LH-2010A has higher toxicity and broader spectrum.2. LH-2010A exhibited significant protective and curative activity against Phytophthoracapsici. Moreover, the protective effect of LH-2010A showed relatively higher value (96.9%,100%) than the curative effect (72.8%,90.2%) at20mg/L and40mg/L. LH-2010A couldeffectively inhibit mycelial growth, cystospore germination and sporangia production withEC50values of3.023mg/L,0.666mg/L and0.529mg/L, respectively. The results indicatethat LH-2010A has protective and curative activity against Phytophthora capsici, and canapplied in each stage of Phytophthora blight.3. LH-2010A has high fungicidal activity to Rhizoctonia solani’s sclerotinia and myceliagrowth, and it only showed inhibited activity against Rhizoctonia solani at100mg/L.LH-2010A could inhibit Tricarboxylic acid cycle (TCA) and induce alternative oxidasepathway of Rhizoctonia solani, while lower inhibition of Hexose Monophophate Pathway(HMP). Under different concentrations of LH-2010A, the membrane permeability ofRhizoctonia solani had great changes, with the highest relative leakage77.005%. LH-2010Ahad significant inhibition effects on Rhizoctonia solani resulting in increased mycelial branchwith shorter and thicker, and scanning electron microscope indicated that LH-2010A couldeffect on Rhizoctonia solani’s cell wall in a certain extent. The result shows that the mechanism of LH-2010A is damaging the cell wall.