Study on fungicidal activity and mode of action of a novel fungicidal agent,LH-2010A against Rhoizoctonia solani

The mycelial linear growth rate method was adopted to determine the toxicity of LH-2010A to 10 pathogens,and the effects of LH-2010A on the process of asexual reproduction,membrane permeability and mycelial morphology of Rhizoctonia solani were also detected.The results indicated that LH-2010A had broader fungicidal spectrum than another formamide fungicide,fluopicolide with effective activity against 10 pathogens.The highest toxicity of LH-2010A to R.solani and Botrytis cinerea were obtained with EC50 value less than 1.00 μg/mL,while the eight others with EC50 1.10-4.63 μg/mL.However,fluopicolide only exhibited high toxicity to Phytophthora capsici and Phytophthora infestans with EC50 values as 0.61 μg/mL and 0.72 μg/mL,respectively.In addition,LH-2010A had high fungicidal activity against sclerotinia and mycelial growth of R.solani,and it only showed inhibitory effect on R.solani at concentration less than 100.0 mg/L.Moreover,the amount of ramification increased and the mycelium formed irregular ramification or abnormal configuration (contracted or swelled up) on mycelium tip.With the increase of LH-2010A concentration,the membrane permeability of R.solani increased,and the highest relative leakage reached 77.01% at 520 min.In conclution,LH-2010A has high fungicidal activity against various pathogens and it can inhibit some physiological characteristics of R.solani.