Baseline sensitivity of Alternaria solani to iprodione andcharacteristics of the resistant mutants

The sensitivity of 42 strains of Alternaria solani collected from Wuzhai in Shanxi Province to iprodione was measured.The results showed that EC50 values of different strains of A.solani varied from 1.225 μ g/mL to 2.674 μ g/mL with the mean value of 2.556 μ g/mL,which could be regarded as the baseline sensitivity of A.solina to iprodione because the 42 strains were collected from the field where iprodione were never applied.To evaluate the resistant risk of A.solina to iprodione,21 iprodione-resistant mutants were induced by UV irradiation and 10 generation fungicide adaption in laboratory,and the characteristics of resistant mutants and sensitive strains were measured.The results showed that EC50 values of mutants were more than 100 μ g/mL which were high resistance level.And the resistance obtained was stable.Compared with sensitive strains,the mycelium growth and pathogenicity,especially the competition ability of the mutants were declined.However,the sporulation and germination were similar with that of the sensitive ones.