Determination and Analyses of Sensitivity to Azoxystrobin of Alternaria solani from Potato in the Northern Hebei Province

Seventy-four isolates of Alternaria solani were collected from Zhangjiakou and Chengde in Hebei province from2009 to 2011.Sensitivity to azoxystrobin was determined with inhibition of conidial germination methods to provide theoretical basis for the scientific use of azoxystrobin.The results showed that the EC50 values were in the range of 0.01~0.13 μg/m L.The mean of the EC50 value was 0.04 μg/m L.87.84% of the total strain was sensitive(EC50values were in the range of0.01~0.07 μg/m L).Strains with azoxystrobin sensitivity decreased slightly year by year.There were differences in sensitivity of azoxystrobin for the strains collected in different regions.Prevention and control of potato early blight can still use azoxystrobin in northern Hebei Province.It is advised not to use blindly and to detect strains of drug-resistant of azoxystrobin at any time.