Sensitivisty of Penicillium digitatum in Zhejiang to the Strobilurin Fungicide Azoxystrobin

Sixty-five isolates of Penicillium digitatum were collected from Quzhou,Hangzhou,Jinhua and Lishui in Zhejiang Province during 2000 to 2006,where strobilurin fungicide azoxystrobin had never been used to control green mold of postharvest citrus.The sensitivities of the isolates to azoxystrobin were assayed by the methods of conidial germination and mycelial linear growth.The results demonstrated that the EC50 values for conidial germination and mycelial growth ranged from 0.020 1 to 0.260 0 μg/mL and 0.005 3 to 0.079 4 μg/mL,and averaged 0.042 6 and 0.0250 μg/mL,respectively.The frequency distributions of EC50 values of the 65 isolates were normally distributed for both conidial germination and mycelial growth.Thus,the mean EC50 values 0.042 6±0.030 4 and 0.025 0±0.012 9 μg/mL of the 65 isolates could be used as the sensitivity baselines for conidial germination and mycelial growth of P.digitatum to azoxystrobin,respectively.