Sensitivity of Venturia nashicola to flusilazole and cross-resistance against diverse fungicides

The sensitivity of eighty-eight Venturia nashicola strains collected from four different regions in Hebei Province to flusilazole was tested by germ-tube length method,and the sensitivity of ten relatively sensitive strains and five relatively resistant strains to thiophanate-methyl,kresoxim- methyl,thiram and difenoconazole was also tested by the same method.The results showed that there were some differences among all the sensitivity with the mean EC50 value of(1.3821±0.9276)μg/mL. With a frequency of the sensitivity followed a normal distribution curve,the mean EC50 value of 75 strains collected from the field where EBIs fungicides had never been used was(1.1676±0.6128)μg/mL and the maximum was 16.91 times to the minimum,which could be regarded as the baseline sensitivity of V.nashicola to flusilazole for field resistance monitoring.The correlation between flusilazole and difenoconazole was significantly positive,but there was no cross-resistance with other three different fungicides.