Baseline Sensitivity of Botrytis cinerea Isolates from Raspberry to a Novel Fungicide Fluopyram

The present study was conducted to evaluate the sensitivity to fluopyram of B. cinerea isolates from wild type population derived from raspberry. The initial isolation was done from infected raspberry fruits originating from a field which had never been treated with any pesticides. Twenty six B. cinerea single spore isolates were obtained and identified based on colonial and conidial morphology. Sensitivity of the isolates to fluopyram was determined in radial growth experiment on PDA medium supplemented with a range of fungicide concentrations. Mycelial growth on fungicide-amended media was presented as percentage of the control. The fungicide concentration that inhibited mycelial growth by 50% (EC-50) compared to the control was calculated using probit analysis. The results showed that the sensitivity to fluopyram of B. cinerea isolates from a wild type population, based on EC-50 values, ranged from 0.017 to 6.70 mg/L. These data will serve as a baseline to which any future B. cinerea sensitivity data can be compared to reveal any possible shifts in pathogen population regarding sensitivity to fluopyram.