Evaluation on Resistance of Grape Gray Mold Pathogen Botrytis cinerea to Pyrimethanil in China

Objective)The resistance to pyrimethanil of Botrytis cinerea isolated from diseased grape berries in China was studied. (Method)A total of 104 single conidial isolates of B. cinerea were isolated from diseased grape berries which were collected from vineyards located in 14 different cities or suburban counties in China. The method of mycelial growth inhibition was used to determine the resistance of B. cinerea to anilinopyrimidine fungicides pyrimethanil.(Result)The findings in the current work demonstrated that the resistance frequency of B. cinerea to pyrimethanil was 22.22% to 62.5%. Most of the resistant isolates showed middle resistant or high resistant phenotype, and the resistant frequency of high resistant isolates reached up to 44.23%. Resistance to pyrimethanil of B. cinerea differs in different viticulture climate zones. (Conclusion)Resistance to pyrimethanil of B. cinerea isolated from grape diseased samples in China is commonly present, and the resistant isolates showed cross resistance. Accordingly, the frequency of use of pyrimethanil should be limited in the prevention of grape gray mold, and fungicides such as dicarboximide and carbamates can be used alternatively. It was suggested that novel fungicides or biofungicides should be introduced for the control of grape gray mold.