Sensitivity of Botrytis cinerea to fenpyrazamine in Japan and its disease control efficacy against the low-sensitive isolate

The baseline sensitivity of Botrytis cinerea to fenpyrazamine was evaluated using 323 isolates collected in Japan prior to its launch. In this study, the isolates were classified as "sensitive" and "low-sensitive" according to their mycelial growth on 10 mg/L fenpyrazamine. However, their EC50 values for the germ-tube elongations from conidia were not significantly different between these two classes. In both a pot test and a field trial, diseases caused by the sensitive and low-sensitive isolates were effectively controlled by fenpyrazamine.