Sensitivity of Botrytis Cinerea Isolates Collected from Strawberry to Carbendazim, Diethofencarb and Iprodione

Currently strawberry is considered essential strategic crop in Egypt as it has great economic value. Grey mould disease, which caused mainly by Botrytis cinerea , is a serious disease significantly reduces strawberry production globally. Protective fungicides considered essential tool in management strategies. Recently, fungicides ineffectiveness observed widely in many countries. Therefore, this investigation carried out to test the sensitivity of 311 isolates of Botrytis cinerea collected between 2019 and 2021 from strawberry open fields in Egypt's major strawberry-producing governorates (Beheira, Ismailia, Qalyubie, and Dakahlia) to diethofencarb, iprodione and carbendazim. The isolates were tested to distinguish resistant isolates and determine the EC 50 values for sensitive and resistant isolates. The results showed that 7.4, 37.94 and 93.77% of the isolates found to be resistant to diethofencarb, iprodione and carbendazim, respectively. During the 2019 and 2021, resistance frequencies among B. cinerea isolates significantly increased, rising from 91.91% to 96% for carbendazim, from 10.29% to 16% for diethofencarb, and from 22.79% to 59% for iprodione. The mean EC 50 values for the sensitive isolates were 0.021, 0.027 and 0.0548µg/ml, while the mean EC 50 values for the resistant isolates were 141.06, 24.94 and 0.7161 µg/ml for carbendazim, diethofencarb and iprodione, respectively. There were little variations in osmotic sensitivity to NaCl between iprodione sensitive and resistant isolates. All carbendazim resistant isolates detected were sensitive to diethofencarb except three isolates showed dual resistance to diethofencarb and carbendazim.