MULTIPLE FUNGICIDE RESISTANCE TO BENZIMIDAZOLES, DICARBOXIMIDES AND DIETHOFENCARB IN FIELD ISOLATES OF BOTRYTIS-CINEREA IN ISRAEL

During the period January-March 1989, 15 greenhouses at 12 sites in Israel were surveyed for the presence of fungicide-resistant strains of Botrytis cinerea, using a fungicide-amended Botrytis-selective medium. Resistance to benzimidazoles (Ben(R)) and to dicarboximides (Dic(R)) was frequent in most sites. Resistance to carbendazim + diethofencarb (Ben(R) NPC(R)) was found in all eight sites in which a mixture of these fungicides had been used against grey mould, but not in other sites. A new phenotype of multiple fungicide resistance was found among these isolates. The new phenotype, designated Ben(R) Dic(R) NPC(R), combines the three previously described characteristics of resistance to benzimidazole, dicarboximide and N-phenylcarbamate fungicides. It was found only in cucumber greenhouses that had been sprayed with the fungicide mixture carbendazim + diethofencarb against grey mould. Isolates of this phenotype were pathogenic in artificial inoculation of cucumber cotyledons treated with carbendazim, iprodione or carbendazim + diethofencarb.