Acquisition of fungicide-resistance by the sensitive strain contact-cultured with dicarboximide fungicide-resistant strains of Botrytis cinerea.

Abstract

Mycelial disks of benomyl-and dicarboximide fungicide-resistant strain (CAES-4), benomyl-resistant strain (CAES-7), dicarboximide fungicide-resistant strain (CAES-2) or sensitive strain (CAES-5) of Botrytis cinerea were contact-cultured in the center of colony of sensitive strain (IPCR-1). Mycelial disks collected from the colony of IPCR-1 were placed on PSA media containing fungicides. In contact-culture with CAES-4, four resistant strains (IC4-4B, -4I, -4P and -4V) developed from IPCR-1 colony. IC4-4B, -4I and -4V, which were resistant to both benomyl and dicarboximide fungicides, showed the same growth rate as that of CAES-4, but in colony forms or pathogenicity to cucumber, were similar to that of IPCR-1. IC4-4P was sensitive to benomyl, and different from the parent strains in the properties. In contact-culture with CAES-7, three resistant strains (IC7-4B, -2P and -4P) were obtained. IC7-4B was nearly similar to CAES-7 in the properties. IC7-2P and -4P showed higher MIC of dicarboximide fungicides than that of CAES-7, although the value of benomyl was nearly the same as that of IPCR-1. IC2-4P, which was obtained by contact-culture with CAES-2, showed the same properties as those of CAES-2, except a higher pathogenicity as compared with those of parent strains.