Abstract
Sensitivity of bean gray mold fungus collected in several districts of Hokkaido to fluazinam and other botryticides was investigated. Three hundred and two isolates of Botrytis cinerea were obtained from diseased pods of kidney bean or adzuki bean collected in 1990 and 1991. Inhibition of mycelial growth on PSA medium and preventive activity on kidney bean of fluazinam, procymidone, thiophanate-methyl and diethofencarb were measured. Difference in sensitivity to fluazinam was not observed among isolates tested; EC95 value of mycelial growth inhibition and minimum effective concentration of preventive activity were less than 1ppm and less than 31ppm, respectively. There were considerable differences in the sensitivity to procymidone and thiophanate-methyl. Resistant isolates to procymidone and/or thiophanate-methyl which could cause the decrease of control efficacy at practical dosages existed. Furthermore, fluazinam showed high antifungal activity against isolates which were resistant to procymidone and/or thiophanate-methyl similarly as sensitive isolates. These findings suggest that fluazinam is effective against bean gray mold resistant to conventional botryticides.
