Changes in Sensitivity Levels of Botrytis spp. Population Isolated from Lily to Fungicides and Control under Field Condition

Forty eight isolates of Botrytis elliptica and 23 isolates of B. cinerea from several locations in Korea were testedfor resistance to fungicides used in the farmer's fields. Isolation frequency of B. elliptica having EC50 (effectiveconcentration of 50%) value 500 1000 μg/ml to benomyl and mancozeb appeared highly, suggesting that thetwo fungicides are not effective in controlling leaf blight of lily in the field. The isolates were tested forresistance to fungicides procymidone and iprodione which were most commonly used in the farmer's fields.The rates of EC50 value 5 50 μg/ml to procymidome and iprodione were 93.7% and 100%, respectively, andthose of 0 0.1 μg/ml to diethofencarb+carbendazim and fludioxonil were 98.0% and 93.8%, respectively. Inthe rain-protected cultivation, control of leaf blight of lily was the most effective when iprodine,diethofencarb+ carbendazim, and fludioxonil were sprayed alternately four times during the growing season.