Detection of Resistance of Botryotinia fuckeliana from Protected Vegetables to Different Classes of Fungicides

For understanding the status of fungicide resistance in Botryotinia fuckeliana of protected vegetables,the sensitivities of 144 isolates collected from Zhejiang,Jiangsu,Liaoning and Shandong during 20052006 to six fungicides were evaluated.Results showed that low-level of resistance to chlorothalonil emerged with a frequency of 5.56%.Serious resistance of B.fuckeliana to carbendazim was detected with a frequency of highly-resistant sub-population of 27.08% and total resistance frequencyof 43.05%.Meanwhile,medium effective concentrations(EC50) of inhibiting radial growth for diethofencarb ranged from 0.137 μg/mL to 728.9 μg/mL with a mean value of(40.06 μg/mL).Frequency of double-resistance to carbendazim and diethofencarb was as high as(36.11%.) Meanwhile,two new phenotypes of double-resistance were reported.Only low-level resistance to iprodione or procymidone with frequency of about 20% was detected and no highly resistant isolates were detected although the dicarboximides had been used in practice for about 20 years in China.Moreover, resistance to pyrimethanil occurred with a frequency of 4.16% just a few years after its application in the sampled regions.The results indicated that serious and complex resistance problem to the six fungicides had emerged in B.fuckeliana of protected vegetables.