Abstract
Five isolates of S. cepivorum tolerant to 1 dicarboximide fungicide showed cross-tolerance to the dicarboximides iprodione, myclozolin and vinclozolin and to dicloran and PCNB [pentachloronitrobenzene] but not to benomyl, captan or thiram. The dicarboximides dicloran and PCNB share a common structural subunit. EC90 values for most tolerant isolates were > 1000 times those of the parent isolates. Sensitivity to benomyl was unchanged by tolerance to dicarboximides. Wide variations in sensitivity of the parent isolates to PCNB and thiram were noted. Frequency of occurrence of dicarboximide tolerance was too low and variable to obtain a reliable estimate.