Fitness of Botrytis cinerea associated with dicarboximide resistance

Fitness costs in Botrytis cinerea associated with dicarboximide resistance wire studied. Spearman rank correlation coefficients were calculated betwee n resistance to iprodione and survival ability both outside and inside the greenhouse, measured on isolates randomly chosen from a collection done in a survey of commercial greenhouses in Southeastern Spain in 1992. Survival was measured at 47, 83, and 110 days as percentage of surviving mycelia in a sample of artificially inoculated tomato stem pieces and as percentage of viable sclerotia from a sample of sclerotia produced on potato dextrose ag ar. Resistance to iprodione was measured by the fungicide concentration tha t reduces fungal growth by 50% (EC50 values). Significant (P < 0.05) negati ve correlation coefficients between survival of sclerotia and resistance to iprodione were found for some samplings dates, which indicates that sclero tia of resistant isolates survive less well than sclerotia from sensitive i solates. For mycelia, no relationship between survival and resistance was f ound.