Hormetic effects of carbendazim on the virulence of Botrytis cinerea

The ascomycete plant pathogenic fungus Botrytis cinerea infects more than 1400 host plant species worldwide. Stimulatory effects of sublethal doses of fungicides on plant pathogens are of close relevance to disease management. In the present study, stimulatory effects of carbendazim on the virulence of B. cinerea to cucumber plants were investigated. Spraying carbendazim on cucumber plants at 3 to 200 μg/ml had stimulatory effects on the virulence of carbendazim-resistant isolates of B. cinerea and the maximum percent stimulations were 16.7% and 13.5% for isolates HBtom451 and HBstr491, respectively. Preconditioned mycelia, i.e., mycelia grown on potato dextrose agar (PDA) amended with carbendazim at concentrations of 10, 50 or 200 μg/ml, also showed increased virulence. The maximum percent stimulations for isolates HBtom451 and HBstr491 were 7.9% and 9.5%, respectively. Compared with mycelia grown on PDA without carbendazim, virulence stimulation magnitudes of spraying carbendazim on leaves increased mod...