Control of low‐level dicarboximide‐resistant strains of Botrytis cinerea by dicarboximide fungicides

The dicarboximide fungicide iprodione (‘Rovral’) gave a high degree of control of infection by low‐level dicarboximide‐resistant strains of Botrytis cinerea Pers.: Fr. on detached leaves of French bean ( Phaseolus vulgaris L .) when the inoculum was in the form of conidia, but not when a mycelial plug inoculum was used. This difference in response partially explains how low‐level dicarboximide‐resistant strains can be present in crops where dicarboximide fungicides are in use, without causing obvious losses of disease control.