The susceptibility of strawberry flowers in various stages of development to attack by Botrytis cinerea Pers. ex Fr. was assessed in an attempt to improve the timing and thereby the effectiveness of spray programmes. In the six cultivars used, the open-flower and white-bud stages were the most, and the green-bud stage was the least, susceptible to infection that resulted in blossom blight, the calyx and corolla being more readily infected than the receptacle. The cultivar ‘Royal Sovereign’ had both the most susceptible flowers and those susceptible for the longest period, whilst ‘Redgauntlet’ had the most resistant flowers. The open-flower stage was the most, and the green-bud stage the least, susceptible to the establishment of latent infection leading to eventual fruit rot. Inter-cultivar differences in susceptibility to fruit rot paralleled those involved in blossom blight, and the incidence of flower lesions was well correlated with the incidence of fruit rot in the field. The susceptibility of flowers to infection resulting in fruit rot was not closely related to fruit susceptibility as measured by the rate of growth of the fungus in ripe or unripe receptacle tissue. The incidence of calyx and total flower lesions, however, was related to fruit susceptibility determined in this way provided that a spore inoculum was used on ripe receptacles to initiate the growth.