In Israel, black spot, caused by Alternaria alternata, is the main postharvest factor that reduces quality and impairs storability of persimmon fruits Diospyros kaki cv. Triumph. The fungus infects the fruit in the orchard and remains quiescent until harvest or renews its development just before harvest, following rain or high humidity, and then preferentially colonizes the stem side of the fruit. Recent findings suggest the importance of ethylene and respiration, early during fruit growth, as factors influencing maturity, crack development, and susceptibility to Alternaria black spot (ABS) colonization in the stem end side of the fruit. We tested the effects of the growth regulator Superlon – a mixture of gibberellin (GA₄₊₇) and benzyl adenine (BA) – on fruit physiological responses during growth on ABS incidence. Superlon treatments during early stages of fruit growth, i.e. starting 40 days after fruit set (dafs), inhibited ethylene and CO₂ evolution of the stemd end side. Application of the treatment at later state of fruit development, i.e. 100 dafs, enhanced cell proliferation of the external layers of the exocarp under the fruit cuticle. In both cases, Superlon delayed chlorophyll degradation, and reduced fruit cuticle cracks and ABS susceptibility during late stages of fruit growth and during storage. These results suggest that the phytohormone, acting as a modulator of host physiological responses that resulted in delayed fruit maturation, is a main factor in enhanced resistance to ABS at harvest and during storage.