Effect of Preharvest Factors and Bruising in Stone Fruit Decay
The fruit skin (cuticle and epidermis) provides barrier protection against infection by pathogens. Most fungi are unable to penetrate healthy fruit skin and must enter through wounds. Fruit resistance to infection resulting from the biochemical action of tissues is not the result of a single compound or a single mechanism. Multiple systems with complex interactions may be involved in decay resistance.
Immature fruit appear to be resistant to pathogens due in part to fungitoxic compound(s) already present at the infection point. Even if immature fruit are penetrated by fungi, in many cases the fungus is unable to colonize the tissue. Commonly, a high degree of resistance is maintained until the fruit approaches maturity. This loss of resistance occurs at the same time that fruit firmness is decreasing. This means that softer, over-mature fruit not only are more susceptible to mechanical injury and infection but also lack the biochemical resistance of immature fruit. Cultural practices may condition fruit to different susceptibilities to disease, however there is little information on the relationship between preharvest factors and bruising on decay incidence. Also, postharvest handling will affect decay development. This article briefly describes the possible relationships between bruising, irrigation, nitrogen and calcium fertilization, and fruit decay incidence.