Overview of postharvest disease management practices on apple: prevention, monitoring and control

Postharvest apple diseases are primarily caused by fungal pathogens, as Penicillium spp. and Botrytis spp. that enter through wounds. Increasingly relevant latent pathogens, such as Neofabraea alba and N. kienholzii (bull’s eye rot), Ramularia mali (dry lenticel rot), Colletotrichum spp. (bitter rot), and Alternaria spp. (black rot), develop in postharvest. White haze, which affects fruit quality, is linked to basidiomycetous genera such as Entyloma, Golubevia, and Tilletiopsis, with new species like E. mali and G. mali identified. Molecular diagnostic tools are used for pathogen detection and monitoring. Fruit microbiome analysis indicates that white haze agents are epiphytic and appear just before harvest, while R. mali is endophytic three months before harvest and becomes epiphytic during storage. R. mali and N. alba are found in orchard environments early in the season. Postharvest disease management strategies include the use of two Aureobasidium pullulans strains against white haze, which showed efficacy comparable to chemical treatments at the end of shelf-life. These strains proliferate well on treated fruit both epiphytically and endophytically. Biofumigation with thyme, savoury, and basil essential oils (EOs) at varying concentrations was tested against Botrytis cinerea, showing that thyme and savoury EOs are effective in preventing grey mould rot. Essential oils not only inhibit pathogen growth but also induce resistance in the fruit. Slow-release EO diffusers of basil, oregano, savoury, thyme, lemon, and fennel were tested against blue mould caused by Penicillium expansum, with lemon and oregano EOs showing the highest efficacy after 60 days of storage and an additional 14 days of shelflife.