Fungal rots are responsible for significant losses in stored apple in most seasons. They can be divided into two broad groups:
- Those causing rots primarily after harvest (store diseases)
- Those that also cause rots in the orchard (orchard diseases)
Rotting in store due to the latter group mainly results from fruit infection that occurred before harvest, but remained symptomless and subsequently developed in store. The store diseases are usually wound rots which gain entry to damaged fruit at harvest.
Cox is most susceptible to rotting. Losses in other varieties such as Bramley, Braeburn, Gala or Jonagold are usually much lower, but occasionally certain fungi e.g. Phytophthora syringae, can cause significant losses in these varieties. Orchards differ considerably in actual losses due to rots and the main fungi responsible.
Information on losses in store and the rots responsible for an orchard is important if losses are to be minimised and the appropriate control measures applied. This information can be obtained from assessment of rots in the packhouse during grading.