Rot Risk Assessment - General

Research has shown that Cox orchards vary considerably in the actual losses due to rots in store and the main fungi responsible for the losses. Therefore, actual rotting in store is very much related to orchard site.

The purpose of rot risk assessment is to:

1. identify those orchards with fruit likely to have significant rotting in store, so that appropriate measures can be taken to minimise losses and
2. avoid unnecessary treatment on orchards where the risk of rotting in store is minimal.

Rot risk assessment is based on assessment of various factors pre-harvest from which a decision can be made on the likely rotting in store and therefore the need for treatment.

The system has been developed for Cox because, in general, losses due to rots in store for other varieties such as Bramley, Gala and Jonagold are usually minimal. The system, however, is probably applicable to all varieties.

The factors assessed pre-harvest are as follows:

• daily rainfall
• orchard factors
• fungal inoculum (brown rot and canker)
• crop load
• % bareground
• % crop <½ metre from ground
• orchard rot history
• fruit storage potential (mineral composition and firmness)

Rainfall measurement

Orchard factors

Orchard rot history

Fruit storage potential

Using rot risk assessment to make decisions

Procedures for assessment of orchard factors affecting rotting in store

Orchard rot history - examples of packhouse records

Fungicide sprays for control of storage rot efficacy & safety factors

Apple store diseases - wound pathogens - Rot management options

Apple orchard disease - Rot management options