Using rot risk assessment to make decisions (Rot risk assessment)

Once a rot risk has been identified for fruit from an orchard that is intended for medium – long-term storage, then decisions on treatment or time of marketing can be made.

• This information for Neonectria rot, Phytophthora rot and brown rot is summarised in below.
• For Gloeosporium and Botrytis (latent) rot, research did not identify any clear factors on which risk assessment could be based. Decisions on risk are therefore mainly based on rot history and rainfall.
• For Penicillium rot, Mucor rot and Botrytis (wound) rot, risk assessment is purely dependent on crop damage. Attention to crop handling and hygiene at harvest should avoid these problems.

Where decisions based on rot risk are made at harvest, options for control or minimising losses due to rots are based on reducing the storage time (earlier marketing).

Where orchard fungicide sprays are considered, decisions will need to be made much earlier, even at the start of the season. In these cases, decisions can be made based on rot history from packhouse records, or from orchard types identified as at risk, e.g. for Phytophthora – potential low hanging fruit, a high percentage bare ground or for Neonectria rot – a high incidence of cankered trees.