Storage spoilage in Swedish apple production and novel ways of predicting storability

Swedish apple industry faces many challenges when it comes to storage of apples. Pathogens such as Colleotrichum ssp., Neofabrea ssp., Botrytis cinerea and Penicillium expansum cause substantial losses during storage. Also physiological disorders like soft scald and senescent breakdown contribute to fruit losses. Many of these storage diseases and disorders are aggravated by either a too early or too late harvest time. To estimate optimal harvest time is however difficult and at the moment reliant on destructive maturity tests on a small number of arbitrarily chosen fruits. These tests may therefore not give the full picture of the ripeness across the orchard. To get a better prediction of optimal harvest time, a DA-meter was used in an investigation to compare this non-destructive method with traditional maturity indices. The method has been used in Europe and other parts of the world but optimal values for storage of Swedish apple cultivars are unknown. Storage trials were conducted for two Swedish apple cultivars with the aim of finding the optimal values for harvest. Storage diseases as well as storage disorders were monitored during the trials. For both ‘Aroma’ and ‘Discovery’ there was a higher incidence of storage rot in fruit with lower IAD. Longer storage time was also shown to increase the development of storage rot.