EFFICACY OF A NEW SO2 GENERATOR PAD IN MAINTAINING POSTHARVEST QUALITY OF TABLE GRAPES

Gray mold is the most damaging postharvest disease of table grapes, due to the ability of the causal agent, Botrytis cinerea Pers., to adapt to different environmental conditions. A success factor in long-term storage of table grapes is the application of SO2 generator pads. Our research aimed at testing the activity of a new SO2 generator pad (Decco, Italia) on gray mold and quality of table grapes cv. Italia and Red Globe stored for 90 days. The test involved the application of the pad in three different moments: in the field, prior to precooling, and immediately after precooling. In addition, three different bags were used for packaging: perforated and unperforated plastic liners and the new Decco MAP (modified atmosphere packaging) bag. At 30 days of storage, ‘Red Globe’ packed in the field or just before precooling with SO2 generator, showed no infection by B. cinerea; while 23-33% of clusters were infected when the pad was inserted after precooling, with no significant differences among the various plastic liners used. Clusters cv. Italia showed a similar trend but a lower disease incidence as compared to ‘Red Globe’, with a maximum of 10% of infection in presence of SO2. The highest incidence of rots was recorded at 90 days on cv. Red Globe with increasing values moving from perforated to unperforated plastic liners and the new Decco MAP bag. In absence of SO2 generators, the infections on both cultivars reached 100%. Clusters of ‘Italia’ and ‘Red Globe’ packed with Decco MAP showed the best quality.