Control of Brown Rot Decay of Nectarines with 15% Carbon Dioxide Atmospheres

Abstract

Effects of short-term exposure to a 15% CO2 atmosphere on nectarines [Prunus persica (L.) Batsch (Nectarine Group) `Summer Red'] inoculated with Monilinia fructicola (Wint.) Honey (causal agent of brown rot) were investigated. Nectarines were inoculated with spores of M. fructicola and incubated at 20 °C for 24, 48 or 72 hours and then transferred to storage in either air or air enriched with 15% CO2 at 5 °C. Fruit were removed from storage after 5 and 16 days and were examined for brown rot decay immediately and after ripening in air for 3 days at 20 °C. Noninoculated nectarines were stored and treated likewise for evaluation of postharvest fruit attributes to determine their tolerance to 15% CO2. Incubation period after inoculation, storage duration, and storage atmosphere had highly significant effects on fruit decay. `Summer Red' nectarines tolerated a 15% CO2 atmosphere for 16 days at 5 °C. Development of brown rot decay in fruit inoculated 24 hours before 5 or 16 days storage in 15% CO2 at 5 °C was arrested. After 3 days ripening in air at 20 °C, the progression of brown rot disease was rapid in all inoculated nectarines, demonstrating the fungistatic effect of 15% CO2. The quantity of fungal cell wall materials (estimated by glucosamine concentration) was compared to visual estimation of decayed area and visual rating of fungal sporulation. The glucosamine assay defined the onset and progress of brown rot infection more precisely than either of the two visual tests.