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The main objective of this study was to investigate the effectiveness of preharvest 1-methylcyclopropene (1-MCP) treatment on the development of soft scald in ‘Honeycrisp’ apples. In addition, the effects of preharvest 1-MCP on fruit quality at harvest and after storage were examined. For two consecutive years of study, ‘Honeycrisp’ trees were sprayed preharvest with 1-MCP and fruit were harvested twice during each year. Preharvest 1-MCP treatments had little consistent effect on fruit maturity at the time of harvest. In both years of study, preharvest 1-MCP reduced the incidence of soft scald in ‘Honeycrisp’ apples after air storage at 0 or 3 °C for 5 or 6 months. Soggy breakdown developed only in the second year of study and high incidences were reduced by preharvest 1-MCP treatments. Preharvest 1-MCP often reduced flesh firmness loss in ‘Honeycrisp’ during storage, especially during the second year of study, and with 1-MCP application closer to harvest. Malic acid content was often higher in apples with the preharvest 1-MCP spray closer to harvest. Overall, the most important benefit of preharvest 1-MCP treatments on ‘Honeycrisp’ apples was the reduction in soft scald development. Due to the high potential for substantial fruit losses from this disorder, the use of preharvest 1-MCP sprays on ‘Honeycrisp’ apples could be very advantageous.

The objective of this study was to investigate the effects of rapid consecutive 1-methylcyclopropene (1-MCP) treatments on apple quality and disorders in storage. ‘McIntosh’ and ‘Spartan’ apples were harvested twice from commercial orchards and 1-MCP (1 μL·L⁻¹) was applied postharvest either 1 day after harvest or 1 and 2 days after harvest. Similar fruit from both cultivars were also not treated with 1-MCP, plus an additional treatment of 2 μL·L⁻¹ (double rate) 1-MCP was used on ‘McIntosh’. Fruit were held in either air storage at 0.5 °C for three or six months or in controlled-atmosphere (CA) storage for six or nine months. Overall, 1-MCP treatment improved firmness and acidity retention and reduced internal ethylene in both cultivars. However, ‘Spartan’ stored in CA often maintained these attributes without 1-MCP. ‘McIntosh’ apples treated twice with 1-MCP were often firmer than those treated just once. All 1-MCP treatments substantially reduced superficial scald and there was no difference in scald incidence among the treatments. Core browning was generally reduced by 1-MCP, but fruit treated once with 2 μL·L⁻¹ or twice with 1 μL·L⁻¹ 1-MCP sometimes had higher incidence than fruit treated only once with 1 μL·L⁻¹. ‘Spartan’ treated twice with 1-MCP also had higher incidence of internal browning after nine months. 1-MCP increased the incidence of external CO₂ injury in ‘McIntosh’ from the first harvest, with fruit treated with 2 μL·L⁻¹ having the highest incidence after six months of CA storage and those treated once with 1 μL·L⁻¹ having the highest incidence after nine months. Storage rots were greatest after six months of air storage and 1-MCP treatments usually reduced the incidence, regardless of treatment. These results suggest that using more than the traditional single application of 1 μL·L⁻¹ 1-MCP may improve firmness retention, but there is also some risk associated with increased disorders, especially when storing apples long-term, such as for six months in air or nine months in CA storage.