Effects of Preharvest and Postharvest 1-Methylcyclopropene Treatment on External CO2 Injury in Apples during Storage

The objective of this study was to investigate the effects of preharvest and postharvest 1-methylcyclopropene (1-MCP) treatment on the incidence of external CO2 injury in apples during storage. During a period of 4 years, 'McIntosh' or 'Empire' trees were either untreated or sprayed 7 to 11 days before harvest with 1-MCP (Harvista (TM)). Following harvest, apples were cooled overnight and then treated within 7 days with or without 1-MCP (SmartFresh(SM)) for 24 hours at 3 degrees C. Apples were subsequently held in controlled atmosphere (CA) at 3 degrees C for 6 or 9-91/2 months. Apples from trees sprayed with Harvista and/or treated with SmartFresh developed more external CO2 injury, compared to those not treated. The incidence was greatest in SmartFresh-treated fruit that had been sprayed with Harvista containing the highest 1-MCP concentration, while less CO2 injury developed when SmartFresh was applied closer to harvest. The usual 1-MCP effect of improved firmness retention was observed throughout.