2019 ASHS Annual Conference

Harvista (preharvest 1-methycyclopropene; 1-MCP) was applied to replicate rows of ‘Honeycrisp’ apples, either 2 weeks (early), 1 week (late), at 1 and 2 weeks (repeated), or at double rate 1 week, before first commercial harvest. Fruit were then untreated or treated with postharvest 1-MCP and stored at 0.5^oC or 3^oC for 20 weeks. Fruit quality and physiological disorders were assessed after 4 days at 20^oC. Fruit from all Harvista treatments had lower internal ethylene concentrations (IECs) and were greener as indicated by higher I_AD values compared with untreated controls. The starch pattern indices were lower in the repeated and double treatments than in control and other Harvista treatments. After storage, Harvista-treated fruit were firmer, but effects of the different Harvista treatments were inconsistent. Effects of 1-MCP on IEC and I_AD values were greater at 0.5^oC than at 3^oC, but high incidences of soft scald, core browning and vascular browning, especially in Harvista-treated fruit at the lower temperature, confirmed that 3^oC is the correct temperature for this cultivar. After storage at 3^oC, Harvista-treated fruit had a higher incidence of bitter pit, but less skin wrinkling and senescent breakdown. 1-MCP treatment of Harvista fruit slightly decreased bitter pit incidence while greatly increasing that of core browning and leather blotch, and sometimes flesh browning and carbon dioxide injury. While Harvista may be a useful tool to delay harvest, effects on storage disorders must be taken into account, and caution used when 1-MCP applications are made to fruit after harvest.