Radio frequency-hot water dips for postharvest codling moth control in apples

A combination radio frequency-hot water dip method was examined as a potential quarantine treatment against fifth instars of the codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), in apples, Malus sylvestris (L.) var. domestica (Borkh.) Mansf., which were intended for export to Japan. The apples were initially exposed to 27.12-MHz radio frequency energy at 12 kW for 2.75 min and were then submerged in a range of hot water dips (48-50C) for different durations. Efficacious tests were at 48C for > 2 h, at 49C for > 50 min and at 50C for > 40 min. Fruit quality tests indicated that the best hot water parameters were at 50C for 40 min. Fruit quality after 2 weeks was cultivar dependent where Fuji apples tolerated heat treatment better than Delicious and Gala apples. None of the treated fruits were acceptable after 60 days. Regardless of cultivar, heat treatment resulted in loss of both peel and fresh colors, coupled with reduced firmness and increased external and internal damage.