PHYTOTOXIC RESPONSE OF DANCY TANGERINE TO HIGH-TEMPERATURE, MOIST, FORCED-AIR TREATMENT FOR FRUIT-FLY DISINFESTATION

Early season degreened 'Dancy' tangerines (Citrus reticulata Blanco) w ere size graded and subjected to high-temperature, moist, forced-air ( HTMFA) treatments using air at 45, 46, or 48C for 0, 1, 2, 3, or 4 hou rs. The phytotoxic response of fruit to the heat treatments was evalua ted immediately after treatment and weekly during 3 weeks of cold (4C) storage. Mortality of nonfeeding, third instar Mexican fruit fly [(An astrepha ludens (Loew)] larvae was estimated for each time-temperature heat treatment combination in water baths that simulated the heating and cooling profiles of heat-treated fruit. Unacceptable phytotoxic sy mptoms, such as inferior flavor and darkened flavedo tissue, were obse rved when fruit was treated at 46 or 48C. Fruit heated with 45C forced moist air had flavedo color change (DELTAL), percent juice yield, so luble solids concentration, and flavor ratings that were statistically similar to ratings for unheated, control fruit. An HTMFA treatment of 3 or 4 hours at 45,46, or 48C and subsequent cooling was sufficient t o kill 100% of naked larvae in water baths. Market quality of fruit wa s maintained after a 4-hour HTMFA treatment at 45C, and 100% mortality of naked larvae occurred after 3 hours at 45C.