Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 2005
Publication Date: June 1, 2005
Citation: Smilanick, J.L. 2005. Eliminating or minimizing the use of fungicides to control postharvest diseases of fresh fruit. Phytopathology. 95:S140. Technical Abstract: Several approaches were combined into practical commercial strategies to eliminate or minimize postharvest fungicide use on citrus fruit. The fungicides thiabendazole (TBZ) and imazalil (IMZ), typically used at 2000 to 4000 µg/ml in citrus waxes, are applied primarily to control green mold, caused by Penicillium digitatum. The most effective approach to minimize fungicide use was to combine the existing approved fungicides with sodium bicarbonate (NaHCO3). The effectiveness of TBZ was maximized by employing an aqueous rather than wax TBZ solution, mild heating (41 degrees C) of the solution, adding NaHCO3, and completely immersing fruit, rather than drenching them, in the solution. These measures improved TBZ activity; even an isolate with TBZ-resistance was significantly controlled. In semi-commercial tests with naturally inoculated navel oranges from five groves, treatment with a solution containing only 350 µg/ml TBZ and 3% wt/vol NaHCO3 reduced green mold incidence from 11% among untreated oranges to 2%. Similar approaches improved IMZ performance; even IMZ resistant isolates could be partially controlled. Green mold among lemons inoculated IMZ-resistant isolate D201, and treated 24 h later with water, 500 µg/ml aqueous IMZ, 3% NaHCO3, or their combination, was 96.3, 63.0, 44.4, and 6.5%, respectively. NaHCO3 did not influence IMZ fruit residue levels.