Evaluation of Heated Solutions of Sulfur Dioxide, Ethanol, and Hydrogen Peroxide to Control Postharvest Green Mold of Lemons. Joseph L. Smilanick, Research Plant Pathologist, Horticultural Crops Research Laboratory, Agricultural Research Service, U.S. Depart-; merit of Agriculture, 2021 South Peach Avenue, Fresno 93727 . Dennis A. Margosan, Research Technician, and Delmer J. Henson, Biological Aide, Horticultural Crops Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, 2021 South Peach Avenue, Fresno 93727. Plant Dis. 79:742-747. Accepted for publication 18 April 1995 . This article is indhe public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1995. DOI: 10.1094/PD-79-0742.

Lemon fruit were inoculated with spores of Penicillium digitatum and immersed in solutions of ethanol, sulfur dioxide, or hydrogen peroxide to control postharvest green mold. Green mold incidence and fruit injury were assessed after treatments employing various combinations of concentration, duration of treatment, temperature, and post-treatment rinses. Heating of the solutions was needed to attain acceptable efficacy. Sulfur dioxide and elhanol controlled green mold without injury to fruit, whereas hydrogen peroxide did not effectively control green mold and caused unacceptable injury to fruit. Treatments selected for extensive evaluation were im-mersion in 10% ethanol at 45°C for 150 s without rinsing, or in 2% sulfur dioxide at 45°C for 150 s followed by two fresh water rinses. These treatments were compared with two existing decay control methods: immersion in 3% sodium carbonate at 45°C for 150 s followed by two fresh water rinses, or in 1,000 µg/ml imazalil at 25°C for 60 s. Lemons were inoculated at 20°C then incubated for 12, 24, 48, or 60 h before treatments were applied. Efficacy of sulfur dioxide and ethanol treatments was comparable to that of sodium carbonate and imazalil. Sulfur diox-ide and ethanol did not injure the fruit and their residues were low. The sulfur dioxide content of lemons immediately after treatment was less than 1 μg/ml. The ethanol content of lemons analyzed immediately after ethanol treatment was 58.6 (±9.6) µg/ml and 24.4 (±11.7) μg/ml after storage for 7 days at 20 C. The ethanol content of untreated fruit was 3.3 μg/ml