Introduction. Apples are potentially subject to blue mold decay caused by Penicillium expansum ifstored at 1 °C for three or more months or if wounded during handling. Results from trials with applescontaminated with conidia of P. expansum and fumigated in small chambers with acetic acid (AA) vapor indicatedthat fruit could be sterilized to reduce decay without effect on fruit quality. The objective of this study was todetermine if larger quantities of apples treated with AA vapor would have less decay after storage and/or wounding. Itwas also important to determine if fumigation would affect apple quality and aroma. Materials and methods. Applecultivars were harvested at commercial maturity for use in AA fumigation trials. Apples artificially or naturallycontaminated with conidia of P. expansum were fumigated with AA vapor in a 1 m3 gas tight chamber at10 °C for 1 h to 24 h or dipped in 450 μg thiabendazole × L-1 solution. Fruit fumigatedin standard wooden or plastic apple boxes, or small wooden bins were either wounded and evaluated for decay after a weekat 20 °C or stored at 1 °C for three or more months and evaluated for decay. Then apple quality wasassessed. Results. Apples naturally contaminated with Penicillium spp. that had been stored at1 °C in air storage and treated with AA vapour had 50% less decay than the control fruit. In anotherexperiment, AA fumigation was as effective as thiabendazole in reducing decay. AA fumigation reduced decay of fruitcoming out of storage for apples stored for 3 months, and a second AA fumigation reduced infection of wounds on thesesame apples. AA fumigation before storage did not affect apple quality or vinegar aroma. Discussion. AA fumigationshowed great potential for reducing decay in stored apples. It could be used as an organic alternative to syntheticfungicides for control of blue mold decay.