The use of vinegar vapor to reduce postharvest decay of harvested fruit

Vapors of several common vinegars containing 4.2% to 6.0% (= 2.5 to 3.6 mol .L-1) acetic acid effectively prevented conidia of brown rot [Monilinia fru cticola (G. Wint.) Honey], gray mold (Botrytis cinerea Pers.:Fr.), and blue mold (Penicillium expansum Link) from germinating and causing decay of sto ne fruit (Prunus sp.), strawberries (Fragaria xananassa Duchesne), and appl es (Malus xdomestica Borkh.), respectively. Fruit were fumigated in 12.7-L sealed containers in which vinegar was dripped on to filter paper wicks or vaporized by heating from an aluminum receptacle, Vapor from 1.0 mL of red wine vinegar (6.0% acetic acid) reduced decay by M. fructicola on 'Sundrop' apricots (Prunus armeniaca L.) from 100% to 0%. Similarly, vapor from 1.0 mt of white vinegar (5.0% acetic acid) reduced decay in strawberries by B. cinerea from 50% to 1.4%. Eight different vinegars, ranging from 4.2% to 6. 0% acetic acid, of which 0.5 mL of each vinegar was heat-vaporized, reduced decay by P. expansum to 1% or less in 'Jonagold' apples, The volume of hea t-vaporized white vinegar (5.0% acetic acid) necessary to reduce decay by P . expansum on 'Jonagold' apples to zero was 36.6 mu L.L-1 of air. Increasin g the number of conidia on the apple surface reduced the effectiveness of v inegar vapor. The number of lesions caused by P. expansum on 'McIntosh' app le decreased exponentially with increasing time of fumigation, approaching zero after about 6 hours. These results suggest that vinegar vapor could be an effective alternative to liquid biocides such as sodium hypochlorite fo r sterilization of surfaces contaminated by conidia of fungal pathogens.