Effects of Acidity of Simulated Rain on the Fruiting of ‘Summerred’ Apple Trees

The effects of rain acidity on field‐grown ‘Summerred’ apple trees ( Malus domestica Borkh) under natural conditions were investigated. One group of four trees was exposed to ambient rainfall. Four other groups were covered with rainshields and received water, pH 5.6, 4, and 3, respectively, as simulated rain. Simulated acid rain, particularly at pH 3, adversely affected fruit production in terms of individual fruit weight, fruit set, fruit appearance (necrosis and russetting of the peel) and dry weight. Ambient rain was not found to cause significant reductions in apple fruit production in this study.