The incidence and severity of “`Braeburn' browning disorder” (BBD), a CO2-induced disorder of `Braeburn' apple (Malus ×domestica Borkh.), vary markedly with production district and orchard block. We investigated the effects of harvest date, blush, and crop load on fruit maturity, minerals, skin permeance, and BBD incidence. Incidence of BBD was higher in late-than in early-harvested fruit and in fruit on light than on heavily cropping trees, but blush intensity did not influence susceptibility to the disorder. Fruit maturity factors were affected by region, harvest date, blush type, and crop load, but no consistent relationships between these factors and BBD occurrence were found. Concentrations of Ca, Mg, and/or K were influenced by harvest date, blush type, and crop load, and skin permeance to gas exchange was affected by growing region and blush type, but not by harvest date or crop load. However, no physiological or mineral factor measured in this study was strongly correlated with susceptibility of fruit to BBD. Fruit from orchards that have a history of susceptibility to BBD, or subjected to adverse harvest date, regional, crop load, microclimate, and seasonal influences, should be segregated at harvest, and should not be held in controlled-atmosphere (CA) storage. Crop load should be managed to reduce the occurrence of biennial bearing.
