Inking in Spanish peaches: possible causes and solutions

Inking has become a frequent skin disorder in red-blushed peach fruit over the last decade in different production areas in the Ebro Valley, the main peach production area in Spain. It is characterized by discolored brown-and-black spots on the skin. Although inking only affects the fruit's cosmetic appearance, it causes economic losses to the peach industry because blemished fruits are not marketable. According to the literature, abrasion is one of the main precursors of inking. It causes the release of phenolic pigments (anthocyanin, chlorogenic acid, etc.) located in skin cells and allows the reaction of these pigments with metal contaminants (iron, aluminum, etc.). We hypothesize that cultivar type, different orchard and harvest management practices, climatic conditions, fruit quality, and maturity stage could also be important factors that influence inking on peaches and therefore their susceptibility to inking (and its incidence and severity). These factors were evaluated over three seasons (2019-2021). Differences in the severity and incidence of inking were observed among cultivars between the different seasons, where some cultivars exhibited the same trends over the three-year period. Orchard management also influenced the incidence of inking for a given cultivar. Other factors, such as irrigation regime, harvesting method, harvest time, and maturity stage, also had an influence on inking development. Further experimental data are needed to better understand how these factors work and interact. Such knowledge will help to reduce this skin disorder, however at this stage there is no known way to prevent it.

Automated summary

Inking has become a common skin disorder on peach fruit, caused primarily by abrasions, with factors such as orchard management, fruit quality, and maturity stage potentially influencing susceptibility and incidence of inking.