Effects of preharvest application with calcium and maturity at harvest in European plum postharvest

The combination of preharvest treatments with calcium chloride and fungicides, and storage of maturity graded fruit were assessed in five European plum cultivars. At harvest, samples of fruit within a commercially suitable range in ripening were divided into two categories: less-ripe (tree ripe-) and more-ripe (tree ripe+). The fruit were stored for 10?14 days at 4 ?C followed by 2?3 days at 20 ?C before the assessment of fungal decay. If calcium chloride was applied six times each season, postharvest fruit decay was significantly reduced in four of nine experiments, with a total mean reduction of around 50%. Two calcium applications in combination with a fungicide treatment reduced decay by approx. 60% compared to the untreated in one experiment. In six of seven experiments there was no effect of preharvest fungicide applications. In six of 10 experiments, fruit of the category tree ripe- had fewer fruit with fungal decay after storage than the tree ripe+fruit. The higher incidence in the category tree ripe+fruit was primarily due to brown rot, Mucor rot, and blue mould. For the category tree ripe+, there was two to ten times more decay than on tree ripe- fruit after a simulated shelf-life period. To ensure low incidence of fungal decay, fruit of commercial harvest maturity may thus be separated in two ripening categories, one for rapid distribution to the market (tree ripe+) and another for extended distribution time (tree ripe-). The text before is the Abstract of the paper IntroductionIn Norway, domestically produced cultivars of European plum (Prunus domestica L.) are marketed for fresh consumption within 2?3 weeks after harvest. Fungal fruit decay and softening (over-ripening) are important factors limiting the length of time plums are available for marketing (Vangdal et al., 2007a). To ensure a long sales period of high-quality fruit, preharvest applications with synthetic fungicides are commonly done. Fruit is harvested at the recommended optimal time, and the criteria for timing of harvest are based on observations of color and firmness (Vangdal & Flatland, 2010). Fungal fruit decay observed on plum after storage in Norway include brown rot (Monilinia spp.), grey mould (Botrytis sp.), blue mould (Penicillium sp.), Mucor rot (Mucor piriformis) and anthracnose (Colletotrichum acutatum) (B?rve & Vangdal, 2007). Applications of calcium have been proposed as a means to reduce postharvest fungal decay and improve fruit quality in plum (Vangdal & B?rve, 2002; Wojcik, 2001) and peach (Conway et al., 1987; Elmer et al., 2007; Hemat et al., 2014). Calcium may both enhance resistance against decay and have a direct fungicidal effect. The latter was documented in vitro for Botrytis cinerea (Wiesniewski et al., 1995), Penicillium expansum (Sto?i? et al., 2014; Wiesniewski et al., 1995), Colletotrichum acutatum (Biggs, 1999; Sto?i? et al., 2014), Monilinia fructicola (Biggs et al., 1997), and Rhizopus stolonifer (Tian et al., 2002). It has been proposed that the increase in disease resistance following calcium applications may be due to changes in cell degrading enzymes and firmness (Conway et al., 1994; Hocking et al., 2016). European plum cultivars produced in Norway and used for fresh consumption are picked within a certain range in maturity when delivered to packinghouses for grading and packing. Following grading, over-ripe fruit are discarded, while under-ripe fruit are stored for further ripening before marketed. Fruit ripening leads to senescence and cell deterioration, providing tissues well suited for infection of fungal pathogens (Alkam & Fortes, 2015). More mature fruit may therefore develop fungal decay faster than less mature fruit, as documented for brown rot on peach (Gradziel, 1994). Introduction of non-destructive assessment of fruit ripening has provided a possibility to follow maturation on the trees, as e.g., in peach (Ziosi et al., 2008), and to sort fruit according to ripening status at harvest (Spadoni et al., 2016). The effect of smaller differences in maturity on fungal decay among fruit harvested at the same time is less studied; however, in peach a close relationship was found between fruit ripening and brown rot (Spadoni et al., 2016). The objective of the present investigation was to show how preharvest applications of calcium in combination with maturity grading at harvest may affect postharvest fungal fruit decay in European plum. Sources and full texetPreharvest application with calcium and maturity at harvest affects postharvest fungal fruit decay of European plumJorunn B?rve, Eivind Vangdal & Arne Stensvand European Journal of Plant Pathology (2023)https://doi.org/10.1007/s10658-023-02654-7 Picture, Huelva Informaci?n, https://www.huelvainformacion.es/vivir_en_huelva/Ciruela-Prunus-domestica_0_1221778474.html