Effects of Host Physiology on the Development of Core Rot, Caused byAlternaria alternata, in Red Delicious Apples

Abstract

Alternaria alternata is the predominant fungus involved in moldy core and core rot of Red Delicious apples. The effects of environmental conditions during bloom on moldy core and core rot, and on the need for fungicide application, were examined in 10 experiments carried out in 2007. In untreated experimental plots, typical moldy core symptoms were very common, with relatively low variability (coefficient of variation: 22.2%) among experiments; core rot incidence ranged from 2 to 26% with large variability (coefficient of variation: 90.0%) among experiments. No evidence of prevailing environmental conditions during bloom affecting the development of moldy core or core rot was detected. No effect of fungicide application (a mixture of bromuconazole + captan three times a week at bloom) on moldy core or core rot was found. A random distribution of moldy core and an occasional aggregation of core rot in the orchards were indicated from Morisita's index of dispersion (I(δ)). The hypothesis that core rot incidence is governed by host physiology and that yield load can be used as an indicator of trees' susceptibility was examined in a set of eight observations and four experiments. No correlation was found between tree yield load and moldy core, but core rot incidence was inversely related to yield load. Furthermore, irrespective of tree yield load, core rot was more abundant on large compared with small fruits. It is concluded that host physiology, rather than pathogen occurrence or environmental conditions at bloom stage, governs the development of core rot in Red Delicious apples caused by A. alternata in Israel.

Epidemiology of Mouldy Core and Core Rot of Apple in Himachal Pradesh, India

“…These findings are in accordance with those of Shtienberg (2012) who reported that core rot was more abundant on large fruits as compared to small size fruits in Israel. Ellis and Barrat (1983) reported that the fungus Alternaria sp.…”

Alternaria alternata (Black Rot, Black Spot)

“…The most common path for fruit infection used by A. alternaria is through wounds produced by mechanical damage, sunburn or chilling injury, before, during or after harvest, as observed on tomatoes (Grogan et al, 1975;Pearson and Hall, 1975), blueberries (Ceponis and Capellini, 1978), apples (Shtienberg, 2012), persimmon , and mango (Prusky, 1996). In addition, Alternaria infection via natural openings has been observed in table grapes, mandarin, and tangelo, among others.…”

“…Warmer temperatures favor the development of the rot, therefore keeping apples at temperatures of 0 to 4.4°C when moving them from storage to the consumer helps to prevent spoilage (Chen et al, 2012;Shtienberg, 2012). The lesions following these physiological disorders are usually not sunken and often are without definite margins.…”

“…As mentioned above, besides A. alternata's presence in many regions of the world, this fungus has been found to be responsible for different diseases during the postharvest shelf-life of many different horticultural products including stem-end rot of mangoes (Amin et al, 2011), black rot in cherry tomatoes , core browning and moldy core of fuji apples , fruit spot on apples (Harteveld et al, 2013), moldy core and core rot in apples (Shtienberg, 2012), black rot of mandarins (Nemsa et al, 2012), black rot of kiwi fruit (Kwon et al, 2011), fruit rot in immature cucumbers (Al-Sadi et al, 2011), black spot in melons , moldy heart on peaches (Pose et al, 2010), brown spot disease on tangerines as well as in its related hybrids (Reis et al, 2006), fruit rot of Capsicum annuum (Anand et al, 2009), brown spot of mandarins (Fourie et al, 2009), Alternaria rot on figs (Doster and Michaillides, 2007), pericarp browning on litchi fruits (Sivakumar et al, 2007), Alternaria rot of pingguoli pear (Pyrus bretschneideri Rehd. As mentioned above, besides A. alternata's presence in many regions of the world, this fungus has been found to be responsible for different diseases during the postharvest shelf-life of many different horticultural products including stem-end rot of mangoes (Amin et al, 2011), black rot in cherry tomatoes , core browning and moldy core of fuji apples , fruit spot on apples (Harteveld et al, 2013), moldy core and core rot in apples (Shtienberg, 2012), black rot of mandarins (Nemsa et al, 2012), black rot of kiwi fruit (Kwon et al, 2011), fruit rot in immature cucumbers (Al-Sadi et al, 2011), black spot in melons , moldy heart on peaches (Pose et al, 2010), brown spot disease on tangerines as well as in its related hybrids (Reis et al, 2006), fruit rot of Capsicum annuum (Anand et al, 2009), brown spot of mandarins (Fourie et al, 2009), Alternaria rot on figs (Doster and Michaillides, 2007), pericarp browning on litchi fruits (Sivakumar et al, 2007), Alternaria rot of pingguoli pear (Pyrus bretschneideri Rehd.…”

A Single-Nucleotide Polymorphism in the Promoter of a Hairpin RNA Contributes to Alternaria alternata Leaf Spot Resistance in Apple (Malus × domestica)

“…In general, when fungi attack apple leaves, they produce toxins and effectors, which disrupt plant metabolism (Hugot et al, 1999;Johnson et al, 2000;Abe et al, 2010), leading to H 2 O 2 accumulation and cell death (Chung, 2012). In addition, fungal diseases result in black, necrotic leaf spots and moldy fruit cores (Otani et al, 1974;Johnson et al, 2000), an increased incidence of defoliation and fruit drop, and a decline in fruit quality and production (Sawamura and Yanase, 1963;Rotem, 1994;Rotondo et al, 2012;Shtienberg, 2012). Chemical treatments are commonly used to control fungal diseases, but such treatments have negative side effects, such as reduced food safety and environmental pollution.…”