• Korean Journal of Environmental Agriculture
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• v.33 no.3
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• pp.198-204
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• 2014

BACKGROUND: Caused by cultural environment, the fruit skin stain results in serious damages to pear fruit. Particularly susceptible to this damage, 'Niitaka' pear accounts for 82% of pear cultivation in Korea and many farmers growing the pear trees have suffered economic losses due to fruit skin stain. This study investigated the effect of different treatments of 'Niitaka' pear during growing period on the occurrence of fruit skin stain. METHODS AND RESULTS: The treatments in the field included gibberellin (GA) paste, spraying with amino acid tree fertilizer, functional bagging, and coating of the inner paper bag with agents. The relationships between tree vigor, mineral nutrition concentration and fruit skin stain occurrence were also investigated. The fruit skin stain symptoms occurred from young fruit (May 25) until harvest. There was no exposed fruit flesh. The occurrence of fruit skin stain was significantly reduced in normal tree (shoot length 110 cm), as well as using GA paste treatment, and bagging in calcium and lime sulfur coated bags. However, spraying with amino acid tree fertilizer made no difference in comparison to control. In addition, bags in which the inner paper was coated with lime sulfur and soybean oil resulted in chemical injury to the fruit skin caused by bagging. The K concentration of shoot wood and fruit skin were higher than those of the control. Also, there were lower T-N, K concentration of leaf. CONCLUSION: These results suggest that occurrence of fruit skin stain in 'Niitaka' pear fruits during the growing period can be reduced by GA paste and bagging in calcium and lime sulfur coated bags. The symptoms of chemical injury to the fruit skin caused by bagging in lime sulfur and soybean oil coated inner paper were different compared to skin stain occurring in fruit during the growing period.

• Food Science and Preservation
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• v.10 no.4
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• pp.447-453
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• 2003

Causal factors related to the skin disorder such as black stains during cold storage of 'Niitaka' pear fruit are of great importance to solve the postharvest disorder problems. The morphological and biochemical changes observe of pear skin affected by different harvest times and storage environments. Occurrence rate of black stain in 'Niitaka' pear fruit was the highest in newspaper bagging with 75% among various bagging materials at harvest time because of the high relative humidity within the double layer paper bags. During cold storage, the rate was 54～100% in 30 $\mu\textrm{m}$ polyethylene (PE) film packaging. As the harvest time was postponed, the rate increasedduring cold stoinge. The into was 1.5 to 2.4 times higher in pears harvested in late September than in those harvested in early and mid October. There was no significant difference in occurrence of black stain fruit between the 30 and 50 $\mu\textrm{m}$ PE film bags. The causal fungus of the black stain pear was assumed as Gloeodes pomigena (Schweintz, 1920). The treatment of 0.1～0.5 ppm ozone gas prevented the occurrence of the pear fruit black stain until 180 days after cold storage. The ozone treatment on the affected fruit was also effective in preventing the progress of the black stain.

• The Plant Pathology Journal
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• v.30 no.3
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• pp.229-235
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• 2014

Pear skin stains on 'Niitaka' pears, which occur from the growing stage to the cold storage stage, reportedly negatively influence the marketing of pears. These stains on fruit skin are likely due to a pathogenic fungus that resides on the skin and is characterized by dark stains; however, the mycelium of this fungus does not penetrate into the sarcocarp and is only present on the cuticle layer of fruit skin. A pathogenic fungus was isolated from the skin lesions of infected fruits, and its pathogenicity was subsequently tested. According to the pathogenicity test, Mycosphaerella sp. was strongly pathogenic, while Penicillium spp. and Alternaria spp. showed modest pathogenicity. In this present study, we isolated the pathogenic fungus responsible for the symptoms of pears (i.e., dark brown-colored specks) and identified it as Mycosphaerella graminicola based on its morphological characteristics and the nucleotide sequence of the beta-tubulin gene. M. graminicola was pathogenic to the skin of 'Niitaka' pears, which are one of the most widely growing varieties of pears in South Korea.

• Food Science and Preservation
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• v.21 no.4
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• pp.468-472
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• 2014

The effect of pre-storage treatments was investigated to control the occurrence of fruit skin stain in 'Niitaka' pears. The incidence of fruit skin stains was significantly reduced when the fruits were stored in paper bags with a yellow inner color, compared to when they were stored in paper bags with blue and red inner colors. Additionally, the pear fruits that were harvested seven days earlier than their optimum maturity date developed less fruit skin stains in cold storage and retained their quality. Storage in polyethylene (PE) bags did not control the occurrence of fruit skin stains as effectively as did bag-free storage or storage in calcium-coated bags. The dipping of the pear fruits in a chlorine dioxide and calcium solution was highly effective in reducing the fruit skin stains compared to when they were not dipped or when they were dipped only in distilled water. In particular, a 1,500 times diluted solution of sodium dichloroisocyannurate (NaDCC) reduced the incidence of fruit skin stains and the size of the lesions. No stain was observed on the skin of the fruit with a water content lower than 67.7% (w/v) during its storage. In conclusion, packaging pear fruits in bags with an inner calcium coat and dipping them in a chlorine dioxide, calcium, or NaDCC solution can effectively reduce their skin stains during their storage.

• Research in Plant Disease
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• v.15 no.3
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• pp.230-235
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• 2009

Postharvest skin sooty dapple and decay disease of pear fruit often originates at small stain symptoms that occurred during harvest and handling. Experiments were conducted to characterize the effect of timing of application of disease control materials, and to evaluate sequential postharvest applications of fungicides or fungicides and bio-control agents. Fungicides and bio-control agents were increasingly less effective when the period between harvest and application was prolonged. Thiabendazole (TBZ) applied to fruit without artificial wounding or inoculation effectively reduced skin sooty and decay disease when applied within 3 weeks or 6 weeks in 2 years of study. TBZ, Fludioxonil and pyrimethanil were effective in controlling skin sooty and decay disease at artificial wounds inoculated with Cladosporium tenuissimum up to 14 days after inoculation. Application of TBZ at harvest followed 3 weeks later by application of Fludioxonil was superior to application of TBZ at harvest alone. Two bacterial biocontrol agents reduced skin sooty and decay disease at pear wounds inoculated with C. tenuissimum up to 14 days after inoculation with C. tenuissimum, but were ineffective when applied at 28 days after inoculation. Of possible sequential arrangements of fungicide and bio-control treatments, application of the most effective material promptly after harvest generally resulted in the highest level of disease control.