• 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.

• 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.

• 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.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.10a
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• pp.75-75
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• 2018

Watermelons, Citrullus species(Cucurbitaceae), are native to Africa and have been cultivated since ancient times. T he fruit flesh of wild watermelon is watery, but typically hard-textured, pale-colored and bland or bitter. The familiar sweet dessert watermelons, C. lanatus, featuring non-bitter, tender, well colored flesh, have a narrow genetic base, suggesting that they are originated from a series of selection events in a single ancestral population. In this study, considered as sweet dissert watermelon, genetic resources, C. lanatus, comprising of traditional cultivars and local accessions were collected from 18 different countries in four continents. A total of 60 accessions were characterized morphologically according to RDA genebank descriptors combined with Japan and China, list for 11 qualitative characteristics, leaf length, leaf width, petiole length, petiole diameter-source, stalk end length, stalk diameter, fruit length, fruit diameter, rind thickness, flesh sugar content($^{\circ}brix$), fruit weight-sink, and 6 sink related characters, leaf margin incision-source, fruit shape, fruit skin ground color, fruit skin stain color, fruit skin stain pattern and flesh color-sink, were also investigated. Even though the relatedness between some morphological traits and fruit weight or fruit sweetness showed no significance, the accessions investigated have a great deal of variation for most of the morphological traits. Additionally, the accessions which showed good performance in flesh color and fruit shape (IT271048) and high sugar content of flesh (IT274119, IT290118) above 14brix, were investigated in this experiment. The accessions, which have the information on specific traits including the selected accessions could be introduced, distributed and investigated for further use.

• Korean Journal of Environmental Agriculture
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• v.33 no.3
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• pp.178-183
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• 2014

BACKGROUND: The white stain symptom of grape clusters and canes by dust-like particles occurred in many vineyards recently. This study was conducted to investigate the ecological characteristics of white stain symptom in grapevines and vineyards. METHODS AND RESULTS: Optimal climate condition for white stain symptom was $25^{\circ}C{\sim}30^{\circ}C$ with 60% of humidity. Moreover, closed condition with same humidity showed higher incidence rate of white stain symptom than ventilation condition. Grape varieties with black berry skin such as Campbell-Early and Kyoho were more sensitive to white stain symptom compare to varieties with green and red berry skin. Although the pathogens were not detected until March, they increased from April, and increased sharply from mid of July. The pathogens may overwinter in the infected stems and/or on the bark as a mycelium. According to the increase of sugar content of grape from August to September, the mycelium which was parasitic on the bark grew to move to the fruits through the stems, and finally reached the fruit stalk to detach berries from the clusters. CONCLUSION: Well ventilation is recommended inside the vineyard since mid-July with roll up an insect net. In addition, infected stems and fruits should be removed out from grapevines infected with pathogens in the vineyards.

• The Plant Pathology Journal
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• v.17 no.2
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• pp.110-113
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• 2001

Post-harvest diseases of kiwifruit caused severe damages on the fruits during storage, transportation, marketing and consumption. Phomopsis sp. was reported to be one of the major causal organisms of post-harvest fruit rots of kiwifruit. Symptoms of stem-end rot caused by Phomopsis sp. appeared at the stem-end area of the fruit as it ripened. The brown pubescent skin at the area became soft and lighter in color than the adjacent firm healthy tissues. A watery exudate and white mycelial mats were frequently visible at the stem-end area forming a water-drop stain down the sides on the dry brown healthy skin. When the skin was peeled back, the affected flesh tissue was usually watersoaked, disorganized, soft and lighter green than the healthy tissue. Phomopsis sp. was consistently isolated from the diseased fruits, and its pathogenicity was confirmed by an artificial inoculation test on healthy fruit of kiwifruits. The mycological characteristics of the telemorph state of the fungus produced on potato-dextrose agar were in accordance with those of Diaporthe actinidiae. This is the first report on the occurrence of a telemorph state of D. actinidiae as the causal organism of stem-end rot of kiwifruit in Korea.

• 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.