• Research in Plant Disease
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• v.19 no.1
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• pp.1-6
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• 2013

Optimal spray time, interval and number of preventive fungicides against fruit rots of kiwifruit were investigated at the orchard which both green kiwifruit cultivar 'Hayward' and gold kiwifruit cultivar 'Hort16A' are cultivating side by side during 2009 and 2010 growing seasons in Jeju island, Korea. The highest control efficiency was obtained from benomyl WP and followed by thiophanate-methyl WP and carbendazim+diethofencarb WP. The control efficacies of the fungicides were much higher when applied onto the kiwifruit canopy after the flowering time than before the flowering time but thereafter their control efficiencies were decreased drastically according to delays of spray timing. With increasing spray numbers of the fungicides, the control efficacy increased. However, optimal spray time, interval and number of the preventive fungicides for the effective control of fruit rots of kiwifruit were determined as 4 time-spray schedule with 2-week-interval just after the flowering time on both 'Hayward' and 'Hort16A' cultivars.

• Plant Biotechnology Reports
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• v.4 no.1
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• pp.15-21
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• 2010

The over-expression of Arabidopsis CAX1 and CAX2 causes transgenic tomato plants to reveal severe $Ca^{2+}$ deficiency-like symptoms such as tip-burn and/or blossom end rot, despite there being sufficient $Ca^{2+}$ in each plant part. To correct the symptoms and to moderately enhance the calcium level, a worldwide vegetable tomato was genetically engineered using a modified Arabidopsis cation/$H^+$ antiporter sCAX2A, a mutant form of Arabidopsis CAX2. Compared with the wild-type, the sCAX2A-expressing tomato plants demonstrated elevated $Ca^{2+}$ levels in the fruits with almost no changes in the levels of $Mn^{2+}$, $Cu^{2+}$, and $Fe^{2+}$. Moreover, expression of sCAX2A in tomato plants did not show any significant alterations in their morphological phenotypes. Unlike 35S::sCAX1 construct, sCAX2A antiporter gene driven by 35S promoter can be a valuable tool for enriching $Ca^{2+}$ contents in the tomato fruit without additional accumulation of the undesirable cations.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.263-270
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• 2021

This experiment was carried out to determine the effect of CaCl₂ foliar spraying on the inhibition of blossom-end rot (BER) in hot summer paprika (Capsicum annum L. 'Special') cultivation. The effect of CaCl₂ application was examined by the foliar application based on different fruit size, frequency, and spraying time. Also, it was investigated the occurrence and alleviation effect of BER symptom. Foliar application of CaCl₂ (Ca 0.4%) was conducted by treating a fruit and leaf at 4 to 9 nodes above the crown flowers of each plant with 350 mL per week from June 3 to July 1. When the CaCl₂ was sprayed at 7-day intervals for 4 weeks, the Ca content was the lowest in the fruit harvested with BER symptom in 11 to 20 mm of fruit width (FW). Four different regions in both BER symptom and normal fruits showed significant differences of Ca content, the highest was in pedicel, followed by stem-end, middle, and blossom-end. The Ca content increased sharply in normal paprika with 31-40 mm FW, in which Ca content was 78% higher than that of BER. Ca content in the middle and blossom-end of paprika over 21 mm in FW ranged 19.8% to 28.8% in normal fruits and 15.7% to 18.5% in BER, respectively. The incidence of BER increased rapidly by more than 60% in fruits with 31-40 mm FW. While there was no difference in fruit weight among the FW treatment, marketable yield rate was highest in the 21-30 mm FW, and the sugar content was high in the 11-30mm FW. When CaCl₂ was applied three times for 7 days to a paprika having a 21- 30 mm FW, the cell wall-bound (CWB) Ca content was the highest and the rate of BER was lowest with 6.3%. After 10 days of CaCl₂ foliar spray treatment, the CWB Ca content of paprika increased by 2.9 to 3.5 times compared to the control in all treatments. At 7 days after the CaCl₂ foliar spraying once a day at varying spraying time, the leaf burn observed from 9:30 a.m. to 17:00 p.m. and the proline content increased as the spraying time was delayed. Therefore, the CaCl₂ foliar spraying method for reducing of BER occurrence during paprika summer cultivation seems to be appropriate to spray 2-3 times at intervals of 3 days and before 8 a.m. at the time when the FW is 21-30 mm.

• The Korean Journal of Mycology
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• v.41 no.1
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• pp.38-41
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• 2013

In 2010 and 2011, gray mold was found on common fig (Ficus carica) fruit grown at the research field of Jeollabuk-do Agricultural Research and Extension Services, Korea. Gray mold symptoms on common fig fruit mainly occurred after harvest season until December. The typical symptom included brown water-soaked rot and fruit decay. The diseased fruit was covered by gray to brown colored conidiophore and conidia. The conidiophores were tree shape and measured $15-33{\times}2{\mu}m$. Conidia on conidiophore were ellipsoidal or lemon shape, colorless, single cell, and measured $7.3-14.6{\times}6.8-11.1{\mu}m$. The nucleotide sequences of the rDNA ITS region obtained from the pure culture of the gray mold on common fig were 100% similar to the sequences of the GenBank accession number HQ171052, EU519210, HQ171053, FN812726, HM849615, and EU563120 of B. cinerea isolates. In phylogenetic tree, the representative isolate was placed within same clade of B. cinerea. Based on the morphological characteristics and analysis of rDNA ITS sequence data, the fungus was identified as B. cinerea.

• Horticultural Science & Technology
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• v.17 no.6
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• pp.737-741
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• 1999

We surveyed the physiological disorders of fruit vegetables grown in the greenhouse in Kyungbuk province in 1998. Greenhouses used for cultivation were mostly single or multi-span iron pipe houses covered with polyethylene film. Single span greenhouses were used for strawberry, oriental melon and watermelon. Fifty six percent of the surveyed farms was a mono-cropping system for oriental melon and tomato. There were greenhouses used for successive cultivation for 10 years or more for strawberry and oriental melon in Koryeong and Seongju. Varieties of fruit vegetables cultivated were diverse, especially in cucumber and watermelon. In strawberry, malformed fruits were observed most frequently in March and the small fruits at late harvest period. Leaf chlorosis, stunt plants and runner outbreak were also found during the growing season. In tomato, occurrence of malformed fruits was severe from March to May, and occurrence of cracked fruits and blossom- end rot was also severe in October and November. The self topping and abnormal stem in tomato were problem in hydroponic cultures in August and November, respectively. Malformed cucumber fruits, such as curved, club shaped, irregular shaped and narrow necked, occurred at late season. Umbrella-shaped leaf in cucumber in summer were caused by calcium deficiency. Most serious disorders were fermented and malformed fruits occurring from March to May in oriental melon, and cracked fruits occurring from April to May in watermelon. At late growing stage of melons the leaf chlorosis occurred with complex symptoms of leaf disease. Growers had little knowledge on physiological disorders, and also on diagnose and measures to cure the disorders. Most growers pointed out that poor soil environment and temperature management in the greenhouse as the main causes of physiological disorders.

• The Korean Journal of Mycology
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• v.46 no.3
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• pp.345-351
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• 2018

A fungal isolate denoted NC14-264 was isolated from the soil in Jeongeup, Jeollabuk-do, Korea. Species in genus Plectosphaerella are pathogenic to several plant species, leading to fruit, root, and collar rot and collapse. In this study, a strain NC14-264 belonging to the Plectosphaerella was isolated from the soil and identified. Colonies were moderately grown, reaching 54 mm in diameter on potato dextrose agar, 49 mm on malt extract agar, and 55 mm on oatmeal agar at $25^{\circ}C$ after 10 days of incubation. Most Plectosphaerella species are distinguishable morphologically by irregular chlamydospores and different proportions of phialides and conidia. Based on morphological features and phylogenetic analysis using the internal transcribed spacer region and partial 28S rRNA gene sequences, the isolated fungus was identified as Plectosphaerella sinensis belonging to the Plectosphaerellaceae. This is the first report of P. sinensis in Korea.

• Research in Plant Disease
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• v.28 no.2
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• pp.69-81
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• 2022

This study was performed to screen the efficacy of antagonistic bacterial isolates from various sources against the bacterial fruit blotch (BFB) causing pathogen (Acidovorax citrulli) in cucurbit crops. In addition, plant growth promoting traits of these antagonistic bacterial isolates were characterized. Two thousand seven hundred ninety-four microorganisms were isolated from the collected samples. Molecular identification revealed two A. citrulli out of 2,794 isolates. In vitro antagonistic results showed that, among the 28 antagonistic bacterial isolates, 24 and 14 bacterial isolates exhibited antagonism against HPP-3-3B and HPP-9-4B, respectively. Antagonistic and growth promotion characterization of the antagonistic bacterial isolates were further studied. Results suggested that, 4 antagonistic bacteria commonly showed both antagonism and growth promotion phenotypes. Moreover, 3 isolates possessed growth promoting activities. Overall results from this study suggests that BFB causing bacterial pathogen (A. citrulli) was suppressed in in vitro antagonism assay by antagonistic bacterial isolates. Furthermore, these antagonistic bacterial isolates possessed growth promotion and antagonistic enzyme production ability. Therefore, data from this study can provide useful basic data for the in vivo experiments which ultimately helps to develop the eco-friendly agricultural materials to control fruit rot disease in cucurbit crops in near future.

• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.399-405
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• 2011

In this study, we evaluated the fruit quality indices and the incidence of physiological disorders of Korean new pear cultivar 'Whasan' to determine appropriate harvest time for exportation and to enhance storability and shelf-life of the fruits during simulated exportation and extending market environment under different temperature conditions. In the experiment of simulated exportation headed for North America including Canada and U.S.A., the fruits transported at $1^{\circ}C$ showed less weight loss than those of $5^{\circ}C$. Market temperature appeared as a key factor for keeping freshness of exported pear fruits rather than transportation temperature. Quality factors such as high flesh firmness and low incidence of fruit rot and physiological disorders including core breakdown and pithiness were attained at the fruits maintained at $18^{\circ}C$ when we compared with $25^{\circ}C$. The fruits of harvested early maturity at 135 day after full bloom showed 28.6 N of flesh firmness when the fruits stored at $1^{\circ}C$ of transportation and $18^{\circ}C$ of market temperature, while the fruits progressed $5^{\circ}C$ of transportation and $25^{\circ}C$ of market temperature dropped to 24.2 N during 30 days of shelf life. Also, a high incidences of physiological disorders and of fruit decay rates were obvious in the fruits distributed at $25^{\circ}C$ were observed approximately two times higher than the those of $18^{\circ}C$. Therefore, temperature management during marketing resulted as an important point for maintaining fruits quality in the process of pear fruit exportation.

• Journal of Practical Agriculture & Fisheries Research
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• v.16 no.1
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• pp.55-66
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• 2014

This study has been conducted to investigate the treatment time and concentration of GA₃ solution dipping for labor saving in 'Campbell Early' grapevine. The rachis growth at harvest was reduced by GA₃ solution dipping before 5 days flowering, and increased significantly by GA₃ solution dipping treatment at full bloom and after 5 days full bloom. GA₃ 5, 10, 20 mg·L^-1 dipping treatment before 5 days flowering and GA₃ 20 mg·L^-1 treatment of full bloom and after 5 days full bloom showed a rachis twist phytotoxicity symptom. The optimum GA₃ concentrations for rachis growth promotion without phytotoxicity were 5 mg·L^-1 and 10 mg·L^-1. The degree of compact berry, bloom, skin color, SSC and acidity at harvest by GA₃ solution dipping treatment time between concentration were not different from those of control. But the fruit berry weight was decreased by before 5 days flowering treatment when compared with control. There were no differences in full bloom and after 5 days full bloom treatment. The occurrence percent of berry cracking at before 5 days flowering and after 5 days full bloom treatment were significantly increased by GA₃ treatment. The bitter rot occurrence of berry at harvest was not affected by GA₃ treatment. Total rachis length of fruit cluster was increased by full bloom and 5 days after full bloom treatment. The length of rachis increased without reference to them position at full bloom and 5 days after bloom treatment. Accordingly, GA₃ 5 mg·L^-1 solution dipping treatment at full bloom and 5 days after full bloom were can be effectively for rachis growth promotion.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.444-451
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• 2022

Recently, long-term cultivation is becoming more common with the increase in tomato hydroponics. In hydroponics, it is very important to supply an appropriate nutrient solution considering the nutrient and moisture requirements of crops, in terms of productivity, resource use, and environmental conservation. Since seasonal environmental changes appear severely in long-term cultivation, it is so critical to manage irrigation control considering these changes. Therefore, this study was carried out to investigate the effect of irrigation volume on growth and yield in tomato long-term cultivation using coir substrate. The irrigation volume was adjusted at 4 levels (high, medium high, medium low and low) by different irrigation frequency. Irrigation scheduling (frequency) was controlled based on solar radiation which measured by radiation sensor installed outside the greenhouse and performed whenever accumulated solar radiation energy reached set value. Set value of integrated solar radiation was changed by the growing season. The results revealed that the higher irrigation volume caused the higher drainage rate, which could prevent the EC of drainage from rising excessively. As the cultivation period elapsed, the EC of the drainage increased. And the lower irrigation volume supplied, the more the increase in EC of the drainage. Plant length was shorter in the low irrigation volume treatment compared to the other treatments. But irrigation volume did not affect the number of nodes and fruit clusters. The number of fruit settings was not significantly affected by the irrigation volume in general, but high irrigation volume significantly decreased fruit setting and yield of the 12-15th cluster developed during low temperature period. Blossom-end rot occurred early with a high incidence rate in the low irrigation volume treatment group. The highest weight fruits was obtained from the high irrigation treatment group, while the medium high treatment group had the highest total yield. As a result of the experiment, it could be confirmed the effect of irrigation amount on the nutrient and moisture stabilization in the root zone and yield, in addition to the importance of proper irrigation control when cultivating tomato plants hydroponically using coir substrate. Therefore, it is necessary to continue the research on this topic, as it is judged that the precise irrigation control algorithm based on root zone-information applied to the integrated environmental control system, will contribute to the improvement of crop productivity as well as the development of hydroponics control techniques.