• Research in Plant Disease
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• v.13 no.1
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• pp.57-60
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• 2007

A rhizopus soft rot caused by Rhizopus stolonifer occurred sporadically on grape in orchard in Gyeongsang-nam-do Agricultural Research and Extension Services and in Wholesale Market of Agricultural Products in Jinju city. The infected fruits were rapidly water-soaked, softened and eventually rotted, and the symptoms were initiated from wounds or cracks occurred at harvest time. Sporangiophores were $850{\sim}1,800{\mu}m$ in length and $12{\sim}23{\mu}m$ in width. Sporangia were globose or hemispheric and $80{\sim}190{\mu}m$ in size. The color of sporangia was white and cottony at first and gradually to brownish black, bearing abundant spores when it matured. Columella were hemispheric and $70{\sim}95{\mu}m$ in size. Sporangiospores were irregular round or oval, brownish-black streaked and $8{\sim}22{\times}6{\sim}10{\mu}m$ in size. The optimum temperature for mycelial growth of the fungus on PDA was 25$^{\circ}C$. On the basis of mycological characteristics and pathogenicity to grape (Vitis vinifera), the causal fungus was identified as Rhizopus stolonifer (Ehrenberg ex. Fr,) Lind. This is the first report of Rhizopus soft rot by R. stolonifer on grape (V. vinifera) in Korea.

• Research in Plant Disease
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• v.13 no.1
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• pp.61-65
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• 2007

English ivy (Hedera helix) in Araliaceae family is an evergreen climbing vine. A severe bacterial disease of English ivy was observed and investigated in January 2005. Initial symptoms on the leaves appeared as small water-soaked lesions on the lower surface. As the spots enlarged, the center became brown to brownish black and greenish-brown water-soaked, irregular margins surrounded the center, The spots developed into large irregular blotches, sometimes 5$\sim$10 mm in diameter, then coalesced. Finally, the water-soaked margins raised, dried out, became corky and broke in the center. A bacterial organism, isolated from the advancing margins of the lesions, was tested for its pathogenicity according to the Koch's postulates and biochemical and physiological tests identified the isolated bacterium as a Xanthomonas. The representative Xanthomonas strains (SL4821 and SL4822) isolated from English ivy were compared with a reference strain X. hortorum pv. hederae for fatty acid profiles, metabolic fingerprints and 16s rDNA sequences, showing that all outcomes were indistinguishable between the representative and reference strains. This is the first report of bacterial leaf spot of English ivy in Korea.

• Research in Plant Disease
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• v.13 no.1
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• pp.66-70
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• 2007

During 1997 and 1998, a new disease of lettuce (Lactuca sativa) was observed on greenhouse-grown plants in Kwangju and Kwangmyung. Lesions on leaves were irregular, small, pale green to black, water-soaked, and 2 to 5 mm in diameter, Coalescing lesions sometimes caused defoliation of older leaves. Isolations made from diseased leaves on yeast extract dextrose calcium carbonate agar yielded nearly pure cultures of a yellow pigmented bacterium typical of a xanthomonad. Two bacterial strains (SL0246 and SL1352) were purified and used for further tests. Pathogenicity of strains was confirmed on 5-week-old lettuce plants injected with bacterial suspensions containing $10^8$ cfu/ml of phosphate buffered saline. The representative Xanthomonas strains isolated from lettuce were compared with a reference strain X. campestris pv, vitians for fatty acid profiles and metabolic fingerprints using GN2 microplate, showing that all outcomes were indistinguishable between the representative and reference strains. This is the first report of bacterial leaf spot and dry rot of lettuce in Korea.

• Research in Plant Disease
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• v.13 no.1
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• pp.6-14
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• 2007

Root and basal stem rot disease occurred on moth orchid (Phalaenopsis spp.), Pung-nan (Neofinetia falcata) and Nadopung-nan (Aerides japonicum) grown in the farmers' greenhouses located in Namyangju Kyonggi province, Korea during 2005 to 2006. Wilting symptoms occurred on these orchard plants at initial stage and the infected plant leaves turned yellow to red. The discolored leaves were fallen down to lead to eventual death of the entire plant. A total of 59 isolates of Fusarium spp. was obtained from roots and leaf bases of the diseased plants. The cultural and morphological characteristics of isolated Fusairum spp. were identified as Fusarium oxysporum, F. proliferatum and F. solani. F. oxysporum and F. proliferatum were isolated from all these orchard plants but F. solani was isolated only from Phalaenopsis spp. Pathogenicity of the three Fusarium spp. was confirmed by artificial inoculation. Although F. oxysporum, F. proliferatum and F. solani cusing root rot disease in Phalaenopsis spp. have been reported in Korea, the pathogens in N. falcata and A. japonicum were not reported yet. Therefore, this is the first report on the root and stem rot of N. falcata and A. japonicum caused by F. oxysporum and F. proliferatum in Korea.

• Research in Plant Disease
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• v.13 no.2
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• pp.122-125
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• 2007

Leaf spot disease of Kalanchoe (Kalanchoe blossfeldiana) occurred at the farmer's vinly house in Gangseo-gu, Busan Metropolitan City, Korea, 2006. The diseased plants with typical symptom were collected and the casual agent were isolated. Its mycological characteristics and pathogenicity were examined. The results were as follows. The typical symptoms of the disease appeared as small brownish or dark brown spot on both sides of the leaves. The spots tended to develop from lower leaves. The spots gradually enlarged into conspicuous necrotic lesions 1-5 mm in diameter. Colonies of the causal fungus formed on potato dextrose agar were velvety, gray or grayish brown in color, Conidia were cylindrical or obclavate to oblong in shape, brown in color, $24{\sim}65\;{\times}\;12{\sim}23\;{\mu}m$ in size and had 1-4 transverse septa, The optimum temperature for growth of the fungus was about $25-30^{\circ}C$. Conidiophores were brown in color, $32{\sim}135\;{\times}\;4{\sim}8\;{\mu}m$ in size and had 1-7 transverse septa. The fungus was identified as Stemphylium lycopersici (Enjoji) Yamamoto based on its symptom and mycological characteristics. This is the first report of leaf spot of Kalanchoe caused by S. lycopersici in Korea.

• Research in Plant Disease
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• v.15 no.2
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• pp.112-119
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• 2009

We discovered two novel phytotoxins produced by the pathogenic fungus, Botrytis cinerea. Among the twenty-five B. cinerea isolates, which were obtained from various host plants in 1994 and 1996, twenty-two showed strong or moderate pathogenicity on five plants such as cucumber, tomato, red pepper, tobacco and Chinese cabbage. The culture filtrate of the B. cinerea 2-16 strain showed the most potent phytotoxic activity in a tobacco leaf-wounding assay. Two novel phytotoxins were isolated from the liquid cultures of B. cinerea 2-16 by ethyl acetate extraction, flash silica gel column chromatography, silica gel column chromatography, Sephadex LH-20 column chromatography, preparative TLC and subsequently preparative HPLC. Their chemical structures were determined to be 3-O-acetyl botcinol and 3-O-acetyl botcinolide, respectively, by mass and NMR spectral analyses. These two phytotoxins caused leaf necrosis in a leaf-wounding bioassay, and significant electrolyte leakage from leaf tissues of tobacco. In the two bioassays tested, 3-O-acetyl botcinol exhibited stronger phytotoxic activity than 3-O-acetyl botcinolide. This is the first report on the production of both 3-O-acetyl botcinol and 3-O-acetyl botcinolide from B. cinerea.

• Research in Plant Disease
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• v.23 no.2
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• pp.202-205
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• 2017

Pink rot appeared in greenhouse-grown sunflower (Helianthus annuus L.) in Jeonju, Korea. The symptoms appeared as brown discoloration of sunflower head and progressed into stem in advanced stage. In order to investigate the causal organism of this disease, we isolated a fungus from the infected seeds and maintained the isolated fungal culture on potato dextrose agar medium. Conidiophores were simple or branched, 62.5 to $123.1{\mu}m$ long. Conidia were produced in basipetal chains, ellipsoidal to pyriform with oblique and prominent truncate basal scars, two-celled, hyaline and measured $10.2-21.4{\times}7.5-12.6{\mu}m$. The fungus was inoculated to a new sunflower plant and showed the typical blight on the leaves. Study of morphological characters, pathogenicity tests and sequence analysis revealed that the isolated fungus is confirmed to be Trichothecium roseum. To our knowledge, this is the first report of pink rot on sunflower caused by T. roseum in Korea.

• Korean Journal of Poultry Science
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• v.31 no.2
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• pp.119-128
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• 2004

Highly Pathogenic Avian Influenza (HPAI) is a very acute systemic disease in poultry, particularly in chickens and turkeys caused by HPAI viruses. An outbreak of HPAI caused by subtype H5N1, was first reported in a broiler breeder farm on December 10, 2003 in Korea, although there had been twenty one outbreaks of the disease reported in the world before. Since mid-December 2003, eight Asian countries have confirmed outbreaks of HPAI due to the same subtype. The outbreak has also resulted in at least twenty three fatal human cases in Vietnam and Thailand as of May 17, 2004 according to the WHO. Regarding the first outbreak of recent Asian HPAI, it has been suspected that some Asian countries with the exception of Korea and Japan veiled the fact of HPAI outbreaks since the last half of 2003, even though it was first reported in Korea. There have been total nineteen outbreaks of HPAI among chicken and duck farms in 10 provinces in Korea since Dec. 2003 and approximately 5,280,000 birds were slaughtered from 392 farms for eradication of the disease and preemptive culling. The origin of the H5Nl HPAI virus introduced into the country are unknown and still under epidemiological investigation. Current status of outbreaks and characteristics of HPAI will be reviewed and discussed on the basis of genetic, virological, clinicopathological, and ecological aspect, as well as future measures for surveillance and prevention of the disease in Korea.

• Journal of radiological science and technology
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• v.43 no.5
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• pp.359-365
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• 2020

This study aimed to investigate the causes of bacterial growth to prevent infection caused by ultrasound gel and gel containers in contact with patients during ultrasonography. To investigate bacterial contamination during manufacturing or storage, we cultured ultrasound gels originally supplied from three manufacturers. To analyze bacterial growth according to the lapse of time and frequency of use of the ultrasound gel container, the gel and container were cultured at regular intervals every week for 4 weeks. In addition, to determine the source of infection, the examiner's hand was inspected with hand plate and the degree of bacterial contamination was measured before the test. As a result of the study, bacteria were not detected in the gel provided at the initial supply, and in the gel and gel container used repeatedly for 4 weeks, the same bacteria residing on the skin were identified in the examiner's hand, such as Staphylococcus epidermidis, Micrococcus luteus, Leuconostoc mesenteroid spp cremoris, Kocuria rhizophila, and etc. Separated strains were classified as those of the low- or non-pathogenicity; however, most of these strains may render fatal consequences to patients of lower level of immunity due to acquired tolerance to antibiotics. At week 1, when the number of tests was the highest, 44 colonies were identified, and at week 4, when the number of tests was the lowest, 4 colonies were identified. As r=0.994, it was found that the number of colonies increased as the number of tests increased. In conclusion, it was confirmed that the cause of the infection was not the ultrasound gel, but the examiner's hand. The ultrasound gel or gel container may be contaminated by skin flora of examiner's hands, which can cause opportunistic infection in patients with low immunity. The ultrasound gel or gel container may be contaminated by skin flora of examiner's hands, which can cause opportunistic infection in patients with low immunity. Therefore, it was confirmed that thorough hand disinfection was necessary to block healthcare-associated infections.

• Korean Journal of Veterinary Research
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• v.35 no.1
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• pp.149-158
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• 1995

The purpose of the present study was to understand the pathogenesis of infections in piglets inoculated with C parvum isolated from mice alone and combined with porcine rotavirus (S-80). Thirteen 10-day piglets were divided in four groups; Three, A group, were only given by C parvum. Four, B group, were orally administrated with firstly porcine rotavirus and then C patvum. Three, C group, were orally inoculated with porcine rotavirus alone. The rest, D group, were used as controls. During the experiment, there were daily recorded clinical signs including diarrhea to each pig. According to the periodic intervals for necropsy, all pigs were sacrificed from 4 to 12 days after the final inoculation of C parvum. Location and distribution of two pathogens, C parvum and rotavirus, in the intestinal mucosa of piglets tested were examined by pathological and immunohistological means. In addition, parasitological test using the feces of piglets was applied for the detection of cryptosporidial oocysts as well. A group showed diarrhea from 4 to 6 days post-inoculation(PI) and also discharged C parvum oocysts in feces during the day 4 to 7 PI. In tissue sections of jejunum and ileum, cryptosporidial oocysts were observed a few on the top of villi with slightly fusion. B group represented sign of diarrhea and discharge of oocysts from 2 to 11 days PI. There were some cryptosporidial oocysts both in the jejunal lumen and in the lumen of mucosal glands. As progressed, oocysts were most commonly distributed on the tip of villi of jejunum. Histopathologically there were also mild to moderately fused, attenuated focal desquamated, congested villi and mononuclear cell infiltration of varying degrees in the lamina propria of small intestine and colon at the day 4 and 7 PI. C group showed slightly to mildly attenuated and fused top of villi and mildly mucosal congestion. D group as controls was grossly and histopathologically normal in all parts of intestine. The present results indicate that the piglets inoculated with C parvum only are certainly milder in pathogenesis including duration of clinical course and severity of lesion than those in piglets concurrently infected with porcine rotavirus and C parvum. Also the strain (VRI-CN91) of C parvum used in the study has very low pathogenicity to occur enteritis of piglets.