• Korean journal of applied entomology
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• v.26 no.2 s.71
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• pp.99-106
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• 1987

Three post-harvest fields each in four rice growing areas, Iri, Naju, Jinju and Taegu were randomly selected and surveyed during December 1986 to examine sclerotial density of Rhizoctonia solani overwintering in the field. Surface soil of $0.09m^2$ area was sampled in each field with three replications and sieved to collect sclerotia. Germiability and pathogenicity of collected sclerotia were examined in the laboratory. Number of sclerotia $({\times}10^6)/ha$ in Iri, Naju, Jinju, and Taegu was estimated from the sample as 2.7, 1.2, 0.7 and 0.6, respectively. Based on sample variance with simple random sampling in each area, number of sampling required for estimating average sclerotial density with the precision of 10% apart from a chance of 1 in 20 was calculated to 41, 132, 232, and 395 for Iri, Naju, Jinju and Taegu, respectively. Percentage of germination of sampled sclerotia on potato sucrose agar (PSA) ranged from 42 to 78% depending on the area, and averaged 60%. About 49% of the germinated sclerotia were pathogenic to a rice cultivar Jinheung that was used to test pathogenicity of the sclerotia. Proportion of viable sclerotia that have both germiability and pathogenicity was thus estimated to 0.29 of total sclerotia collected. R. solani cultures obtained from the sclerotia could be distinguished into three groups based on colony morphology on PSA. Size and number of sclerotia formed on PSA differed between group but were not associated with pathogenicity to Jinheung.

• Journal of Sericultural and Entomological Science
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• v.28 no.1
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• pp.43-53
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• 1986

Among many microbial pesticides, Bacillus thuringiensis is one of the most hopeful pesticide and some commercial products have been appearing on the market. Because these commercial products contain living spores and toxins of the organism, there is a danger that living spores of B. thuringiensis may be scattered by wind and cause a great damage in the sericulture areas. In order to avoide these risks it is desirable to select the strain which has low pathogenicity to the silkworm, and at the sometime being highly pathogenic to the pest insects. Thus this study has been carried out to acquire some basic informations about the procedure of desicable strain selection. Three strains of B. thuringiensis var. kurstaki, var. dendrolimus and var. aizawai were used for the pathogenicity test on the silkworm, Bombux mori and the fall webwarm, Hyphantria cunea. Those strains were investigated by the agarose gel electrophoresis patterns of plasmid DNA determine whether mutation had occured. Pathogenicity tests were carried out of using isolated crystal proteins and spore-crystal protein to mixtures of each strain, seperatively. In case of using spore-crystal protein mixture, the order of pathogenicity in varities of B. thuringiensis against B.mopri and H.cunea were kurstaki, aizawai, dendrolimus and kurstaki, dendrolimus, aizawai, respectively. But using isolated crystal proteins, dendrolimus had the highest toxicity to H. cunea and the lowest toxicity to B. mori among tested three strains. From the above results, dendrolimus was presumed the most desirable straing for using microbial pesticide.

• Journal of fish pathology
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• v.36 no.2
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• pp.277-286
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• 2023

Korean rockfish, Sebastes schlegelii, is a representative bony fish that belongs to the family Scorpaenidae and the order Scorpaeniformes. It has high ecological and economic value and is widely cultivated in many East Asian countries, including South Korea, Japan and China. One of streptococci, Streptococcus iniae, is Gram-positive cocci with a negative reaction for catalase and oxidase. The Korean rockfish shows clinical signs when infected with S. iniae, such as body darkening, bleeding, enlarged kidneys, blurred eyes, abdominal distension, etc., ultimately leading to death. The Korean rockfish causes significant economic losses every year in South Korea due to streptococcosis. In this study, we identified bacteria from the fish using polymerase chain reaction and conducted analyses of hemolytic activity and biochemical tests using API 20 STREP and API ZYM systems. Results of confirming the hemolytic activity (n=4) observed in alpha-type hemolysis (25%), beta-type hemol- ysis (50%), and gamma-type hemolysis (25%) of isolates. The biochemical test results exhibited sig- nificant variation among S. iniae. Additionally, we performed intraperitoneal injection with S. iniae in the fish and analyzed the phylogenetic tree using housekeeping genes of S. iniae, including cpsD, arcC, glnA, groEL, gyrB, mutS, pheT, prkC, rpoB, and tkt, via multilocus sequence typing (MLST). The lethal dose (LD₅₀) showed strong pathogenicity, such as 3.34 × 10 colony-forming unit (CFU)/ml for 23FBStr0601 strain and 7.16 × 10 CFU/ml for 23FBStr0602 strain. 23FBStr0603 strain showed relatively low pathogenicity at 1.73 × 10⁵ CFU/ml. The strains 23FBStr0601 and 23FBStr0602, which showed strong pathogenicity, clustered into one monophyletic group. The 23FBStr0603 strain showed weak pathogenicity and formed a monophyletic group with KCTC 3657.

• Journal of Veterinary Clinics
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• v.26 no.4
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• pp.391-394
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• 2009

An Asian water monitor Varanus salvator with physical wound due to bite which was subsequently infected with bacterium resulting to hemorrhage and pus in the skin blisters, abdominal distention and septicemia. Morganella morganii was isolated and identified from the blood and kidney of the reptile, and confirmed by PCR and biochemical tests. The sensitivity of isolated strains to different groups of antibiotics was also evaluated using the disc diffusion method. Pathogenicity test using M. morganii (SNUFPC-MM01) (1.6 ${\times}$ $10^{11}$CFU/mouse) to suckling and adult mice resulted to the death of all mice. This paper describes the first isolation of M. morganii from Asian water monitor in Korea.

• Research in Plant Disease
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• v.14 no.1
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• pp.64-67
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• 2008

In 2005 and 2007, petiole and root rot of Spathiphyllum spp. was occurred at commercial greenhouse during summer (June-September) in Koyang city and Yongin city, Kyunggi-do, Korea. The pathogenic fungus was isolated from diseased plants and the cultural and morphological chracteristic were observed. Conidia were rod in shape, 1-3 septa and $67.5-95.0{\times}4.8-6.5\;{\mu}m$ (av. $82.0{\times}6.0\;{\mu}m$) in size. The optimum temperature for the mycelial growth of the isolates was $27^{\circ}C$. According to result the pathogenicity test, first disease symptoms appeared five days after inoculation. On the basis of mycological characteristics and pathogenicity test on host plants, the fungus was identified as Cylindrocladium spathiphylli. This is the first report on Spathiphyllum spp. caused by C spathiphylli in Korea.

• Journal of fish pathology
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• v.10 no.2
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• pp.153-164
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• 1997

Characteristics and pathogenicity of Yersinia sp. strain isolated from diseased cultured olive flounder, Paralichthys olivaceous were studied. The causative organisms were identified as Yersinia sp. by biochemical and biophysical characteristics. The strain was named KF-1, and it showed the optimal growth rate at pH 9.0 and 1% NaCl. Total cell protein peptide bands of the Yersinia sp. KF-1 were between 14.4-100.6 Kd in molecular weight by the electrophoretic analysis, and a total of 28 bands appeared. The band found at 32.8 Kd in molecular weight was the major one of electrophoretic phase. In the pathogenicity test of the isolate to the flounder injecting with $1.0{\times}10^7$ cfu/fish 9 died out of 10 within 60 hrs, and in the group with $1.0{\times}10^7$ cfu/fish 5 died within 60 hrs. Thus the $LD_{50}$ was presumed to be $1.0{\times}10^7$ cfu/fish. In the drug sensitivity test KF-1 strain was sensitive to chloramphenicol, gentamycin, kanamycin, streptomycin and pefloxacin, and intermediate to erythromycin, and resistant to ampicillin, cephalothin, sulfamethoxazole/trimethoprim, tetracycline and vancomycin.

• The Korean Journal of Mycology
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• v.12 no.1
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• pp.27-33
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• 1984

Alternaria tenuis, Arthrobotrytis sp., Aspergillus spp., Cephalosporium sp., Cladosporium sp., Cylindrocarpon sp., Fusarium equiseti, F. moniliforme, F. semitectum, F. solani, Penicillium spp., Rhizopus sp. were saprophytic fungi and Cercospora kikuchii, Colletotrichum truncatum, Diaporthe phaseolorum var. sojae and Fusarium oxysporum were pathogenic fungi detected from 14 seed samples of soybean. Initial symptoms caused by C. kikuchii, C. truncatum, D. phaseolorum sojae and F. oxysporum on seedlings from naturally infected seed by the test tube agar method have been described and discussed. Soybean seeds infected with C. truncatum, D. phaseolorum sojae and F. oxysporum reduced germination of seeds and have influenced on the growth of soybean seedling caused by C. kikuchii. Surface-sterilized soybean seedlings became diseased in the test tube agar artificially inoculated with C. kikuchii, C. truncatum and D. phaseolorum sojae isolated from naturally infected soybean seeds. F. oxysporum showed very weak pathogenicity. Seed disinfectants of Benlate-T, Homai, Tecto and Sisthane have effective to C. kikuchii, C. truncatum, D. phaseolorum sojae and F. oxysporum. Arasan, Captan, Busan-30 and Mercron were inferior to C. kikuchii but effective against others. Seed disinfectants treated in this experiment have increased seed germination campared with non-treatment.

• Korean Journal of Veterinary Service
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• v.14 no.2
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• pp.127-133
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• 1991

The present study was conducted to investigate the biochemical properties, pathogenicity, antimicrobial test, and serotype of E-coli isolated from slaughtered cattle during the period from March 1991 to May 1991. 1. A total of 12 E-coli isolates were isolated from 132 bile juice of slaughtered cattle. 2. All isolates were resistant to Erythromycin, Cephalothin, Neomycin and Lincomycin while the majority of them were susceptible to Trimethoprimsulfamethoxazol (67%), Chloramphenicol(58％), Gentamicin(58%), Ampicillin(17%), Kanamycin(9%) and Tetracycline (9%). 3. In the test of colicinogenecity and congo-red binding capability, 4(33%) isolates produced colicin, all isolates were congo-red negative. 4. The serotypes of isolated E-coli were identified as 008： K- (2 strain), 015： K- (1 strain), 08： K87： K88ab(1 strain), 0139： Kl2(1 strain), 0147: K89(1 strain), others(6 strains ) were autoagglutination.

• The Korean Journal of Mycology
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• v.49 no.3
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• pp.413-416
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• 2021

In July 2019, damping-off symptoms of young Fischer's ragwort (Ligularia fischeri) plants were observed in four vinyl greenhouses of a farmer located in Taebaek, Gangwon Province, Korea. This disease occurred in 20-30% of plants in the vinyl greenhouses investigated. Nine isolates of Rhizoctonia sp. were obtained from the diseased plants. All the isolates were identified as Rhizoctonia solani AG-2-2 (IIIB), based on morphological, cultural characteristics, and anastomosis test. Three isolates were used for artificial inoculation test on Fischer's ragwort. Pathogenicity of these isolates was confirmed on the plants with the inoculation tests. Damping-off symptoms observed on the inoculated plants were similar to those observed in the diseased plants in the vinyl greenhouses. This is the first report of R. solani AG-2-2 (IIIB) being the causative agent in damping-off in Fischer's ragwort.

• Research in Plant Disease
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• v.29 no.2
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• pp.184-187
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• 2023

In May 2020, we surveyed disease occurrence on vegetables grown in Seosan area, Korea. During the disease survey, white rot symptoms were observed in Korean wild chive (Allium monanthum) plants growing in fields. The symptoms occurred mainly in the seed bulb-producing fields of the crop. The above ground parts of the diseased plants displayed premature yellowing and dying of older leaves and stunting of the plants. The bulbs and roots of the diseased plants turned black and rotted. The disease occurred in a range of 1-60% in four of the eight fields surveyed. Three isolates of Sclerotium sp. were obtained from the bulb lesions of diseased plants. All isolates were identified as Stromatinia cepivora based on the morphological characteristics and phylogenetic analysis. Pathogenicity of the isolates on Korean wild chive was confirmed by artificial inoculation test. The lesions induced by the inoculation test were similar to those observed in the investigated fields. This is the first report of S. cepivora causing white rot in Korean wild chive.