• Mycobiology
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• 제28권3호
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• pp.127-129
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• 2000

During the study of soil mycoflora in Jinju-shi in 1997, a dematiaceous hyphomycete, Gonytrichum macrocladum, was isolated using the soil dilute plating method. The isolate was recovered with very low frequencies and recorded for the first time in Korea. illustrated descriptions are presented for the isolate examined in the present study.

• The Plant Pathology Journal
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• 제22권4호
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• pp.348-352
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• 2006

Barley mild mosaic virus(BaMMV) is a soilborne Bymovirus vectored by root-infecting fungus, Polymyxa graminis. Mechanism of cultivar's resistance to BaMMV in field tests are difficult to assess since resistance could be either due to the virus or to P. graminis, or both. Whereas, available mechanical inoculation methods for BaMMV and other related viruses are labor intensive, give inconsistent results and generally result in low infection rates. Inoculation method using stick with gauze(SWG) was developed for BaMMV. The improved method proved to be simple, efficient, and reliable. The infected leaf tissues were preserved by drying in a frozen state under high vaccum(freeze dried barley infected leaves) to circumvent reduction of virus infectivity during storage. Five Korean barley cultivars were mechanically inoculated with BaMMV-infected sap by the improved method. Infection rates obtained were compared with natural infection. Cultivar Naehanssalbori showed resistance to BaMMV in the field trials but was found highly susceptible in the greenhouse tests by mechanical inoculation, indicating that the field resistance may be possibly due to resistance to P. graminis.

• Journal of Microbiology and Biotechnology
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• 제26권10호
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• pp.1755-1764
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• 2016

The application of Bacillus sp. in the biological control of plant soilborne diseases has been shown to be an environmentally friendly alternative to the use of chemical fungicides. In this study, the effects of bioorganic fertilizer (BOF) fortified with Bacillus amyloliquefaciens SQY 162 on the suppression of tomato bacterial wilt were investigated in pot experiments. The disease incidence of tomato wilt after the application of BOF was 65.18% and 41.62% lower at 10 and 20 days after transplantation, respectively, than in the control condition. BOF also promoted the plant growth. The SQY 162 populations efficiently colonized the tomato rhizosphere, which directly suppressed the number of Ralstonia solanacearum in the tomato rhizosphere soil. In the presence of BOF, the activities of defense-related enzymes in tomato were lower than in the presence of the control treatment, but the expression levels of the defense-related genes of the plants in the salicylic acid and jasmonic acid pathways were enhanced. It was also found that strain SQY 162 could secrete antibiotic surfactin, but not volatile organic compounds, to suppress Ralstonia. The strain could also produce plant growth promotion compounds such as siderophores and indole-3-acetic acid. Thus, owing to its innate multiple-functional traits and its broad biocontrol activities, we found that this antagonistic strain isolated from the tobacco rhizosphere could establish itself successfully in the tomato rhizosphere to control soilborne diseases.

• Journal of Microbiology and Biotechnology
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• 제14권3호
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• pp.498-502
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• 2004

The current study was conducted to monitor the possibility of the gene transfer among soil bacteria, including the effect of drift due to rain and surface water, in relation to the release of genetically modified organisms into the environment. Four types of bacteria, each with a distinct antibiotic marker, kanamycin-resistant P. fluorescens, rifampicin-resistant P. putida, chloramphenicol-resistant B. subtilis, and spectinomycin-resistant B. subtilis, were plated using a small-scale soil-core device designed to track drifting microorganisms. After three weeks of culture in the device, no Pseudomonas colonies resistant to both kanamycin and rifampicin were found. Likewise, no Bacillus colonies resistant to both chloramphenicol and spectinomycin were found. The gene transfer from glyphosate-tolerant soybeans to soil bacteria, including Rhizobium spp. as a symbiotic bacteria, was examined by hybridization using the DNA extracted from soil taken from pots, in which glyphosate-tolerant soybeans had been growing for 6 months. The results showed that 35S, T-nos, and EPSPS were observed in the positive control, but not in the DNA extracted from the soilborne microorganisms. In addition, no transgenes, such as the 35S promoter, T-nos, and EPSPS introduced into the GMO soybeans were detected in soilborne bacteria, Rhizobium leguminosarum, thereby strongly rejecting the possibility of gene transfer from the GMO soybeans to the bacterium.

• 식물병과 농업
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• 제1권1호
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• pp.19-29
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• 1995

A microbial product composed of three antagonistic fungal isolates (Aspergillus sp., Penicillium sp. and Trichoderma sp.) and three bacterial isolates (Arthrobacter sp., Bacillus sp., and Pseudomonas sp.) was tested for the control of Pythium blight caused by Pythium sp., brown patch by Rhizoctonia solani (anastomosis group(AG) 1-1) and large patch by R. solani (AG 2-2) of turfgrasses. Cultures of the antagonistic fungi and bacteria varied in the effectiveness in reducing disease severity of Pytium blight and brown patch on bentgrass. The antagonistic fungal and bacterial isolates were mixed and cultured at 20-$25^{\circ}C$ for 3 days in a growth medium, and the diluted solution of the microbial culture was applied under the field conditions after inoculation of the above turfgrass pathogens. The treated turfgrass was incubated at 28$^{\circ}C$ in a growth chamber. In this experiment, Pythium blight was almost completely controlled and brown patch was slightly decreased by the microbial product, while no control was observed in large patch of zoysiagrass. In zoysiagrass treated with the microbial culture, thatch accumulation was notably reduced.

• 한국균학회지
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• 제11권2호
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• pp.99-101
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• 1983

Black root rot caused by Cylindrocladium crotalariae is one of the most serious soilborne disease in soybean. Plant height reduction of Hwangkeum Kong was 38% by the rotting of the whole main root and 9% by rotting of the half of the main root as compared with partial discoloration in the main root. Pod number per plant and seed weight were significantly reduced by the increase of the disease severity. Important yield components such as number of pods per plant and seed weight were negatively correlated with the soybean black root rot severity.

• 한국식물병리학회지
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• 제12권2호
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• pp.237-244
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• 1996

길항곰팡이 3종(Aspergillus sp. A101, Penicillium sp. B202, Trichoderma sp. C303), 길항세균 3종(Arthrobacter sp. AN303)또는 이들 모두의 혼합균주를 배양하여 creeping bentgrass 양묘장에 처리하여 Pythium blight, brown patch 및 dollar spot의 방제효과를 조사하였다. 또한 길항미생물 6종의 배양액을 살균제와 병용하여 그린에 살포하여 이들 토양병에 대한 방제효과를 조사하였다. 양묘장에서는 미생물의 종류에 관계없이 Pythium blight 억제효과가 커 3회 이상 미생물제 처리시 병이 전혀 발생하지 않았다. 그러나 brown patch와 dollar spot은 미생물제에 의한 방제효과가 크지 않았으며, 살균제에 의해 효과적으로 방제되었다. 미생물제와 살균(Pythium blight 방제용 살균제 제외)를 병용하여 처리한 그린에서는 살균제 단독처리와 비교할 때 brown patch는 유의적으로 억제되었고 Pythium blight와 dollar spot은 차이가 없었다.

• 식물병연구
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• 제10권2호
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• pp.87-93
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• 2004

Rhizome rot of ginger, caused by Pythium myriotylum, a major limiting factor for its production, has occurred annually, but become severe, especially in hot and humid years with frequent rainfalls in Korea. Most studies on rhizome rot have been carried out since 1980s in the National Institute of Agricultural Sciences and Technology, Honam Crop Experimental Station and Choongnam Provincial Rural Development Administration. Many aspects of rhizome rot, such as survey of the disease incidence, taxonomy, pathogenicity and physiology of pathogen, and ecology of soilborne inocula have been studied in the researches. However, intensive studies have been concentrated on management technologies of the disease including seed-rhizome disinfection, soil sterilization, evaluation of cultivar resistance, and fungicide application, and most developed technologies have been used in commercial farmings. In future, development of resistant varieties and simple soil disinfection technologies applicable in Korean condition and economically feasible fungicide application technology have to be developed for better management.

• 한국식물병리학회지
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• 제10권4호
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• pp.319-324
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• 1994

The monoxenic culture of the fungivorous nematode, Aphelenchus avenae, was applied for the control of soil-borne ginseng pathogens such as Fusarium solani and Rhizoctonia solani. Fungivorous nematode populations were measured in a field to examine relationships between the nematode populations and suppression of ginseng root diseases. Inoculation of A. avenae (5000 nematodes per petri-dish) reduced the colonization of the Fusarium mycelium on root discs of ginseng and carrot by 80.0% and 60.5%, respectively. A. avenae also significantly reduced the occurrence of damping-off of ginseng by R. solani pathogenic to ginseng, and no plant damage by the nematode was noted. In a 3-year-old ginseng field infested with Cylindrocarpon destructans, plant missing caused by root rot positively correlated to the density of potato rot nematode, Ditylenchus destructor, but it was reduced with the population of A. avenae, suggesting that A. avenae might inhibit the occurrence of ginseng root rot.

• 한국식물병리학회지
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• 제11권1호
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• pp.47-52
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• 1995

One hundred and thirty bacterial isolates with high chitinolytic activity on chitin agar media were isolated and identified. Most of the isolates were Aeromonas hydrophila (110 isolates), and the others were Serratia marcescens (11 isolates), Aeromonas caviae (3 isolates), Chromobacterium violaceum strain C-61 (2 isolates), Chromobacterium violaceum strain C-72 (1 isolate) and unknown species (3 isolates). Among them, C. violaceum strain C-61 had highest chitinolytic activity and fungal growth inhibition on PDA. This bacterium also inhibited the growth of Rhizoctonia solani, Sclerotinia scelrotiorum, Phytophthora capsici and Pythium ultimum, but it didn't inhibit the growth of Fusarium oxysprum and Fusarium solani. C. violaceum strain C-61 suppressed damping-off of eggplant caused by R. solani. Populations of the chitinolytic bacteria such as Aeromonas hydrophila, Serratia marcescens, Aeromonas caviae, Chromobacterium violaceum strain C-61 and Chromobacterium violaceum strain C-72 introduced into R. solani-infested soil were continuously decreased until 20 days after treatment, but their populations except A. caviae were not changed significantly and maintained over 5$\times$104 CFU per g of soil thereafter.