• The Plant Pathology Journal
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• 제20권4호
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• pp.289-292
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• 2004

The population of Ralstonia solanacearum (Rs) in soil is very important as a primary inoculum source of bacterial wilt in tobacco fields. To investigate the population of Rs, physical properties and chemical components during the tobacco growing season, soil samples were taken from the fifteen fields which were located in the flue-cured tobacco growing area, Ansung, Kyunggi province and Wonju, Kangwon province. Two fields of the fifteen were bacterial wilt free. Six fields had less than 10% plants being diseased and seven over 10%. The Rs population level determined by using SMSA medium generally showed an up-and-down pattern being low in May, high in Jun and July and low in August. The soil population in May and June showed a positive correlation with the incidence of bacterial wilt (r=0.571$^*$, r=0.688$^{**}$), but P$_2O_5$, content of soil was negatively correlated with the disease incidence (r=-0.539$^*$). These results suggest that Rs population in soil examined in May or in June, and the P$_2O_5$ content in soil should be key factors to determine the bacterial wilt potential of tobacco fields.

• The Plant Pathology Journal
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• 제38권3호
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• pp.203-211
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• 2022

Bacterial wilt, which is a major soil-borne disease with widespread occurrence, poses a severe danger in the field of tobacco production. However, there is very limited knowledge on bacterial wilt-induced microecological changes in the tobacco root system and on the interaction between Ralstonia solanacearum and fungal communities in the rhizosphere soil. Thus, in this study, changes in fungal communities in the rhizosphere soil of tobaccos with bacterial wilt were studied by 18S rRNA gene sequencing. The community composition of fungi in bacterial wilt-infected soil and healthy soil in two tobacco areas (Gengma and Boshang, Lincang City, Yunnan Province, China) was studied through the paired comparison method in July 2019. The results showed that there were significant differences in fungal community composition between the rhizosphere soil of diseased plants and healthy plants. The changes in the composition and diversity of fungal communities in the rhizosphere soil of tobaccos are vital characteristics of tobaccos with bacterial wilt, and the imbalance in the rhizosphere microecosystem of tobacco plants may further aggravate the disease.

• 농약과학회지
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• 제15권3호
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• pp.298-302
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• 2011

국내에서 Ralstonia solanacearum에 의한 풋마름병은 토마토 재배에 심각한 피해를 주고 있다. R. solanacearum에 의한 풋마름병을 방제하기 위한 약제를 선발하기 위하여 5종 항생제를 이용하여 균에 대한 생장 억제 효과와 포장에서의 토마토 풋마름병 방제효과를 조사하였다 R. solanacearum에 대한 생장억제효과를 조사한 결과, streptomycin 수화제, oxytetracyclin streptomycin sulfate 수화제, oxolinic acid 수화제는 병원균에 대한 생육억제 효과가 우수하였다. 포장에서 토마토 풋마름병에 대한 방제효과 시험을 실시한 결과, copper hydroxide 수화제가 62.5%의 가장 높은 방제효과를 나타내었다. Copper hydroxide 수화제는 친환경유기농자재에 등록된 약제로서 관행 재배뿐만 아니라 토마토 친환경 재배시에도 풋마름병 방제에 사용할 수 있을 것이다.

• The Plant Pathology Journal
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• 제35권4호
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• pp.362-371
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• 2019

Plant phenotype is affected by a community of associated microorganisms which requires dissection of the functional fraction. In this study, we aimed to culture the functionally active fraction of an upland soil microbiome, which can suppress tomato bacterial wilt. The microbiome fraction (MF) from the rhizosphere of Hawaii 7996 treated with an upland soil or forest soil MF was successively cultured in a designed modified M9 (MM9) medium partially mimicking the nutrient composition of tomato root exudates. Bacterial cells were harvested to amplify V3 and V4 regions of 16S rRNA gene for QIIME based sequence analysis and were also treated to Hawaii 7996 prior to Ralstonia solanacearum inoculation. The disease progress indicated that the upland MM9 $1^{st}$ transfer suppressed the bacterial wilt. Community analysis revealed that species richness was declined by successive cultivation of the MF. The upland MM9 $1^{st}$ transfer harbored population of phylum Proteobacteria (98.12%), Bacteriodetes (0.69%), Firmicutes (0.51%), Actinobacteria (0.08%), unidentified (0.54%), Cyanobacteria (0.01%), FBP (0.001%), OD1 (0.001%), Acidobacteria (0.005%). The family Enterobacteriaceae of Proteobacteria was the dominant member (86.76%) of the total population of which genus Enterobacter composed 86.76% making it a potential candidate to suppress bacterial wilt. The results suggest that this mixed culture approach is feasible to harvest microorganisms which may function as biocontrol agents.

• 한국유기농업학회지
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• 제12권1호
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• pp.101-114
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• 2004

This study was carried out to clarify the effects of antagonistic microorganism, Bacillus sp. JC181 isolated from the greenhouse soil grown cucumber plants on the growth inhibition of plant pathogen, fusarium wilt (Fusarium oxysporum) occurred in cucumber plants in greenhouse. Antagonistic bacterial strains were isolated and were investigated into the antifungal activity of the antagonistic microorganism against fusarium wilt. Screened fourteen bacterial strains which strongly inhibited F. oxysporum were isolated from thc greenhouse soil grown cucumber plants, and the best antagonistic bacterial strain designated as JC181, was finally selected. Antagonistic bacterial strain JC181 was identified to be the genus Bacillus sp. based on the morphological and biochemical characterization. Bacillus sp. JC181 showed 58.2% of antifungal activity against the plant pathogen growth of F. oxysporum. By the bacterialization of culture broth and heated filtrates of culture broth, Bacterial strain, Bacillus sp. JC181. showed 91.2% and 260% of antifungal activity against F. oxysporum, respectivrly.

• The Plant Pathology Journal
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• 제26권2호
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• pp.178-184
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• 2010

Four major diseases of chili pepper including two fungal diseases, anthracnose (Colletotrichum acutatum) and Phytophthora blight (Phytophthora capsici), and two bacterial diseases, bacterial wilt (Ralstonia solanacearum) and bacterial spot (Xanthomonas campestris pv. vesicatoria), were investigated under future climate-change condition treatments in growth chambers. Treatments with elevated $CO_2$ and temperature were maintained at $720ppm{\pm}20ppm$ $CO_2$ and $30^{\circ}C{\pm}0.5^{\circ}C$, whereas ambient conditions were maintained at $420ppm{\pm}20ppm$ $CO_2$ and $25^{\circ}C{\pm}0.5^{\circ}C$. Pepper seedlings or fruits were infected with each pathogen, and then the disease progress was evaluated in the growth chambers. According to paired t-test analyses, bacterial wilt and spot diseases significantly increased by 24% (p=0.008) and 25% (p=0.016), respectively, with elevated $CO_2$ and temperature conditions. On the other hand, neither Phytophthora blight (p=0.906) nor anthracnose (p=0.125) was statistically significant. The elevated $CO_2$ and temperature accelerated the progress of bacterial wilt by two days and bacterial spot by one day compared to the ambient treatment. Temperature regime studies of the diseases without changes in $CO_2$ confirmed that the accelerated bacterial disease progress was mainly due to the increased temperature rather than the elevated $CO_2$ conditions.

• 한국미생물·생명공학회지
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• 제36권2호
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• pp.115-120
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• 2008

근권 미생물을 대상으로 뿌리에서의 집락 형성 실험, 풋마름병 방제 효과 그리고 화학 농약에 대한 내성을 검정하여 SKU48-2 균주를 선발하였다. SKU48-2균주는 균체 현탁액$(10^8CFU/ml)$을 처리하였을 때 60%이상의 풋마름병 방제 효과를 나타내었으며, 형태적, 생화학적 특성과 16S rDNA sequence 분석 결과 Bacillus subtilis SKU48-2로 동정되었다. 선발 균주 SKU48-2는 화학 농약에 대해 강한 내성을 가져 토양 내 잔류 농약에 의해 영향을 받지 않을 뿐만 아니라, 화학 농약과의 혼용에 의해서 저농약 사용이 가능하고 미생물제제 단독 사용 시 보다 높은 방제 효과를 기대할 수 있다. SKU 48-2균주가 액상의 배양액 상태에서는 4주 만에 생균밀도가 급격히 감소한 반면, talc, vermiculite와 peat등의 담체 사용 시는 생균밀도가 6개월 간 유지됨이 확인되어 고형 제제화의 기초를 마련하였다.

• 한국유기농업학회지
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• 제12권2호
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• pp.183-196
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• 2004

This study was carried out to screen and select the effects of antifungal bacterial strains which inhibit the growth of plant pathogen, Fusarium oxysporum(fusarium wilt) occurred in carnation plants in greenhouse. We isolated an effective bacterial strains and investigated into the antifungal activity of the antagonistic microorganism and it's identification. Twenty bacterial strains which strongly inhibited Fusarium oxysporum were isolated from roots of carnation plants and the soil in greenhouse, and the best antifungal bacteria designated as C121, was finally selected. Antagonistic bacterial strain, C121 was identified to be the genus Bacillus sp. based on the morphological, biochemical and cultural characterizations. The Bacillus sp. C121 showed 58.1% of antifungal activity against the growth of Fusarium oxysporum. By the bacterialization of the cultural broth and the heat bacterialization culture filtrate of it, Bacillus sp. C121 was shown 92.1% and 21.0% of antifungal activity, respectively.

• The Plant Pathology Journal
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• 제29권1호
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• pp.93-98
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• 2013

Bacterial wilt is a vascular wilt disease caused by Xanthomonas translucens pv. poae that infects Poa annua, a grass that is commonly found on golf course greens throughout the world. Bacterial wilt causes symptoms of etiolation, wilting, and foliar necrosis. The damage is most prevalent during the summer and the pathogen can kill turf under conditions optimal for disease development. Fifteen isolates of X. translucens pv. poae were collected from northern regions in the United States and tested for virulence against P. annua. All 15 isolates were pathogenic on P. annua, but demonstrated variable levels of virulence when inoculated onto P. annua under greenhouse conditions. The isolates were divided into two virulence groups. The first group containing four isolates generally resulted in less than 40% mortality following inoculation. The second group, containing the other eleven isolates, produced between 90 and 100% mortality following inoculation. These results suggest that differences in the virulence of bacterial populations present on a golf course may result in more or less severe amounts of observed disease.

• 한국연초학회지
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• 제15권2호
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• pp.137-144
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• 1993

The present study was conducted to compare the efficiency of individual plant selection for resistance to bacterial wilt with 30 dihaploid lines derived by anther culture and Nicotiana africana method in Fl and F2 generation from a cross between Bright Yellow 4 (BY4) and NC95. F2 dihaploid lines were selected from bacterial wilt disease resistant plants screened under the naturally infested filed conditions. The populations of FB - ADH and FB MDH derived from F2 individual plants with bacterial wilt resistance showed higher resistance to the disease than the populations of Fl - ADH and Fl - MDH, respectively, and no difference for the disease resistance appeared by the haploid deriving method within a generation.