• Journal of Ginseng Research
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• 제38권2호
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• pp.136-145
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• 2014

Background: This study aimed to develop a biocontrol system for ginseng root rot caused by Fusarium cf. incarnatum. Methods: In total, 392 bacteria isolated from ginseng roots and various soils were screened for their antifungal activity against the fungal pathogen, and a bacterial isolate (B2-5) was selected as a promising candidate for the biocontrol because of the strong antagonistic activity of the bacterial cell suspension and culture filtrate against pathogen. Results: The bacterial isolate B2-5 displayed an enhanced inhibitory activity against the pathogen mycelial growth with a temperature increase to $25^{\circ}C$, produced no pectinase (related to root rotting) an no critical rot symptoms at low [$10^6$ colony-forming units (CFU)/mL] and high ($10^8CFU/mL$) inoculum concentrations. In pot experiments, pretreatment with the bacterial isolate in the presumed optimal time for disease control reduced disease severity significantly with a higher control efficacy at an inoculum concentration of $10^6CFU/mL$ than at $10^8CFU/mL$. The establishment and colonization ability of the bacterial isolates on the ginseng rhizosphere appeared to be higher when both the bacterial isolate and the pathogen were coinoculated than when the bacterial isolate was inoculated alone, suggesting its target-oriented biocontrol activity against the pathogen. Scanning electron microscopy showed that the pathogen hyphae were twisted and shriveled by the bacterial treatment, which may be a symptom of direct damage by antifungal substances. Conclusion: All of these results suggest that the bacterial isolate has good potential as a microbial agent for the biocontrol of the ginseng root rot caused by F. cf. incarnatum.

• 식물병연구
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• 제6권1호
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• pp.6-9
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• 2000

1998년 수원, 성남, 양재, 대전의 비닐하우스에서 재배되고 있는 인삼고무나무(Ficus retusa), 황금대만고무나무(Ficus retusa \`Golden leaf\`), 벤자민고무나무(Ficus benjamina)에 새로운 세균병이 관찰되었다. 인삼고무나무의 뿌리에 무름증상을 보이는 세균병을 \"P.cichorii\"에 의한 인삼고무나무의 세균성뿌리썩음병\", 황금대만고무나무와 벤자민고무나무에 마름증상을 보이는 세균병을 \"P.viridiflava에 의한 황금대만고무나무와 벤자민고무나무의 세균성잎마름병\"으로 명명할 것을 제안한다.마름병\"으로 명명할 것을 제안한다.제안한다.

• The Plant Pathology Journal
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• 제22권1호
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• pp.103-106
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• 2006

In this biocontrol research, we evaluated disease suppressive effects of antagonistic bacterial strains ISE13 and KJ1R5 against Korean ginseng root rot caused by P. eaetorum. We also examined the effects of nutrient solution in the hydroponic culture system for Korean ginseng on biological activity of the bacterial strains. As results of dual culture tests of the bacterial strains on $V_{8}$ juice agar, the strain ISE13 showed antifungal activity against P. eaetorum and other plant pathogenic fungi, but the strain KJ1R5 did not. When their inhibitory effects against infection of P. eaetorum on the roots grown in either nutrient solution or water were tested, the strains ISE13 and KJ1R5 inhibited the disease severity of Korean ginseng roots only grown with water, compared to buffer-treated, inoculated controls. However, the nutrient solution used for hydroponic cultures of ginseng in pots caused higher levels of disease severity by the strains ISE13 and KJ1R5 from 418.8\%$ to 40.0\%$ and from 24.3\%$ to 45.0\%$, respectively. In this study, the bacterial strains ISE13 and KJ1R5 could be potentially biocontrol agents to suppress Korean ginseng root rot caused by P. eaetorum. However, more attention using nutrient solution in hydroponic cultures for Korean ginseng production should be applied in biocontrol of plant diseases using the antagonistic microorganisms.

• 한국식물병리학회지
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• 제3권3호
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• pp.236-238
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• 1987

A bacterial disease of elephant foot, Hydrosome rivieri Engl., was newly found in Taejon, Korea in August 1986. The affected plants showed symptoms of soft rot on leaf blades and petioles. Bacterial isolates from affected plants found to be pathogenic to elephant foots by antificial inoculation, producing similar symptoms with those produced naturally. The baterium was also pathogenic to carrot, Chinese cabbage, radish, potato and onion, and developed symptom of soft root on them. On the basis of bacteriological characteristics and pathogenicity, tested bacterium was identified as Erwinia carotovora subsp. carotovora and this disease was proposed to name 'Bacterial soft rot of elephant foot'.

• Journal of Ginseng Research
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• 제5권1호
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• pp.73-84
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• 1981

Effect of environmental factors and host on the growth and outbreak of various ginseng diseases was reviewed Environmental lectors included hydrogen ion concentration, moisture content, temperature, nutrition, and microbiol populations. Age of the ginseng plants in relation to several ginseng disease occurrence was also included in order to formulate the effective control measure for ginseng diseases. Damping-off caused by Rhizoctonia, Pythium, and Phytophthora, greymold by Botrytis, sclerotinia by Scleretinia, and phytophthora blight caused by Phytophthora were usually prevalent during the early growing season of ginseng when temperature is below 20$^{\circ}C$, while anthrac se caused by Colletotrichum, alternaria blight by Alternaria, and bacterial soft rot by Erwinia were so during the latter growing season when temperature is above 25$^{\circ}C$. However, the root rot incited by Fnarium and Cylindrocarpon caused severe damages throughout the growing season. Growth range of the temperature for a pathogen was highly related to the corresponding disease outbreak. Hydrogen ion concentration was highly related to the outbreak of sclerotinia, root rot, and red rot. Most severe outbreak of those diseases where the soil acidity was pH 4.7, pH 6.5- 7.5, and pH6.0-6.5, respectively. Nitrogen content in the soil was also related to outbreak of root rot and red rot. More red rot occurred where NH,-nitrogen is above 30 ppm and more root rot obtained when excessive nitrogen fertilizer applied. Yellow necrosis apparently was related to magnesium especially its ratio with potassium or calcium content in a soil. Fusarium Population showed significant .relations to missing rate of ginseng Plants in a Implanting ginseng field, while that of total bacteria showed similar relations in all ginseng field, However, in six year old ginseng fields, the more the Streptomyces population was, the less the Fusarium obtained. Consequently, less missing rate observed in a field where Streptomyces population was high. Damping-off, root rot, Rhytophthor a blight were mose severe on the nursery and on 2-3 years old ginseng plants, whereas sclerotinia, and grey cod, alteraria blight, anthracnose were severe on 4-6 years old ginseng plants. Root rot caused by Fusarium and Erwinia, however, was also severe regardless of the age of the plants when the roots were injured. Therefore, for the effective control of ginseng root rot most careful control of the disease during the early year should be rendered.

• 한국식물병리학회지
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• 제11권2호
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• pp.116-119
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• 1995

강원도 인제지역에서 집단재배되고 있는 치커리에 무름병이 관찰되었다. 병징 초기증사은 치커리 뿌리에서 무름증상을 나타내는 것을 시작으로 시간이 지남에 다라 병징부위가 점차적으로 확대되어 뿌리가 완전히 부패되었다. 뿌리의 연부증상은 치커리 지상부위를 마르게하여 결국은 고사시켰다. 병반부로부터 분리한 병원균은 생리, 화학적특성과 Biolog program의 결과에 따라 Erwinia carotovora subsp. corotovora로 동정되었다. E. carotovora subsp. carotovora에 의한 치커리의 무름병은 국내에서 보고된 바가 없기에, 본 세균에 의한 병을 "치커리 세균성무름병(bacterial soft rot of chicory)" 이라 명명할 것을 제안한다.

• The Plant Pathology Journal
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• 제36권3호
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• pp.244-254
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• 2020

Gom-chwi (Ligularia fischeri) is severely infected with Phytophthora drechsleri, the causal organism of Phytophthora root rot, an economically important crop disease that needs management throughout the cultivation period. In the present study, Phytophthora root rot was controlled by using bacterial isolates from rhizosphere soils collected from various plants and screened for antagonistic activity against P. drechsleri. A total of 172 bacterial strains were isolated, of which, 49 strains showed antagonistic activities by dual culture assay. In the seedling assay, six out of the 49 strains showed a predominant effect on suppressing P. drechsleri. Among the six strains, the ObRS-5 strain showed remarkable against P. drechsleri when treated with seed dipping or soil drenching. The ObRS-5 strain was identified as Enterobacter asburiae based on 16S ribosomal RNA gene sequences analysis. The bacterial cells of E. asburiae ObRS-5 significantly suppressed sporangium formation and zoospore germination in P. drechsleri by 87.4% and 66.7%, respectively. In addition, culture filtrate of E. asburiae ObRS-5 also significantly inhibited sporangium formation and zoospore germination by 97.0% and 67.6%, respectively. Soil drenched bacterial cells, filtrate, and culture solution of E. asburiae ObRS-5 effectively suppressed Phytophthora root rot by 63.2%, 57.9%, and 81.1%, respectively. Thus, E. asburiae ObRS-5 could be used as a potential agent for the biological control of Phytophthora root rot infecting gom-chwi.

• Journal of Microbiology and Biotechnology
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• 제4권1호
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• pp.68-74
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• 1994

A bacterial strain YB-70 which has powerful biocontrol activity against Fusarium solani causing plant root-rot resulting in considerable losses of many economical crops was isolated and selected from over 500 isolates from a ginseng rhizosphere in suppressive soil, and identified as a strain of Bacillus subtilis. In several biochemical and in vitro antibiosis tests on F. solani with culture filterates from B. subtilis YB-70, our data strongly indicated metabolites which mediated inhibition of the fungal growth were presumed to be heat-stable, micromolecular, and ethyl alcohol solutable antifungal substances. Suppression of root-rot by B. subtilis YB-70 was demonstrated in pot trials with eggplant (Solanum melongena L) seedlings. Treatment of the seedling with the bacterial suspension (1.7~1.9$\times$$10^5$ CFU/g) in F. solani-infested soil significantly reduced disease incidences by 68 to 76% after 25 to 30 days. The results supported that B. subtilis YB-70 have excellent potentials as a biocontrol agent.

• The Plant Pathology Journal
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• 제27권1호
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• pp.78-84
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• 2011

Antagonistic rhizobacteria, more specifically fluorescent pseudomonads and certain species of Bacillus, are known as biocontrol agents of fungal root diseases of agronomic crops. In this study, 144 bacteria were isolated from cucumber rhizosphere and screened as potential biological control agents against Phytophthora drechsleri, the causal agent of cucumber root rot, in vitro condition. Non-volatile compounds of 23 isolates showed noticeable inhibition zone (> 30%) against P. drechsleri, whereas volatile compounds of 7 isolates could prevent more than 30% of the mycelial growth of the fungus. All promising isolates, except of Pseudomonas flourescens V69, promoted significantly plant growth under in vitro condition. P. flourescens CV69 and V11 exhibited the highest colonization on the root. Results of the greenhouse studies showed that a reduction in disease incidence by use of some strains, and particularly use of strains CV6 and V11 as a soil treatment, exhibited a reduction in disease incidence so that suppressed disease by 85.71 and 69.39% respectively. Pseudomonas flourescens CV6 significantly suppressed disease in comparison to Ridomil fungicide. The use of mixture bacterial strains in the soil inoculated by the fungus resulting in falling down the most of the plants which didn't show significant difference with infected control soils without bacteria.

• Journal of Microbiology and Biotechnology
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• 제33권10호
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• pp.1299-1308
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• 2023

Carya cathayensis is an important economic nut tree that is endemic to eastern China. As such, outbreaks of root rot disease in C. cathayensis result in reduced yields and serious economic losses. Moreover, while soil bacterial communities play a crucial role in plant health and are associated with plant disease outbreaks, their diversity and composition in C. cathayensis are not clearly understood. In this study, Proteobacteria, Acidobacteria, and Actinobacteria were found to be the most dominant bacterial communities (accounting for approximately 80.32% of the total) in the root tissue, rhizosphere soil, and bulk soil of healthy C. cathayensis specimens. Further analysis revealed the abundance of genera belonging to Proteobacteria, namely, Acidibacter, Bradyrhizobium, Paraburkholderia, Sphaerotilus, and Steroidobacter, was higher in the root tissues of healthy C. cathayensis specimens than in those of diseased and dead trees. In addition, the abundance of four genera belonging to Actinobacteria, namely, Actinoallomurus, Actinomadura, Actinocrinis, and Gaiella, was significantly higher in the root tissues of healthy C. cathayensis specimens than in those of diseased and dead trees. Altogether, these results suggest that disruption in the balance of these bacterial communities may be associated with the development of root rot in C. cathayensis, and further, our study provides theoretical guidance for the isolation and control of pathogens and diseases related to this important tree species.