• 한국균학회소식:학술대회논문집
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• 2016.05a
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• pp.25-25
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• 2016

Biological control has many advantages as a disease control method, particularly when compared with pesticides. One of the most important benefits is that biological control is an environmental friendly method and does not introduce pollutants into the environment. Another great advantage of this method is its selectivity. Selectivity is the important factor regarding the balance of agricultural ecosystems because a great damage to non target species can lead to the restriction of natural enemies' populations. The objective of this research was to evaluate the effects of several different bacterial isolates on the efficacy of biological control of soil borne diseases. White rot caused by Sclerotium cepivorum was reported to be severe disease of garlic and chive. The antifungal bacteria Burkholderia pyrrocinia CAB08106-4 was tested in field bioassays for its ability to suppress white rot disease. In field tests, B. pyrrocinia CAB08106-4 isolates suppressed white rot in garlic and chive, with the average control efficacies of 69.6% and 58.9%, respectively. In addition, when a culture filtrate of B. pyrrocinia CAB08106-4 was sprayed onto wounded garlic bulbs after inoculation with a Penicillium hirstum spore suspension in a cold storage room ($-2^{\circ}C$), blue mold disease on garlic bulbs was suppressed, with a control efficacy of 79.2%. These results suggested that B. pyrrocinia CAB08106-4 isolates could be used as effective biological control agents against both soil-borne and post-harvest diseases of Liliaceae. Chinese cabbage clubroot caused by Plasmodiophora brassicae was found to be highly virulent in Chinese cabbage, turnips, and cabbage. In this study, the endophytic bacterium Flavobacterium hercynium EPB-C313, which was isolated from Chinese cabbage tissues, was investigated for its antimicrobial activity by inactivating resting spores and its control effects on clubroot disease using bioassays. The bacterial cells, culture solutions, and culture filtrates of F. hercynium EPB-C313 inactivated the resting spores of P. brassicae, with the control efficacies of 90.4%, 36.8%, and 26.0%, respectively. Complex treatments greatly enhanced the control efficacy by 63.7% in a field of 50% diseased plants by incorporating pellets containing organic matter and F. hercynium EPB-C313 in soil, drenching seedlings with a culture solution of F. hercynium EPB-C313, and drenching soil for 10 days after planting. Soft rot caused by Pectobacterium carotovorum subsp. carotovorum was reported to be severe disease to Chinese cabbage in spring seasons. The antifungal bacterium, Bacillus sp. CAB12243-2 suppresses the soft rot disease on Chinese cabbage with 73.0% control efficacy in greenhouse assay. This isolate will increase the utilization of rhizobacteria species as biocontrol agents against soft rot disease of vegetable crops. Sclerotinia rot caused by Sclerotinia sclerotiorum has been reported on lettuce during winter. An antifungal isolate of Pseudomonas corrugata CAB07024-3 was tested in field bioassays for its ability to suppress scleritinia rot. This antagonistic microorganism showed four-year average effects of 63.1% of the control in the same field. Furthermore, P. corrugata CAB07024-3 has a wide antifungal spectrum against plant pathogens, including Sclerotinia sclerotiorum, Sclerotium cepivorum, Botrytis cinerea, Colletotrichum gloeosporioides, Phytophotra capsici, and Pythium myriotylum.

• The Plant Pathology Journal
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• v.17 no.3
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• pp.141-148
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• 2001

Postharvest decay of onion bulbs was examined by inspecting the commercial packages in the market or in storage. Bulb rot incidence was unexpectedly high, and onion bulbs with 1st quality grade were rotten most severely by 51%, followed by 32% for 2nd and 21% for 3rd grades. This indicates that larger bulbs had higher incidences of bulb rots. Major pathogens associated with basal and neck rots were Fusarium oxysporum and Aspergillus sp. or Botrytis allii, respectively, of which basal rot was most prevalent and damaging during storage. Among the epiphytic microorgani는 from onion plants, several Bacillus and Paenibacillus spp. and previously selected Pseudomonas putida and Trichoderma harzianum had inhibitory efficacy against bulb rot pathogens. Among these B. amyloliquefaciens BL-3, Paenibacillus polymyxa BL-4, and P. putida Cha 94 were highly inhibitory to conidial germination of F. oxysporum and B. allii. P. putida Cha 94, B. amyloliquefaciens BL-3, P. polymyxa BL-4, and T. harzianum TM were applied in the rhizoplane of onion at transplanting. Initially antagonist populations decreased rapidly during the first one month. However, among these antagonists, rhizoplane population densities of BL-3, Cha 94, and TM were consistently high thereafter, maintaining about 10$^4$-10$^{5}$ cells or spores per gram of onion root up to harvest time. The other bacterial antagonist BL-4 survived only for two months. TM was the most effective biocontrol agent against basal rot, with the number of rotten bulbs recorded at 4%, while that of the control was 16%. Cha 94 was effective for the first 20 days, but basal rot increased thereafter and had about the same control efficacy as that of BL-3 and BL-4. When the antagonists were applied to the topping areas of onion bulbs at harvest, TM was the most effective in protecting the stored onion bulbs from neck rotting. The second effective antagonist was BL-3. TM and BL-3 completely suppressed the neck rot in another test, suggesting that biocontrol of postharvest decay of onion using these microorganisms either at the time of transplanting or at harvesting may be promising.

• Korean Journal of Organic Agriculture
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• v.17 no.1
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• pp.83-94
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• 2009

This study was carried out to investigate the effect of application of spent mushroom compost(SMC) on soil chemical properties and tomato growth. After the mushroom has been harvested, the SMC contains a lot of organic material, different microorganism and high density of mushroom hypha. SMC of white button mushroom(Agaricus bisporus) contained diverse microorganisms including fluorescent Pseudomonas sp. and actinomycetes. These isolates showed strong antagonistic to bacterial wi1t(Ralstonia solanacearum) and fusarium wi1t(Fusarium oxysporum) of tomato. The growth and sugar content of tomato showed no significant difference with other treatments by stage of maturity. The EC, exchangeable K and Ca contents of the soil during growing stage were increased in comparison to those of farmhouse practice, but available phosphate decreased. Microbial population in the soil in all growing stages showed no significant difference with other treatments, but yield of tomato decreased in some way in comparison to farmhouse practice. As the result of analysis on chemical property of soil and plant growth and yield of tomato, it seems likely that SMC of white button mushroom(Agaricus bisporus) may be used as substitute of practice compost on cultivation of tomato.

• Journal of Life Science
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• v.16 no.1
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• pp.108-113
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• 2006

To compensate the problems of chemical assay in detoxification of recalcitrant and a practical approach in selection of bioremediation bacteria, a simple and rapid toxicity evaluation system was constructed based on Lumbricus rubellus. Long term-culture and specific equipment are not necessary, and semi-quantitative analysis of toxicity at sub-lethal concentration is possible by measuring of dose-dependent increased yellowish secreted compounds. When the toxicity of endosulfan, its metabolites and structurally related chemicals were measured for 24 h, the results were coincided with previous reports. Toxicity was found in endosulfan, endosulfan sulfate, aldrin, and dieldrin, respectively. Rapid and economic selection of endosulfan-detoxifying bacteria was possible using our system. Klebsiella pneumoniae KE-1, K. oxytoca KE-8 and Pseudomonas sp. KS-2P, reported endosulfan degrading bacteria, ameliorated the endosulfan toxicity, whereas E. coli, B. subtilis and other bacteria failed to protect the toxicity of endosulfan in L. rubellus. Our results suggest that the constructed system is useful to selection of microorganism as well as toxicity evaluation against toxic recalcitrants.