• The Korean Journal of Mycology
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• v.46 no.1
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• pp.83-90
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• 2018

Melon powdery mildew, caused by Podosphaera fusca, is one of the serious diseases of melon plant in Korea. In this study, we evaluated the effect of selected antagonistic bacteria on the inhibition of mycelial growth of various plant pathogens, and control of melon powdery mildew. Based on the 16S rDNA and gyrA gene sequences, the selected antagonistic bacteria, M09, M70, and M99-1, were identified as Bacillus velezensis. These bacteria not only inhibited the mycelial growth of 47~69% in various plant pathogens, but also significantly reduced the incidence of powdery mildew. The three strains selected in this study could be used as potential biological control agents for various plant diseases as well as melon powdery mildew.

• Korean Journal Plant Pathology
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• v.12 no.2
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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.

• Research in Plant Disease
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• v.12 no.3
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• pp.254-259
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• 2006

Bacillus spp. isolated from mushroom medium wastes were evaluated for their biocontrol potentials on control of Sclerotinia rot of lettuce. The Bacillus isolates were more effectively obtained from waste suspension when directly added into nutrient agar(NA) medium than plating on the agar medium. Totally 42 isolates obtained from the wastes B23 and B42 showed highest antifungal activity against eight fungal pathogens such as Sclerotinia sclerotiorum, Rhizoctonia solani, Pythium ultimum, Phytophthora capsici, Fusarium oxysporum, Colletotrichum gloeosporioides, Cladosporium cucumerinum, and Botrytis cinerea and B23 and B42 were finally selected for further studies. Optimal concentration of the isolates was $10ml(10^7cfu/ml)$ to suppress the Sclerotinia rot of lettuce. Supplements such as starch, glycerol, and egg-yolk successfully maintained the bacterial population for 30 days in vitro and increased bio-control potentials against the disease. The bacterial isolate B23 alone showed 72% control value, furthermore it presented 95% control value when supplemented with 0.2% of starch, glycerol, and egg-yolk. The promising Bacillus isolates B23 and B42 were identified as Brevibacillus brevis and Bacillus stearothermophillus, respectively, based on morphological and physiological characteristics according to API database.

• The Korean Journal of Pesticide Science
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• v.2 no.2
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• pp.97-101
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• 1998

Agrobacterium vitis causes a crown gall disease in grapevine and that is one of the major hindrances for the wide cultivation and production of grapevine. We studied the possibility of biological control using selected biological control agent. One isolate from the infected soil, named as strain 27, was able to inhibit the biovar 1; A. tumefaciens C58 and Ach5, biovar 2; A. rhizogenes 13264, and biovar 3; A. vitis, in vitro and in vivo test. The putative biological control agent, A. radiobacter strain 27 was carrying the plasmid and the size of isolated plasmid was very similar to that of pAgK84 of A. radiobacter K84.

• Microbiology and Biotechnology Letters
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• v.39 no.3
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• pp.287-293
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• 2011

The purpose of this study was to isolate and characterize fungal deteriogens, which induce discoloration of the cement tunnel, and calcite forming bacteria (CFBs), which have antifungal activity against fungal deteriogens. Isolation of mold, bacteria and yeast was performed using several solid media and partially identified using internal transcribed spacer (ITS); 5.8S rRNA gene sequencing and 16s rDNA sequencing. A total of 19 microbial strains were identified with the most widely distributed fungal strain being Cladospirum sphaerospermum. In addition, five bacteria derived from the tunnel were identified as CFBs. Amongst the latter, Bacillus aryabhatti KNUC205 exhibited antifungal activity against Cladospirum sphaerospermum KNUC253 and Aspergillus niger KCTC6906 as concentrated filtered supernatants.

• The Korean Journal of Mycology
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• v.20 no.3
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• pp.259-268
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• 1992

Fifty-three actinomycetes antagonistic to Phytophthora capsici and Magnaporthe grisea were isolated from rhizosphere soils in six pepper-growing areas and ashore soils. Thirty-two antagonistic actinomycetes, showing inhibition zone larger than 5 mm, were classified into 20 groups according to their colony morphology and color. The antagonistic activity against P. capsici greatly varied, which showed inhibition zone sizes in the ranges from 5.7 to 17.5 mm on V-8 juice agar and from 2.5 to 17 mm on tryptic soy agar. The antagonistic activity of some actinomycetes tested was remarkably different between the two test media. The antagonists showed a relatively broad antifungal spectrum, but their antibacterial activity was negligible, except for Pseudomonas solanacearum. Butanol extracts of culture filtrates from antagonistic actinomycetes inhibited mycelial growth of P. capsici and M. grisea, thereby confirming strongly antibiotic production in culture. Culture filtrates of some antagonistic actinomycetes completely inhibited Phytophthora blight in pepper plants.

• Research in Plant Disease
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• v.29 no.4
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• pp.405-413
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• 2023

Bacterial blight of carrot caused by Xanthomonas hortorum pv. carotae (Xhc) is one of the serious diseases of carrot, of which control measures has not been still established in the domestic farm. In this study, in order to select effective sterilizer for bacterial blight of carrots, three antibiotics such as streptomycin, oxolinic acid, kasugamycin, two copper compounds like copper hydroxide and copper sulfate basic and three rhizobacteria Burkholderia gladioli MRL408-3, Pseudomonas fluorescens TRH415-2 and Bacillus cereus KRY505-3 were selected to investigate their direct antibacterial effects using artificial media, aiming to identify effective pesticides against Xhc. Among them, treated medium with antibiotics such as streptomycin, oxolinic acid, and the antagonistic rhizobacteria MRL408-3 were formed inhibition zone. The agrochemicals and the rhizobacteria MRL408-3, which showed antibacterial effects on carrot leaves, pre-treated on the carrot leaves and then inoculated with Xhc. High control effects were shown on the carrot leaves pre-treated with both streptomycin and oxolinic acid. Scanning electron microscopy images of the carrot leaf surfaces showed that the population of bacteria decreased significantly on leaves pre-treated with streptomycin and oxolinic acid. From these results, it can be inferred that antibiotics like streptomycin and oxolinic acid exhibit superior control effects compared to other agents. This study provides valuable insights towards establishing an effective control system for bacterial blight of carrot.

• Research in Plant Disease
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• v.16 no.2
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• pp.158-162
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• 2010

Four promising biocontrol agents against Phytophthora capsici were selected from 507 bacterial isolates collected from rhizosphere soils and roots of pepper plants. In vitro experiment, these four biocontrol agents inhibited mycelial growth, germination of cystospores, and formation of zoosporangia and zoospores of Phytophthora capsici. In the pot experiment, the four biocontrol agents showed control efficiency higher than 70%. In greenhouse experiment, the isolates G28-6 gave the control value of 79.4%. These four biocontrol agents successfully colonized in the population density beyond 105 cfu/g on roots of pepper in vitro. The isolates G28-6 was identified as Pseudomonas aurantiaca, based on its cultural, morphological, and biochemical characterization and 16S rRNA gene sequence analysis.

• Horticultural Science & Technology
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• v.19 no.4
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• pp.591-595
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• 2001

This study was conducted to find out the proper chemicals and doses for controlling the bulb disease of Lilium Oriental hybrids 'Capablanca' and 'Marco Polo' cultivars during storage, and to ascertain any disadvantage of the treatment on shoot growth and flower development. Bulbs of 'Casablanca' and 'Marco Polo' cultivars were dipped in some fungicide solutions, including azoxystrobin, benomyl+thiram, and prochloraz, and culture broth of antagonistic bacteria for one hour. The rot was apparently inhibited by azoxystrobin and prochloraz solution dippings and it was not by benomyl+thiram in bulbs produced domestically. To improve physiological integrity, calcium chloride was treated. However, this treatment had no positive effects on bulb rot of lily. When bulbs were dipped in one-fifth of diluted broth. But the bulb rot was inhibited effectively as compared with untreated during storage. Benomyl+thiram and that with calcium inhibited the sprouting in 'Casablanca' and 'Marco Polo' cultivars during cultivation. Calcium and benomyl+thiram treatments decreased growth of leaf and flower but with no statistically significant difference. Other fungicidal materials treated to bulbs showed no effect on vegetative growth and flower quality.

• Korean Journal of Organic Agriculture
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• v.15 no.1
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• pp.93-108
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• 2007

In order to find a solution to protect pigs from bacterial diarrhea and the nasty smell in stalls which are the most trouble, we composed a bio-formula with Stretococcus thermophilus, Bacillus amyloliquifaciens and Bacillu subtilis. The antagonistic microbe Bacillus amyloliquifaciens can control the growth of Salmonella typhimurium KCTC 1926, Escherichia coli O-157, Listeria and Staphylococcus. S. thermophilus from pig's stomach can live in gastric juice so it also control germs. They worked in its living cell state and its culture fluid. As a result of feeding with piglings, it showed effects of preventing diarrhea and increasing the weight.