• Korean Journal of Organic Agriculture
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• v.6 no.1
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• pp.133-149
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• 1997

Recently, the importance of management and cultivation of grasses has been increased in Korea. Among these cultural practices, the appropriate control of diseases is considered more important than other cultivation techniques such as fertilization and irrigation. The damages of brown patch and large patch caused by Rhizoctonia spp. and Pythium blight caused by Pythium spp. are serious in the major cultivation area of turfgrass in Korea. Since these diseases are difficult to control by agrochemicals, the damages are very serious if these are occured. The periodic spray of agrochemicals, to protect and control these diseases could make some problems of toxicity and environmental pollution as well as rising of non-target diseases. Therefore, the biological methods to control diseases have been required to decrease problems resulted from overuse of agrochemicals, to conserve natural ecosystem, and to control effectively diseases of grasses in the long period. The number of studies about biological control using antagonistic microorganisms have been increased for last half century. However, the application of biological control method has been very limited. In this study, thirteen isolates of R. cerealis, 8 isolates of R. solani and 3 isolates of Phthyn spp. have been isolated from diseased turfgrass in golf course and grass-culture area that have patch and wilting symptoms of zoysia grass and creeping bentgrass. Isolation frequency of R. cerealis and R. solani was high in especially zoysiagrass, while Pythym spp. was isolated from bent grass at low frequency but showed high pathogenicity. Totally, 205 isolates of soil microorganisms were isolated in this study as primary antagonistic microorganism by Herr's triple agar layer plate and dual culture method using rhizosphere of grasses, soil of crop field as the source of antagonistic microorganisms. Among the 205 isolates, 23 isolates were actinomycetes and 182 isolates were bacteria. All of the actinomycetes were isolated by Herr's method. Antagonistic effect of primary isolated microorganisms was tested for in vitro mycelial growth inhibition against pathogenic fungi isolated from grasses and for inhibition of disease occurrence in 24 well tissue culture plate and pot experiment. Then, four isolated of bacteria which are BG23, BG74, BG136 and BG171 were selected as antagonistic microorganisms against soil-born pathogenic fungi of bentgrass.

• The Plant Pathology Journal
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• v.24 no.1
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• pp.58-62
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• 2008

Utilization of carbon sources by Bacillus cereus D324, a biological control agent, and Pythium species, which causes rice seedling disease, was studied with the objective of increasing the efficacy of biological control by providing the biological control agent with specific beneficial carbon sources. D-galactose, D-sorbitol, and D-mannitol were poor carbon sources for Pythium spp. growth but were good for B. cereus D324 growth. Growth in a growth chamber of rice seeds coated with B. cereus D324 amended with specific carbon sources, such as D-galactose and D-sorbitol, showed significantly enhanced seedling emergence compared to seeds coated only with B. cereus D324. Field trials showed that both seedling emergence and yield increased, when the above specific carbon sources were added to B. cereus D324 in seed coating formulations. This result indicated that amending seed coating formulations with specific carbon sources could significantly increase seedling emergence and yield in the field.

• Journal of the Korean Society of Tobacco Science
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• v.13 no.1
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• pp.53-60
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• 1991

Seedling rot occurred on burley tobacco at the early growing stage after transplanting was surveyed in the Chonbuk province, the main area for burley tobacco production, during the 3 crop years from 1986. The incidence of disease was about 0.6-0.7% every year and major causal organisms were Pythium spp. More diseased plants were observed in the fields in which tobacco planted with improved mulching system than in that with any other mulching system. The temperature and relative humidity in the planting hole covered with polyethylene film for 11 days after transplanting were recorded by 27-45$^{\circ}C$ and 75~95%, respectively. The punched polyethylene film mulching field showed less diseased plants than that with improved mucking. In improved mulching system the longer period of mulching caused higher incidence of seedling rot(r=0.74**). Soil drench treatment of 200m1 of aqueous Metalaxyl Solution(125ppm) was effective to control the disease.

• Applied Biological Chemistry
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• v.46 no.2
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• pp.79-83
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• 2003

Elicitins, proteinaceous elicitors secreted from Oomycetes fungi (Phytophthora spp. and Pythium spp.), have been known as inducer of hypersensitive response (HR) in incompatible interactions between plant and pathogens. Five elicitins among many Korean Phytophthora species caused the reactions of distal HR in radish, chinese cabbage and some hot pepper cultivars, but not in cucumber and tomato. Because the isolation of elicitin from Phytophthora cambivora hasn't been reported yet, we have purified a cambivorein, a new member of the elicitin family, from the culture filtrate of Phytophtilora cambivora (KACC 40160) by using FPLC (Fast Protein Liquid Chromatography, AKTA) with sepharose S and Sephacryl HR columns. We confirmed that it induces necrosis activities in some hot pepper cultivars and its molecular weight is about 10 KDa by Tricine-SDS-PAGE. Comparison of amino acid sequences of its N-terminal ends also informed the identification of Iysine at the 13th position, which is characteristic of a kind of basic elicitin isoform $({\beta}-isoform)$. It Also showed that our elicitin is not identical with N-terminal sequences of many elicitins reported from Phytophthora spp..

• Asian Journal of Turfgrass Science
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• v.24 no.2
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• pp.117-124
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• 2010

Turfgrass survival and ocurrence of brown patch disease during summer season were investigated the forty six cultivars of cool season grasses in 6 species, popularly used in golf courses in Korea. Ocurrence of brown patch disease was evaluated two times in July. The percentage of turfgrass survival was investigated on Aug. 20 and on Sep. 20 in 2010. There were significant difference for the percentage of turfgrass survival and brown patch disease occurrence among cultivars. Brown patch disease caused by Rhizoctonia spp. and Pythium aphanidermatum with rDNA ITS were showed most susceptible in creeping bentgrass (Agrostis palustris Huds) cultivars and chewings fescue (Festuca rubra var. commutata Gaud) cultivars. The percentage of turfgrass survival during August to September was showed lower creeping bentgrass cultivars and chewings fescue cultivars than another cultivars. Among of 20 cultivars in Kentucky bluegrass (Poa pratensis L.) species were showed highest survival in cultivars of "Nuglade", "Cabernet", "Midnight II" and "Beyond". 6 cultivars of Tall fescue (Festuca arundinacea Schreb) were showed highest survival in cultivars of "Double sentry", "Inferno", and cultivars of "Accent II" in Perennial ryegrass (Lolium parenne L.) species.

• Asian Journal of Turfgrass Science
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• v.25 no.1
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• pp.48-51
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• 2011

This study was performed to functional improvement by fermenting of SCB (Slurry Composting and Biofiltering) liquid fertilizer. After screening of cellulose decomposing test using microorganisms originated from composts produced with turf grass clipping, five kinds of Cellulose Decomposing Microorganisms (CDMs) were selected. The optimum medium for CDMs culture was Tryptic soy broth. The optimum fermenting time of CDMs in SCB liquid fertilizer was 36 hour. In addition, CDMs showed antimicrobial activity in vitro. Sclerotinia homoeocarpa, Rhizoctonia solani AG2-2(IV) and Pythium spp. were inhibited by CDMs, but Rhizoctonia solani AG2-2(IIIB) in vitro uneffected by CDMs we isolated.

• Asian Journal of Turfgrass Science
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• v.20 no.1
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• pp.57-63
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• 2006

This study was carried out to investigate control efficacy of natural compound, TGR-N1 against turfgrass fungal diseases. TGR-N1 showed antimicrobial activity in vitro. Rhizoctonia solani AG 1-1, Rhizoctonia solani AG2-2, Rhizoctonia cerealis, Sclerotinia homoeocarpa and Colletotrichum graminicola were inhibited by 500 times and 1,000 times of diluents of TGR-N1. Pythium spp. was not inhibited by the same diluents of TGR-N1. The TGR-N1 also showed a remarkable antifungal activity against Rhizoctonia solani AG 1-1, Rhizoctonia solani AG2-2 in field. This study proved the antifungal activity of natural compound, TGR-N1 and showed its potential as a natural pesticide.

• The Plant Pathology Journal
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• v.15 no.5
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• pp.287-294
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• 1999

A technique based on the polymerase chain reaction (PCR) for the specific detection of genus Phytophthora and Phytophthora cryptogea-P. drechsleri complex group was developed using nucleotide sequence information of ribosomal DNA (rDNA) regions. The internal transcribed spacers (ITS) including 5.8S were sequenced for P. cryptogea-P. drechsleri complex group and its related species. Two pairs of oligonucleotide primers were designed. Primer pair ITS1/Phy amplified ca. 240 bp fragment in 12 out of 13 specie of Phytophthora, but not in Pythium spp., Fusarium spp.and Rhizoctonia solani. Primer pair rPhy/Pcd amplified 549 bp fragment only in P. cryptogea-P. drechsleri complex group, but not in other Phytophthora spp.and other genera. Specific PCR amplification using the primers was successful in detecting Phytophthora and P. cryptogea-P. drechsleri complex group in diseased plants.

• ALGAE
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• v.38 no.1
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• pp.71-80
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• 2023

The oomycete pathogens Pythium porphyrae, causing red rot disease, and Olpidiopsis spp. causing Olpidiopsis-blight, cause serious economic losses to Pyropia sea farms in Korea. During the washing step for Pyropia processing, these pathogens proliferate rapidly, significantly reducing the quality of the final product. To develop non-acidic treatments for these pathogens, various calcium salts were tested against the infectivity of P. porphyrae and Olpidiopsis pyropiae on Pyropia gametophytes, and calcium propionate was the most effective. When Pyropia blades were immersed in 10 mM calcium propionate for 1 h after inoculation with the oomycete pathogen, infection rate of both oomycete pathogens on day 2 was significantly lower (7.1%) than control (>95%). Brief incubation of Pyropia blades in calcium propionate also reduced the spread of infection. The infected area of Pyropia thallus was reduced to 14.3% of the control in 2 days after treatment with 100 mM calcium propionate for 30 s. In field experiments conducted in actual aquaculture farms, it has been shown that a brief 30 s wash every two weeks with 100 mM calcium propionate can effectively reduce the spread of oomycetes throughout the entire culture period. The above results suggest that calcium propionate can be a useful means for controlling the spread of oomycetes not only during laver processing but also during aquaculture.

• Horticultural Science & Technology
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• v.16 no.3
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• pp.347-349
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• 1998

Slow sand filtration was modified and applied for the determination of eliminating efficacy of various fungi and for recommending an easy approach to growers. After 1,500 liter filtration, Fusarium oxysporum was eliminated by several substrates such as activated charcoal (92.5% elimination), silica (90.8%), vermiculite (90.5%), sand (82.3%), perlite (50.4%), and hydroball (21.2%). Silica was able to eliminate several fungi by maximal ratio, which was corresponded to Fusarium oxysporum 120 cfu/mL. Collectotrichum lagenarium 98 cfu/mL. Phytophthora capsici 82 cfu/mL, Botrytis cinerea 62 cfu/mL, Pythium spp. 42 cfu/mL, and Sclerotinia ssp. 52 cfu/mL. In this case, the change of EC was minor and pH was maintained to about 7. In deep flow culture of 'Ddooksum Cheokchookmyeon' lettuce and 'Seokwang' tomato, silica-, activated charcoal-, and vermiculite-based filtration system successfully eliminated Fusarium oxysporum and Phytophthora capsici from the nutrient solution. As a result, these plants were not diseased by ten weeks after inoculation. With this system, growers can easily control the root-zone fungi in the recirculating hydroponic system.