• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.21-27
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• 1998

Methanol extracts from 25 leguminous seeds were tested for their fungicidal activities toward six phytopathogenic fungi, using whole plant test in a greenhouse. The efficacy varied with both the plant pathogen and legume species used. At 5 mg/pot, potent fungicidal activities were produced from extracts of Cassia obtusifolia, Glycine max var. solitae, G. max var. yagkong, G. max var. hooktae, Phaseolus multiflorus, P. radiatus var. aurea, and Vigna sinensis against Botrytis cinerea, Puccinia recondita, and Erysiphe graminis. These seed extracts were highly effective against three B. cinerea strains resistant to carbendazim, procymidone, and diethofencarb. All leguminous seed extracts revealed weak or no fungicidal effect against Rhizoctonia solani, Pyricularia grisea, and Phytophthora infestans. As a naturally occurring fungicide, leguminous seed-derived materials described could be useful as new fungicidal products against various plant diseases induced by phytopathogenic fungi.

• Korean Journal of Environmental Biology
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• v.20 no.2
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• pp.130-135
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• 2002

Species of Genus Trichoderma are commercially applied as biological control agents against fungal Pathogens. A powerful biocontrol agent, Trichoderma sp. SJG-99721 was isolated from 305 isolates by morphological characters, chitinase activities and antifungal activities against Phytophthora capsiei. The isolate was identified as Trichoderma harzianum from various features such as growth rate at $27^\circ{C}$, significant growth ratio of $27^\circ{C}$ to $17^\circ{C}$, amount of aerial mycelium, types of branching: system, and disposition patterns of phialide and phialospore. Trichoderma harzianum SJG-99721 have been shown to act as a powerful biological agent against fungal phytopathogens; Botrytis cinerea, Rhizoctonia solani, Phytophthora cryptogea, Phytophthora capsiei, Sclerotinia sclerotiorum, Mycoshaerella melonis, Alternaria sotani, Fusarium oxysporum, Collectotrichum gloesporioodes, Alternaria alternata, Phythium ultimum, Phytophthora drechsleri, Pyricularia grisea.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.396-403
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• 2014

Ginseng (Panax ginseng C. A. Meyer) is an economically valuable pharmaceutical crop in Korea. In order to find promising biocontrol agents for soil-borne fungal pathogens which infect ginseng roots, we have isolated actinomycete, BK185 from soil. The isolate was investigated for the antifungal activity against to ginseng rot pathogens prior to testing genetic and chemical properties. The strain was identified as Streptomyces sp. using phylogenetic analysis based on 16S rRNA gene sequence. The most closely related species was S. sporoclivatus and S. geldanamycininus with high similarities (>99%). The isolate, BK185 showed positive reaction for PCR detection targeting biosynthetic gene clusters of PKS (Type-I polyketide synthase) and NRPS (Non-ribosomal polypeptide synthetase) genes. Major metabolite from the BK185 was analyzed by The LC/MS and identified to geldamycin, which was known to contained broad antibacterial, antifungal or anticancer activities. The results provide evidences that the strain, BK185 can be promising biocontrol agent for ginseng organic farming.

• Journal of Microbiology and Biotechnology
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• v.31 no.9
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• pp.1231-1240
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• 2021

Members of the genus Bacillus are known to play an important role in promoting plant growth and protecting plants against phytopathogenic microorganisms. In this study, 21 isolates of Bacillus spp. were obtained from the root micro-ecosystem of Suaeda glauca. Analysis of the 16S rRNA genes indicated that the isolates belong to the species Bacillus amyloliquefaciens, Bacillus velezensis, Bacillus subtilis, Bacillus pumilus, Bacillus aryabhattai and Brevibacterium frigoritolerans. One of the interesting findings of this study is that the four strains B1, B5, B16 and B21 are dominant in rhizosphere soil. Based on gyrA, gyrB, and rpoB gene analyses, B1, B5, and B21 were identified as B. amyloliquefaciens and B16 was identified as B. velezensis. Estimation of antifungal activity showed that the isolate B1 had a significant inhibitory effect on Fusarium verticillioides, B5 and B16 on Colletotrichum capsici (syd.) Butl, and B21 on Rhizoctonia cerealis van der Hoeven. The four strains grew well in medium with 1-10% NaCl, a pH value of 5-8, and promoted the growth of Arabidopsis thaliana. Our results indicate that these strains may be promising agents for the biocontrol and promotion of plant growth and further study of the relevant bacteria will provide a useful reference for the development of microbial resources.

• Korean journal of applied entomology
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• v.26 no.4 s.73
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• pp.229-237
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• 1987

In order to study the biological control of soil-borne disease of sesame, antagonistic isolates of Trichoderma , Bacillus sand streptomyces to Fusarium oxysporum and Rhizoctonia solani were isolated from the rhizosphere soils of sesame plants and some other habitats. Out of the isolates of microorganisms collected a strain of Trichoderma viride was selected as a biological control agent for the study and its effect on the control of damping-off and the seedling growth of sesame was investigated. The results obtained are as follows: 26 percents of Bacillus spp. isolated from the rhizosphere soil of sesame plants showed antagonism to two pathogenic fungi. Important species were B. Subtilis and B. polymyxa. Streptomyces species isolated from the rhizosphere soils of sesame lysed the cell wall of hyphae and conidia of F. oxysporum and reduced conspicuously the formation of macroconidia and chlamydospores of the fungus. 84 percents of Trichoderma spp. isolated from the rhizosphere soil of sesame plants were antagonistic to F. oxysporum and 60 percents of the isolates were antagonistic to both F. oxysporum and R. solani. Trichoderma viride TV-192 selected from antagonistic isolates of Trichoderma spp. was highly antagonistic to F. oxysporum and soil treatment with the isolate reduced notably damping-off of sesame. T. viride TV-192 showed better growth in crushed rice straw, barley straw and sawdust media than F. oxysporum. Sawdust was selective for the growth of T. viride. Supplementation of wheat bran and mixtures of wheat bran and sawdust inoculated with T. viride TV-192 in the soil reduced remarkably damping-off of sesame by F. oxysporum but high density of the fungus TV-192 caused the inhibition of seed germination and seedling growth of sesame. Inhibitory effects of Trichoderma species on seed germination and seedling growth of sesame were different according to the isolates of the fungus. Normal sesame seedlings on the bed treated with the fungus showed better growth than not treated seedlings.

• The Korean Journal of Mycology
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• v.21 no.1
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• pp.16-22
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• 1993

Morphological and cultural characteristics of fungi causing rice sclerotial diseases were examined. Hyphal widths of R. solani and R. oryzae were same and ranged $6.0-12.0\;{\mu}m$ with average $9.0\;{\mu}m$, the widest among those of the sclerotial fungi examined. Hyphal width of R. oryzae sativae ranged $6.0-9.0{\mu}m$ with average $7.4{\mu}m$. Hyphal width of R. cerealis was the narrowest among those of Rhizoctonia species examined, and the same was hyphal width of S. oryzae among those of Sclerotium species. Nuclear staining by HCL-Giemsa method showed that R. solani and R. oryzae had many nuclei within one hyphal cell, S. oryzae one nucleus, and the other sclerotial fungi mostly two nuclei. The nuclear number of R. solani was the largest, which ranged 2-17 with average 6.3. Average size of sclerotia of the sclerotial fungi except S. hydrophilum and S. oryzae produced in lesions ranged 1.0-2.0mm. Average size of sclerotia of S. hydrophilum and S. oryzae was 0.5mm and 0.24mm, respectively. Sclerotia of R. solani and R. oryzae produced in culture were more variable in size and larger than those produced in lesions. However, the sclerotial sizes of the other sclerotial fungi produced in culture were almost the same as those produced in lesions. Sclerotial colors of sclerotial fungi produced in lesions were similar to those produced in culture, but sclerotial shapes of some sclerotial fungi exhibited somewhat difference between the sclerotia produced in lesions and in culture. Optimum temperature for mycelial growth of R. cerealis was $23^{\circ}C$, and that of the other sclerotial fungi ranged from $27\;to\;33^{\circ}C$. Maximum temperature for mycelial growth of some sclerotial fungi was as high as $41^{\circ}C$, while that of R. cerealis was as low as $31^{\circ}C$. Minimum temperature for mycelial growth of R. cerealis was $2^{\circ}C$, and that of the other sclerotial fungi ranged from $6\;to\;10^{\circ}C$.

• Research in Plant Disease
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• v.17 no.3
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• pp.280-287
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• 2011

This investigation was undertaken to survey toxigenic fungal contamination of various rice samples in 93 rice processing complexes (RPC) in Korea. Rice was grown in 2009 and the samples were collected in 2010. Seven types of rice samples such as unhusked, brown, blue-tinged, discolored, polished, half-crushed, and rice husks were obtained from each RPC. One-hundred and five grains of each sample were placed on PDA plates after surface disinfection. The incidence of fungal contaminants was 26.8%. Aspergillus spp. was the most dominant fungal contaminants and Fusarium spp. was the most frequently occurred in samples. The heaviest Fusarium contamination was found in unhusked grain, rice husks, and bare blue-tinged rice and followed by colored rice whereas broken rice was the least contaminated. Regional difference of fungal contamination was distinctive. Fusarium incidence in the rice samples from southern region of Korea including Jeolla and Gyeongsang Provinces was higher than those from central region including Chungcheong, Gyeonggi, and Gangwon Provinces. In contrast to Fusarium spp., Aspergillus spp. and Penicillium spp. were dominated in brown and polished rice samples and their incidences were more severe in central region than southern region. The major contaminants shown more than 1% of kernels infected were Aspergillus (5.0%), Fusarium (2.0%), Alternaria (1.4%), Dreschlera (1.3%), Penicillium spp. (1.3%), and Nigrospora spp. (1.0%). Collectotrichum, Pyricularia, Myrothecium, Epicoccum, Cladosporium, Moniliella, Gloeocercospora, Chaeto- mium, Curvularia, Phialopora, Acremonium, Gliomastix, Trichoderma, Rhizopus, Phomopsis, Paecilomyces, Genicularia, Geotrichum, Acremoniella, Rhizoctonia, Phoma, Oidiodendran, and Candida spp. were among the rest observed at low incidence. The major contaminants of rice samples were well-known as toxigenic fungal genera so toxin producibility of these fungal isolates is necessary to be examined in future. It is also needed to study Myrothecium spp. on species level as it was detected for the first time in rice.

• The Korean Journal of Pesticide Science
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• v.19 no.1
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• pp.71-79
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• 2015

In order to investigating the effects of antifungal activity of intestinal bacteria obtained from insect, it was identified these bacteria isolated from the gut. In this result, total 49 isolates of intestinal bacteria were identified from 10 kinds of insect species. It was that 4 isolates including Cedecea sp. from Nesidiocoris tenuis, 3 isolates including Enterobacter sp. from Odontotaenius disjunctus, 4 isolates including Acinetobacter sp. from Reticulitermes speratus, 4 isolates including Clavibacter sp. from Riptortus clavatus, 11 isolates including Bacillus sp. from Lema decempunctata, 3 isolates including Enterococcus sp. from Henosepilachna vigintioctopunctata 2 isolates including Staphylococccus sp. from Harmonia axyridis, 5 isolates including Enterobacter asburiae from Popillia mutans, 7 isolates including Aeromonas sp. from Hydrophilus acuminatus, and 7 isolates including Brucella sp. from Anomala octiescostata. In order to investigating antifungal activity against plant-pathogenic fungi, Altanaria solani, Colletotrichum gloeosporioides, Botrytis cinerea, Fusarium oxysporum, Phytophthora capsici, Rhizoctonia solani and Selerotinia sclerotiorum were dual cultured with each 49 gut enterobacteriaceae. As these results showed that many isolates have the antifungal activities including 26 isolates against A. solani, 6 isolates against B. cinerea, 13 isolates against C. gloeosporioides, 11 isolates against F. oxysporum, 17 isolates P. capsici, 2 isolates against R. solani and 2 isolates against S. sclerotiorum. Pseudomonas aeruginosa was showed strong antifungal activity against all of tested plant pathogens. It might be taken a potential for application against plant-pathogenic fungi with useful control agent.

• Research in Plant Disease
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• v.21 no.2
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• pp.58-66
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• 2015

This study was conducted to evaluate control efficacy of a fermented food 'Cheonggukjang' against cucumber powdery mildew caused by Sphaerotheca fuliginea in greenhouse. Sterilized Daepung beans were inoculated with the rice straw as natural inoculum and then incubated for 72 hrs at $42^{\circ}C$ in the household cheonggkjang maker. After 72 hrs of cheonggukjang fermentation, white zymogens were grown on the surface of a sterile Daepung beans. The pH of the 72 hrs fermented soybean was not significantly changed and electrical conductivity was found to increase by about 2 times than before fermentation. The population density of soybean zymogen showed a peak of growth at 60 hrs after fermentation and the concentration of zymogen was $8.2{\times}10^7cfu/ml$. Soybean zymogen form of the colony was divided into three kinds of bacteria and a white and a large colony (WL) was predominant bacteria among those up to 60 hrs of fermentation. To control the cucumber powdery mildew, diluted solutions of cheonggukjang was applied from 6.0% to 30.0% on cucumber leaves and they showed injury symptoms on cucumber leaves in more than 15% of them. However, more than 6.0% diluted cheonggukjang solutions showed more than 77.8% control effect of cucumber powdery mildew at 15 days after treatment. The fermented bacteria of Chenggukjang were well established in the cucumber leaf area at 15 days after treatment. The antifungal activity of 10% diluted cheonggukjang solutions was excellent for four species of plant fungal pathogens, Colletotrichum gloeosporioides, Sclerotinia cepivorum, Rhizoctonia sloani and Phytophthora capsici in the dual culture test. Results indicated that foliar application of Cheonggukjang solution could be used for the control of powdery mildews occurring on organically cultivated cucumber.