• 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 Korean Journal of Pesticide Science
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• v.16 no.4
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• pp.383-386
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• 2012

Streptomyces spp. were isolated from rhizosphere in fallow lands. The Streptomyces spp. were identified as Streptomyces griseus (MSS181), Streptomyces griseoaurantiacus (MSS269), Streptomyces microflavus (MSS275), Streptomyces herbaricolor (MSS276) based on 16S rRNA gene sequences. Afterwards, cucumber, pepper, tobacco and tomato were drenched with the isolates at early growth stages and plant growth such as height and dry weight of plants was measured. By treatment of Streptomyce spp., plant height of cucumber was increased by 16-29% compared to the control, But there were no statistically significant differences in dry weight. When the same isolates were treated on chili-pepper, plant height and dry weight of chili-pepper were increased respectively by 10-19% and 19-25% compared to the control. The dry weight of tobacco and tomato were increased by 44-73% and 65-165%, respectively compared to the control. When antifungal activities of the isolates were tested against plant pathogenic fungi, Streptomyces microflavus (MSS275) effectively inhibited the mycelial growth of Phytophthora capsici, Fusarium oxysporum, Rhizoctonia solani and Sclerotinia sclerotiorum.

• Journal of Life Science
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• v.12 no.2
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• pp.200-207
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• 2002

This study was carried out to isolate of antagonistic bacterium against Pythium ultimum and Rhizoctonia solani AG-4, causal pathogens of vegetables damping-off. Total of 600 strains were isolated from soil and plait roots. The isolates were screened for antagonism against Pythium ultimum and Rhizoctonia solani AG-4. One strain, named YJ-37, was sellected for detained study among those microoganisms screened. It was identified as Bacillus ehimensis based on morphological and physiological characterisitics according to the Bergey's mannual of systematic bacteriology, Sherlock system of Microbial ID Inc. and 16S rDNA sequences methods. Furthermore Bacillus ehimensis YJ-37 showed antifungal activities against Alternaria altrata, Collectotrichum gloeosporioides, Didymella bryoniae, Fusarium moniliforme, Fusarium oxysporum, F. oxysporum cucumerinum, F. oxysporum niveum, Gloeosporium sp., Glomerella sp., G. cingulata, G. lagenaria, Penicillium digitatum, P. italicum, Phytophthora capsici, Sclerotinia sclerotiorum, and Stemprhylium solani.

• The Plant Pathology Journal
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• v.28 no.2
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• pp.185-190
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• 2012

Sclerotinia sclerotiorum is a serious pathogen which causes yield loss in many dicotyledonous crops including potato. The objective of this study was to assess the potential of biofumigation using three Brassica crops including Brassica napus, B. juncea and B. campestris against potato stem rot caused by S. sclerotiorum by in vitro tests. Both macerated and irradiated dried tissues were able to reduce radial growth and sclerotia formation of five pathogen isolates on PDA, but macerated live tissues were more effective. Compared with other tested crops, B. juncea showed more inhibitory effect against the pathogen. The volatile compounds produced from macerated tissues were identified using a gas chromatograph-mass spectrometer. The main identified compounds were methyl, allyl and butyl isothiocyanates. Different concentrations of these compounds inhibited mycelial growth of the pathogen in vitro when applied as the vapor of pure chemicals. A negative relationship was observed between chemicals concentrations and growth inhibition percentage. In this study, it became clear that the tissues of local Brassica crops release glucosinolates and have a good potential to be used against the pathogen in field examinations.

• Asian Journal of Turfgrass Science
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• v.20 no.2
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• pp.191-201
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• 2006

Dollar spot caused by Sclerotinia homeocarpa is one of major diseases in putting greens. Microorganisms antagonistic to S. homeocarpa, a pathogen of dollar spot, were primarily screened through in vitro tests, including dual culture method and triple layer agar diffusion method. In vivo tests were also conducted to select the best candidate for a biocontrol microorganism, using pot experiment. Bacillus subtilis EW42-1 and Trichoderma harziaum GBF-0208 were finally selected as biocontrol agents against dollar spot. Relative Performance Index(RPI) was used as a criterion of selecting potential biocontrol agents. B. subtilis EW42-1 and T. harzianum GBF-0208 showed resistance to several agrochemicals mainly used in a golf course. B. subtilis EW42-1 and T. harzianum GBF-0208 suppressed effectively the disease progress of dollar spot like synthetic fungicide tebuconazole in the nursery where dollar spot had seriously occurred. B. subtilis EW42-1 and T. harzianum GBF-0208 have a potential to be biocontrol agents for the control of dollar spot.

• Asian Journal of Turfgrass Science
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• v.23 no.2
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• pp.209-218
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• 2009

Bacterial isolates collected from rhizosphere of turfgrass showed strong in vitro antagonistic activities against a number of turfgrass soilborne pathogens such as Rhizoctonia cerealis, R. solani AG-1(1B), Sclerotinia homoeocarpa and Typhula incarnata. In vivo study, four bacterial isolates selected have control values over 60% against one or more turfgrass pathogenic fungi. The antagonistic effects of the bacterial isolates varied depending on fungal species, host plant, and disease pressure, indicating that control effects of the antagonists could be variable depending on field conditions. They were classified as belonging to the genus Pseudomonas species, based on morphological and biochemical characteristics as well as 16S rRNA analysis. The four bacterial isolates are under a study for finding proper cultural conditions and determination formulation type.

• The Plant Pathology Journal
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• v.37 no.4
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• pp.365-374
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• 2021

White rot or stem rot caused by Sclerotinia sclerotiorum is one of the most destructive fungal diseases that have become a serious threat to the successful cultivation of oilseed Brassicas. The study was designed with an aim to investigate the association between the pathogenic aggressiveness and pathogenicity determinants of this pathogen specifically in Brassica for the first time. For this, a total of 58 isolates of S. sclerotiorum from different geographical regions were collected and purified. These isolates were inoculated on a Brassica juncea cv. RL-1359 and they exhibited high level of variation in their disease progression. The isolates were grouped and then 24 isolates were selected for the biochemical analysis of pathogenicity determinants. The isolates varied significantly with respect to their total organic acids, oxalic acid production and pectin methyl esterase and polygalacturonase activity. The oxalic acid production corresponded to the disease progression of the isolates; the isolates with higher oxalic acid production were the more aggressive ones and vice-versa. This is, in our knowledge, the first study to establish a correlation between oxalic acid production and pathogenic aggressiveness of S. sclerotiorum on B. juncea. However, the pectinases' enzyme activity did not follow the trend as of disease progression. These suggest an indispensable role of oxalic acid in pathogenicity of the fungus and the potential to be used as biochemical marker for preliminary assessment of pathogenic aggressiveness of various isolates before incorporating them in a breeding program.

• The Plant Pathology Journal
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• v.39 no.1
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• pp.39-51
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• 2023

Common bean (Phaseolus vulgaris L.) is one of the most important crops in human food production. The occurrence of diseases, such as white mold, caused by Sclerotinia sclerotiorum can limit the production of this legume. The use of Trichoderma has become an important strategy in the suppression of this disease. The aim of the present study was to evaluate the effect of volatile organic compounds (VOCs) emitted by Trichoderma azevedoi CEN1241 in five different growth periods on the severity of white mold in common bean. The in vitro assays were carried out in double-plate and split-plate, and the in vivo assays, through the exposure of the mycelia of S. sclerotiorum to the VOCs of T. azevedoi CEN1241 and subsequent inoculation in bean plants. Chemical analysis by gas chromatography coupled to mass spectrometry detected 37 VOCs produced by T. azevedoi CEN1241, covering six major chemical classes. The profile of VOCs produced by T. azevedoi CEN1241 varied according to colony age and was shown to be related to the ability of the biocontrol agent to suppress S. sclerotiorum. T. azevedoi CEN1241 VOCs reduced the size of S. sclerotiorum lesions on bean fragments in vitro and reduced disease severity in a greenhouse. This study demonstrated in a more applied way that the mechanism of antibiosis through the production of volatile compounds exerted by Trichoderma can complement other mechanisms, such as parasitism and competition, thus contributing to a better efficiency in the control of white mold in bean plants.

• Research in Plant Disease
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• v.30 no.2
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• pp.114-123
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• 2024

In July 2022, stem rot symptom was found in a peony plant grown in a pot under a greenhouse at Jinju, Gyeongnam Province, South Korea. Two fungal species were isolated from the infected peony stems and cultured on 1/2-strength potato dextrose agar for identification. The morphological characteristics of the fungal isolates were examined, and nucleotide sequences of the internal transcribed spacer region, β-tubulin and translation elongation factor 1-α were analysed. The pathogenicity of the two isolates was confirmed in detached peony leaves, according to Koch's postulates. To our knowledge, this is the report of Neopestalotiopsis clavispora and Sclerotinia sclerotiorum as the causal agents of peony stem rots. Antifungal activity of chemical fungicide propineb and rhizobacterium Bacillus siamensis H30-3 was shown against the two plant pathogenic fungi N. clavispora and S. sclerotiorum.Unidentified diffusible and volatile compounds from B. siamensis H30-3 could suppress in vitro mycelial growths of N. clavispora JJ 8-2-1 and S. sclerotiorum JJ 8-2-2.

• Korean Journal of Organic Agriculture
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• v.24 no.3
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• pp.465-484
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• 2016

This study evaluated the antifungal activity of varying concentrations of water-soluble extracts from native plants (Vitex rotundifolia, Tetragonia tetragonoides, Artemisia capillaris, Hibiscus hamabo and Ficus carica) against Stemphylium vesicarium, Penicillium italicum, Sclerotinia sclerotiorum, Pythium ultimum, Botrytis cinerea, Rhizoctonia solani and Colletotrichum gloeosporioides. Mycelium growth of pathogenic bacteria generally decreased in a concentration-dependent manner following treatment with the water extracts from donor plants. Closer analyses indicate varying inhibitory capacities depending on the type of donor plant and pathogenic bacteria. Specifically, mycelium growth of S. vesicarium varied depending on the concentration of the water extracts from T. tetragonoides (r = -0.857, p<0.01) and A. capillarys (r = -0.868, p<0.01). Also, P. italicum and V. rotundifolia (r = -0.833, p<0.01), S. sclerotiorum and V. rotundifolia (r = -0.862, p<0.01), A. capillaris (r = -0.902, p<0.01), B. cinerea and T. tetragonoides (r = -0.896, p<0.01) showed an inverse relationship. The rate of mycelial growth inhibition of pathogenic bacteria analysed are as follows: P. ultimum 94%, B. cinerea 50%, C. gloeosporioides 80% in 100% treatment of T. teragonoides. A. capillaris inhibited S. vesicarium by 43%, P. ultimum by 90%; H. hamabo inhibited P. italicum by 50%, S. sclerotiorum by 26%, and F. carica inhibited R. solani by 74%. Total phenol content with antifungal activities are as follows: A. capillaris 16.15 mg/g, F. carica 7.81 mg/g, V. rotundifolia 6.18 mg/g, H. hamabo 5.25 mg/g, T. tetragonoides 4.41 mg/g, and total flavonoid content is as follows: A. capillaris 27.57 mg/g, V. rotundifolia 12.49 mg/g, F. carica 11.45 mg/g, H. hamabo 5.77 mg/g, T. tetragonoides 5.08 mg/g.