• Korean Journal Plant Pathology
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• v.14 no.4
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• pp.339-344
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• 1998

Since the leaf inoculation procedures are time-consuming and require considerable growth chamber space, a rapid dioassay method for screening of pathogenicity of Didymella bryoniae, a casual agent of gummy stem blight in watermelon, was established in this paper. The method produced reliable results within 8 days ( 5 days for growing seedlings and 3 days for rapid disease response in the seedlings). After contaminants in the root of 4~5 day-old seedlings had been washed using sterilized water, 5 seedlings were dipped into a vial containing 12 ml of conidial suspension (106 cells/ml). After the vials were placed in a growth chamber (22$^{\circ}C$, RH 50%, 14hr light/10hr darkness) for 3 days, susceptibility and resistance of cultivars were determined by the degree of disease response on cotyledon. The result of obtained by the dip-inoculation method was well coincided with the results by the leaf inoculation procedures and the result that had been observed for several years in the field. Screening of collected watermelon cultivars by the dip-inoculation method revealed that all the 21 domestic cultivars collected were susceptible and only 3 foreign cultivars (PI 189225, PI 482322 and IT 188207) were resistant among 18 cultivars A cucumber cultivar (Marketer) and bitter cucumber were proven to be resistant against the D. bryoniae among 8 other different cucurbits tested. The SDS-PAGE patterns of total proteins from a susceptible (Keumcheon) and a resistant (PI 189225) watermelon cultivars were compared 0, 12, 24 and 36 hrs after inoculation. The amounts of two distinct protein bands (24 kDa and 70 kDa) were gradually increased after inoculation in both cultivars.

• Research in Plant Disease
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• v.24 no.1
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• pp.81-85
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• 2018

Chinese artichoke (Stachys sieboldii Miq.) belongs to herbaceous perennial plants of Labiatea and is cultivated as edible and medicinal crops in China, Japan and Korea. A Chinese artichoke plant showing virus-like symptoms was collected in Chungju, Korea. Plant sap of the sample was inoculated in Nicotiana tabacum cv. Xanthi-nc, Chenopodium quinoa and Chenopodium amaranticolor. Necrotic local lesions were observed in the inoculated leaves of N. tabacum cv. Xanthi-nc and C. amaranticolor, C. quinoa with systemic chlorotic spots and mosaic symptoms on the upper leaves. The disease reactions on indicator plants suggested that the collected Chinese artichoke sample was mixed-infected with different viruses. We detected three viruses by RT-PCR analysis using genus- and species-specific primer sets for Alfalfa mosaic virus (AMV), Cucumber mosaic virus (CMV) and Tobacco mosaic virus (TMV). This study is the first report of a mixed infection of three viruses in Chinese artichoke in Korea.

• Mycobiology
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• v.30 no.1
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• pp.51-54
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• 2002

This paper deals with the study on comparative efficacy and in vitro activity of cow urine and cow dung for controlling root rot disease of cucumber caused by Fusarium solani f. sp. cucurbitae Snyder & Hansen following slide germination and mycelial growth inhibition tests. Results showed that both germination of conidia and the percentage inhibition of mycelial growth decreased or suppressed and varied greatly with respect to different hour and days of incubation and kind of bio-matters. In between two bio-matters cow urine was found more effective than that of cow dung in conidial germination. No germination of conidia was recorded after one hour of incubation in any medium whereas in cow urine germination of conidia was not also observed even after 2 hours of incubation. After 7 hours of incubation out of 200 conidia of F. solani f. sp. cucurbitae, 28 in cow urine and 64 in cow dung were germinated while in control a total germinated conidia was 185. In case of percentage inhibition of conidial germination the highest percentage(100%) was recorded in cow urine after 2 hours of incubation followed by 3 hours(96.0%), 4 hours(91.0%) and 6 hours(89.4%). During the test on inhibition of mycelial growth, the highest percentage(62.8%) was recorded in cow urine potato dextrose agar(CUPDA) medium tested after 4 days of incubation, followed by 3 days(60.5%), 5 days(56.5%) and 2 days(55.0%). In this test cow dung potato dextrose agar(CDPDA) had less efficacy in suppression of the percentage inhibition of mycelial growth.

• Journal of Microbiology and Biotechnology
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• v.17 no.2
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• pp.280-286
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• 2007

We evaluated a commercial biopreparation of plant growth-promoting rhizobacteria (PGPR) strains Bacillus subtilis GB03 and B. amyloliquefaciens IN937a formulated with the carrier chitosan (Bio Yield) for its capacity to elicit growth promotion and induced systemic resistance against infection by Cucumber Mosaic Virus (CMV) and Pseudomonas syringae pv. tomato DC3000 in Arabidopsis thaliana. The biopreparation promoted plant growth of Arabidopsis hormonal mutants, which included auxin, gibberellic acid, ethylene, jasmonate, salicylic acid, and brassinosteroid insensitive lines as well as each wild-type. The biopreparation protected plants against CMV based on disease severity in wild-type plants. However, virus titre was not lower in control plants and those treated with biopreparation, suggesting that the biopreparation induced tolerance rather than resistance against CMV. Interestingly, the biopreparation induced resistance against CMV in NahG plants, as evidenced by both reduced disease severity and virus titer. The biopreparation also elicited induced resistance against P. syringae pv. tomato in the wild-type but not in NahG transgenic plants, which degrade endogenous salicylic acid, indicating the involvement of salicylic acid signaling. Our results indicate that some PGPR strains can elicit plant growth promotion by mechanisms that are different from known hormonal signaling pathways. In addition, the mechanism for elicitation of induced resistance by PGPR may be pathogen-dependent. Collectively, the two-Bacilli strain mixture can be utilized as a biological inoculant for both protection of plant against bacterial and viral pathogens and enhancement of plant growth.

• Korean Journal of Agricultural Science
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• v.49 no.1
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• pp.121-128
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• 2022

Fusarium wilt disease caused by Fusarium species is a major problem affecting cultivated cucurbit plants worldwide. Fusarium species are well-known soil-borne pathogenic fungi that cause Fusarium wilt disease in several cucurbit plants. In this study, we aimed to identify and classify pathogenic Fusarium species from cultivated Korean cucurbit plants, specifically watermelon and cucumber. Thirty-six Fusarium isolates from different regions of Korea were obtained from the National Institute of Horticulture and Herbal Science Germplasm collection. Each isolate was morphologically and molecularly identified using an internal transcribed spacer of ribosomal DNA, elongation factor-1α, and the beta-tubulin gene marker sequence. Fusarium species that infect the cucurbit plant family could be divided into three groups: Fusarium oxysporum (F. oxysporum), Fusarium solani (F. solani), and Fusarium equiseti (F. equieti). Among the 36 isolates examined, six were non-pathogenic (F. equiseti: 15-127, F. oxysporum: 14-129, 17-557, 17-559, 18-369, F. solani: 12-155), whereas 30 isolates were pathogenic. Five of the F. solani isolates (11-117, 14-130, 17-554, 17-555, 17-556) were found to be highly pathogenic to both watermelon and cucumber plants, posing a great threat to cucurbit production in Korea. The identification of several isolates of F. equiseti and F. oxysporum, which are both highly pathogenic to bottle gourd, may indicate waning resistance to Fusarium species infection.

• Journal of the Korean Society of Tobacco Science
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• v.33 no.1
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• pp.1-7
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• 2011

Major diseases of tobacco plants were surveyed throughout the Korea in 2011. Mosaic, bacterial wilt and hallow stalk were most severe during the harvest season on not only flue-cured tobacco plants but also burley tobacco plants. On flue-cured tobacco plants, mosaic caused by potato virus Y were more severe than those by tobacco mosaic virus or cucumber mosaic virus. The mosaic caused by potato virus Y was severe at Yeongwol and Chungju. On burley tobacco plants, mosaic were more severe at Jeongeup and Gochang than those at Chungnam and Jeonnam. A negative correlation between the mosaic incidence and the precipitation was recognized. On the other hand, there was a positive correlation between the incidence of hallow stalk incidence of flue-cured tobacco plants in harvesting stage and the precipitation during June was recognized significantly.

• The Plant Pathology Journal
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• v.25 no.4
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• pp.328-332
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• 2009

Diseases caused by Pepper yellow leaf curl virus infection is considered to be emerging plant diseases in Indonesia in the last five years. One key factor for disease management is the availability of accurate detection of the virus in plants. Polyclonal antibody for Pepper yellow leaf curl Indonesia virus-Bogor (PYLCIV-Bgr) was produced for detection of the virus using I-ELISA and DIBA methods. The antibody was able to detect PYLCIV-Bgr from infected plants up to dilution 1/16,384 and cross reaction was not observed with Cucumber mosaic virus (CMV), Tobacco mosaic virus (TMV), and Chilli veinal mottle virus (ChiVMV). Positive reaction was readily detected in membrane containing Begomovirus samples from Yogyakarta (Kaliurang and Kulonprogo) and West Java (Bogor and Segunung). Infection of PYLCIV-Bgr in chillipepper, tomato, and Ageratum conyzoides was also confirmed using polyclonal antibody for PYLCIV-Bgr in DIBA. Polyclonal antibody for PYLCIV-Bgr is suggested to be included in disease management approach due to its good detection level.

• Journal of Wetlands Research
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• v.9 no.1
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• pp.91-98
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• 2007

Antifungal activity of compost teas was evaluated in vitro and in vivo experiments. In vitro test, fourteen compost teas were produced using five different composts and through six different methods for compost tea production. Eleven pathogenic fungi were used as indicators of antifungal activity of compost teas. In vivo test, one of the compost teas used in vitro test was sprayed to cucumber leaves which were infected with powdery mildew in order to evaluate antifungal activity of compost tea. From the results of the tests, it was found that all compost teas used this study showed antifungal activity and the proper application of compost teas against pathogenic fungi for obtaining optimal effects was important to know.

• 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.

• Research in Plant Disease
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• v.23 no.1
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• pp.42-48
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• 2017

Chlorella is one of the microorganisms which can live autotrophically by their own photosynthesis. It was previously revealed that pre-treatment of Chlorella fusca caused a suppression of appressorium formation on the cucumber leaves after inoculation with Colletothrichum orbiculare. In this study, the ultrastructures of C. orbiculare on the cucumber leaves pretreated with C. fusca were observed using both scanning electron microscope (SEM) and transmission electron microscope (TEM). The SEM images revealed that most fungal conidia and hyphae were attached with lots of C. fusca cells. Also, the conidia could germinate but not form appressorium, which is necessary to penetrate into host tissue. These observations suggested that C. fusca adjoined to the fungus may play a role in suppression of the appressorium formation. On the other hand, the observations of TEM showed no remarkable cytological differences on the ultrastructures of the intracellular hyphae between in the pre-treated and untreated leaves. It seemed that the fungus could grow in the pre-treated plant tissues as in the untreated one. Based on these observations, it is suggested that the suppression of appressorium on the leaf surfaces by the C. fusca cells may be a main cause of the reduction of the anthracnose disease.