• Mycobiology
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• v.38 no.4
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• pp.286-294
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• 2010

Epicoccum purpurascens stain 5615 AUMC was investigated for its biocontrol activity against root rot disease caused by Pythium irregulare. E. purpurascens greenhouse pathogenicity tests using three leguminous plants indicated that the fungus was nonpathogenic under the test conditions. The germination rate of the three species of legume seeds treated with a E. purpurascens homogenate increased significantly compared with the seeds infested with P. irregulare. No root rot symptoms were observed on seeds treated with E. purpurascens, and seedlings appeared more vigorous when compared with the non-treated control. A significant increase in seedling growth parameters (seedling length and fresh and dry weights) was observed in seedlings treated with E. purpurascens compared to pathogen-treated seedlings. Pre-treating the seeds with the bioagent fungus was more efficient for protecting seeds against the root rot disease caused by P. irregulare than waiting for disease dispersal before intervention. To determine whether E. purpurascens produced known anti-fungal compounds, an acetone extract of the fungus was analyzed by gas chromatography mass spectrometry. The extract revealed a high percentage of the cinnamic acid derivative (trimethylsiloxy) cinnamic acid methyl ester. The E. purpurascens isolate grew more rapidly than the P. irregulare pathogen in a dual culture on potato dextrose agar nutrient medium, although the two fungi grew similarly when cultured separately. This result may indicate antagonism via antibiosis or competition.

• Journal of the Korean Wood Science and Technology
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• v.20 no.3
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• pp.55-60
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• 1992

Japanese red pine (Pinus densiflora S. et. Z.) decayed by brown-rot fungi Tyromyces palustris and Gloeophyllum trabeum were subjected to X-ray diffraction analysis and infrared spectral examinations. Pine woods decayed by T. palustris showed the increase of relative crystallinity in the initial stage of degradation. When the weight loss was above 30%, then the crystallinity went down slowly. In contrast, the wood samples degraded by G. trabeum showed the decrease of crystallinity from the beginning stage of decay. The changes of crystallinity in brown-rotted woods suggested that the degradation rate of crystalline cellulose was varied with the brown rot fungal species. X-ray diffraction analyses also indicated that crystalline cellulose was much more slowly broken down than the amorphous one. The most notable difference in the IR spectra of the brown-rotted wood samples was that the adsorption band centered at 1,730$cm^{-1}$ was significantly diminished in the decayed wood. indicating the degradation of hemicellulose by brown-rot fungi. However, no marked changes of intensities at 1,000, 1,060 and 1,040$cm^{-1}$ were observed in the brown rotted wood samples, suggesting that crystal line cellulose was resistant against the attack by brown rot fungi.

• Korean Journal Plant Pathology
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• v.11 no.2
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• pp.116-119
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• 1995

Occurrence of soft rots was observed on chicory that was massively grown in-In-jae, Kangwon-Do, Korea. At first, a creamy lesion was appeared on the chicory root, which was enlarged slowly in diameter and in depth. The affected root area became soft and mushy. This eventually resulted in wilting and death of the aboveground parts of the chicory. The causal organism isolated from the lesions was identified as Erwinia carotovora subsp. carotovora based on the physiological and chemical characteristics, and on the results of the Biolog Program (Biolog Inc. U.S.A.). Since E. carotovora subsp. carotovora is the first described bacterium that causes soft rot on chicory in Korea, we proposr to name the chicory disease caused by E. carotovora subsp. carotovora as "bacterial soft rot of chicory".

• The Plant Pathology Journal
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• v.24 no.1
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• pp.90-92
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• 2008

In 2007, a bulb rot of Allium victorialis var. platyphyllum Makino caused by Sclerotium rolfsii occurred sporadically in a herb farm at Gyeongsangnam-do, Korea. The symptom initiated with water-soaking lesion and progressed into bulb rot and wilt of a whole plant. Severely infected plants were blighted and killed eventually. White mycelial mats appeared on the lesion at early stage and a number of sclerotia were formed on the bulb. The sclerotia were spherical, $1{\sim}3 mm$ and white to brown. The optimum temperature for the growth and sclerotia formation was $30^{\circ}C$ on PDA. The hyphal width was measured $4-9{\mu}m$. The typical clamp connections were observed on PDA. Based on the symptom, mycological characteristics and pathogenicity to the host plant, this fungus was identified as Sclerotium rolfsii Saccardo. This is the first report on the bulb rot of A. victorialis var. platyphyllum caused by S. rolfsii in Korea.

• The Plant Pathology Journal
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• v.34 no.3
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• pp.218-235
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• 2018

Plant growth promoting rhizobacteria and endophytic bacteria were isolated from different varieties of turmeric (Curcuma longa L.) from South India. Totally 50 strains representing, 30 PGPR and 20 endophytic bacteria were identified based on biochemical assays and 16S rDNA sequence analysis. The isolates were screened for antagonistic activity against Pythium aphanidermatum (Edson) Fitzp., and Rhizoctonia solani Kuhn., causing rhizome rot and leaf blight diseases in turmeric, by dual culture and liquid culture assays. Results revealed that only five isolates of PGPR and four endophytic bacteria showed more than 70% suppression of test pathogens in both assays. The SEM studies of interaction zone showed significant ultrastructural changes of the hyphae like shriveling, breakage and desication of the pathogens by PGPR B. cereus (RBacDOB-S24) and endophyte P. aeruginosa (BacDOB-E19). Selected isolates showed multiple Plant growth promoting traits. The rhizome bacterization followed by soil application of B. cereus (RBacDOB-S24) showed lowest Percent Disease Incidence (PDI) of rhizome rot and leaf blight, 16.4% and 15.5% respectively. Similarly, P. aeruginosa (BacDOB-E19) recorded PDI of rhizome rot (17.5%) and leaf blight (17.7%). The treatment of these promising isolates exhibited significant increase in plant height and fresh rhizome yield/plant in comparison with untreated control under greenhouse condition. Thereby, these isolates can be exploited as a potential biocontrol agent for suppressing rhizome rot and leaf blight diseases in turmeric.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.2
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• pp.113-119
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• 2003

Soybean sprout pathogenic bacteria were isolated from the large, deep containers of a commercial factory. Over a period of one year, 40 pathogenic-like bacteria were isolated among a total of 732 isolates. In addition to bacteria previously reported to be associated with rotting, such as Pseudomonas putida and Erwinia carotovora, several other genera were also identified: Acinetobacter spp., Chryseobacterium spp., Klebsiella sp., Pantoea agglomerans, Bacillus sp. Fatty acid methyl ester (FAME) analysis using the Microbial ID (MIDI) system, and 16s rRNA sequence analysis, yielded identical results, confirming the identities of these microorganisms. Several types of selective media were not good for identification and determination of population structure in commercial environments, as colony type was not specific to the genus. There was no dominant bacterium, and we were not able to find the main bacterium responsible for soybean spout rot. Even though we did not identify a major target for controlling rot or screening for resistant cultivars, the results of this study indicated that bacterial rot of soybean sprout is endemic. In addition, it emerged that factory epidemics in summer are not caused by the bacteria isolated in this study.

• Research in Plant Disease
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• v.10 no.1
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• pp.82-85
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• 2004

Bacterial soft rot by Erwinia carotovora subsp. carotovora is one of the diseases causing the biggest damages in Chinese cabbage cultivation. This study was conducted to evaluate on suppressive effect of calcium fertilizer to bacterial soft rot of Chinese cabbage. Seven calcium fertilizers were selected for evaluation. And screening was conducted to select effective agents for controlling bacterial soft rot. When applied by the nursery test condition using mineral oil inoculation method with Chinese cabbage, calcium hydroxide had more suppressive efficacy than any other calcium fertilizer, While nitrogen fertilizer was induced the disease, calcium hydroxide was suppressed soft rot disease in field test as well as seedling test. Treatment of calcium+nitrogen fertilizer as well as calcium only showed a significant control effect in the field experiment with Chinese cabbage 'Sanchon' in 2003.

• The Plant Pathology Journal
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• v.19 no.5
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• pp.227-230
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• 2003

Ripe rot was commonly found in overripe kiwifruits (Actinidia deliciosa) during a disease survey conducted in Jeju and Jeonnam provinces in Korea in 1999. While the disease did not manifest any clear external symptoms on kiwifruits, it caused portion of the fruit surface to collapse. Watersoaked flesh tissue could be seen on the sunken part when the skin of the collapsed portion was peeled off. The milky internal symptom with dark green margin developed concentrically as the fruit ripened. A species of Botryosphaeria was consistently isolated from lesions showing typical symptoms of ripe rot on kiwifruit, and its pathogenicity was confirmed by artificial inoculation test on healthy kiwifruits. The fungus was also pathogenic to apple and pear. The mycological characteristics of the fungus were consistent with those of Botryosphaeria dothidea. This is the first report on the detailed mycological characteristics of the causal organism of post-harvest ripe rot of kiwifruit in Korea.

• The Plant Pathology Journal
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• v.23 no.3
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• pp.166-173
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• 2007

In a trial to select suitable fungicides for developing a spray program that can control apple white rot effectively, after-infection activities in some protective fungicides were detected. Six fungicides, mancozeb, propineb, benomyl, folpet, azoxystrobin and iminoctadine-triacetate, which had been extensively used in apple orchards, were sprayed on 12-year-old apple trees (cv. Fuji) at 15-day intervals from late May to late July. Disease incidences and infection frequencies of the fruit bagged just before and soon after each spray were examined. When the infection frequency or disease incidence of the fruit bagged after each spraying of fungicide was significantly lower than those of the fruit bagged before spraying, the fungicides appeared to confer after-infection activity. The six fungicides showed diverse activities on white rot: folpet showed after-infection activity on disease development, iminoctadine-triacetate showed after-infection activity on infection, azoxystrobin showed after-infection activity on disease development and infection, and mancozeb, propineb and benomyl showed no distinct activity. The activity of a fungicide became much higher when it was sprayed alternately with other fungicide rather than successive spraying of the same fungicide. Analysis of the properties of these protective fungicides could lead to the development of a highly effective spray program against white rot.

• Mycobiology
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• v.29 no.1
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• pp.58-60
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• 2001

A destructive stem rot of wild aster(Aster koraiensis) occurred sporadically some farmers' fields in Guman-myon, Kosonggun, Kyongsangnam-do in 2000. One of the most severely infected field in Kosong showed 28.6 percent of infection rate. The fungus also caused stem or crown rot and systemic wilt or blight of the plants. White mycelium spread over stems and petioles of infected plants and sclerotia formed on the old lesions and near the soil surface. The fungus showed maximum mycelial growth around $30^{\circ}C$ and did not grow under $5^{\circ}C$ and over $45^{\circ}C$ and mycelial width were $4.3{\sim}10.2{\mu}m$. Colony was white, usually many narrow mycelial stand in the aerial mycelium and formed clamp connection. Numerous sclerotia were formed on PDA at $30^{\circ}C$. The shape sclerotia were globoid and $0.8{\sim}3.0{\times}0.9{\sim}3.4$ mm in size. The fungus was isolated repeatedly from the infected tissues and confirmed its pathogenecity to wild aster and identified as Sclerotium rolfsii. This is the first report on the stem rot of wild aster caused by S. rolfsii in Korea.