• The Korean Journal of Mycology
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• v.31 no.2
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• pp.117-119
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• 2003

A stem rot of eggplant (Solanum melongena) was found in experimental field of Gyeongsangnam-do Agricultural Research and Extension Services, Korea. The typical symptoms of the disease were stem rot, crown rot, wilt or blight. Upper parts of the infected stems were mostly blighted and white turf of fungal mycelium mats was spread over lesions. Sclerotia were farmed on the stems near soil line. The sclerotia of the fungus eadily were produced in artificial media such as PDA at $30^{\circ}C$. The sclerotia were globoid, $1.0{\sim}3.4mm$ in diameter and brown in color. The optimum temperature for growth of the fungus was about $30^{\circ}C$. The typical clamp connections were found in the hypha formed on PDA, and was $3.8{\sim}10.6{\mu}m$ in size. On the basis of mycological characteristics and pathogenecity test, the fungus was identified as Sclerotium rolfsii. This is the first report of stem rot of eggplant caused by Sclerotium rolfsii in Korea.

• Research in Plant Disease
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• v.9 no.1
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• pp.25-27
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• 2003

In 2002, a stem rot disease was found on Pansy (Viola tricolor) in several road-side flower beds in Jinju City, Gyeongnam province, Korea. The typical symptoms of the disease were stem rot, crown rot, wilt or blight. Upper parts of the infected stems were mostly blighted. White mycelial mats were spread over lesions and the sclerotia were farmed on the stems near soil line. The sclerotia was globoid or irregular in shape, 1.3~4.2 mm in size, and brown in color, The optimum temperature for fungal growth was about 3$0^{\circ}C$. The typical clamp connections were found in the hyphae of the fungus grown on PDA, and hyphal diameter was 3.9~10.4 ${\mu}{\textrm}{m}$. On the basis of mycological characteristics and pathogenecity test on host plants, the fungus was identified as Sclerotium rolfsii. This is the first report on the stem rot of Viola tricolor caused by Sclerotium rolfsii in Korea.

• The Korean Journal of Mycology
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• v.29 no.2
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• pp.131-133
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• 2001

A destructive collar rot disease was found on broad bean (Vicia faba) in several farmer's field located in Changseon-myon, Namhae-gun, Gyeongsangnam-do in 2001. The typical symptoms of the disease were stem rot, crown rot, wilt or blight. Upper parts of the infected stems were mostly blighted and white mycelial mats were spread over lesions and the sclerotia were formed on the stems near soil line. The infection rates of the disease in the surveyed area were ranged from 28.6 to 42.8%. The sclerotia of the fungus readily formed in artificial media such as PDA at $30^{\circ}C$ and its shape was globoid or irregular and size was $1.0{\sim}3.7{\times}1.0{\sim}2.8\;mm\;(av.\;1.0{\sim}2.3\;mm)$ and was brown or dark brown in color. The optimum temperature for growth of the fungus was about $30^{\circ}C$. The typical clamp connections were found in the hypha of the fungus grown on PDA. On the basis of mycological characteristics and pathogenecity test on host plants, the fungus was identified as Sclerotium rolfsii. This is the first report on the collar rot of broad bean caused by Sclerotium rolfsii in Korea.

• The Plant Pathology Journal
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• v.27 no.1
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• pp.78-84
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• 2011

Antagonistic rhizobacteria, more specifically fluorescent pseudomonads and certain species of Bacillus, are known as biocontrol agents of fungal root diseases of agronomic crops. In this study, 144 bacteria were isolated from cucumber rhizosphere and screened as potential biological control agents against Phytophthora drechsleri, the causal agent of cucumber root rot, in vitro condition. Non-volatile compounds of 23 isolates showed noticeable inhibition zone (> 30%) against P. drechsleri, whereas volatile compounds of 7 isolates could prevent more than 30% of the mycelial growth of the fungus. All promising isolates, except of Pseudomonas flourescens V69, promoted significantly plant growth under in vitro condition. P. flourescens CV69 and V11 exhibited the highest colonization on the root. Results of the greenhouse studies showed that a reduction in disease incidence by use of some strains, and particularly use of strains CV6 and V11 as a soil treatment, exhibited a reduction in disease incidence so that suppressed disease by 85.71 and 69.39% respectively. Pseudomonas flourescens CV6 significantly suppressed disease in comparison to Ridomil fungicide. The use of mixture bacterial strains in the soil inoculated by the fungus resulting in falling down the most of the plants which didn't show significant difference with infected control soils without bacteria.

• Research in Plant Disease
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• v.20 no.2
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• pp.126-128
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• 2014

This study was carried out to assay the disease incidence degree of Sclerotium rot caused by Sclerotium rolfsii in sixteen most popular commercial cultivars of sweet potato (Ipomoea batatas) in Republic of Korea. The degree of disease incidence was evaluated on pot experiments. In pot experiments using artificial inoculation, the Sclerotium rolfsii caused a stem rot on seedling of sweet potato plants and causes a crown rot on lower stems near or at the soil line at favorable environmental conditions. White mycelial mats and sclerotia were formed at the infection sites. Plants severely infected were fell over or died because lower stems near soil surface were rotten. The degree of disease incidence was varied according to cultivars. Two cultivars, Bio-mi and Deayumi, were very resistant, while five cultivars, Shinjami, Shingeonmi, Hongmi, Yeonjami, and Shinhung-3 were highly susceptible.

• Research in Plant Disease
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• v.10 no.1
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• pp.21-24
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• 2004

A destructive stem rot of pepper (Capsicum annuum) was found from the often field sporadically in Jingyemyon, Hadong-gun in July 2002 and vinyl houses in Moonsan-eup, Jinju City in October 2003. The same fungus also caused collar and crown rot and systemic wilt or blight of whole plant. White mycelium spread over stems of infected plants and sclerotia formed on the old lesions and near the soil surface. The fungus showed maximum mycelial growth around 3$0^{\circ}C$. The mycelial color is white and width of hyphae ranges 3.6∼10.2 ${\mu}{\textrm}{m}$, and formed clamp connection. Numerous sclerotia were farmed in artificial media such as PDA at 3$0^{\circ}C$. The shape of sclerotia were sphere and 1.0∼2.1 mm in diameter, The fungus was isolated repeatedly from the infected tissues and the pathogenecity of fungus to pepper (Capsicum annuum) was confirmed, and identified as Sclerotium rolfsii. This is the first report on the stem rot of pepper (Capsicum annuum) caused by Sclerotium rolfsii in Korea.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1999.10a
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• pp.36.2-36
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• 1999

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.445-451
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• 1998

A severe Phytophthora rot of strawberry caused by a species of Phytophthora has been widely occurred at major cultivation areas of Kimhae on August in 1997. Incidence of the disease was obtained in the range of 69.2~83.6% in surveyed 4 fields and showed an average of 75.2%. A species of Phytophthora was mostly isolated from the crown of infected strawberry plants and all the isolates were identified as P. nicotianae var. nicotianae (=P. parasitica). The fungus showed strong pathogenicity on strawberry by inoculation test. As a result of the leaf inoculation using mycelial disks of the fungus, both leaves and petioles were darkly browned, and were finally blighted. As a result of the root inoculation of zoospore suspension, both roots and crowns were rotten with dark brown. Although the fungus produced sporangia either on V-8 juice agar medium or liquid medium, the sporangia observed on the liquid medium appeared to be broadly turbinate and noncaducous. Moreover the fungus cultured on the liquid medium often produced sporangia having two papilla. The number of zoospores in sporangia was found to be ranged from 3 or 4 to as many as 20 or 25. In addition, the released zoospore from the sporangium became the cystospore during the prolonged culture of the fungus. The sporangia were measured as av. 49$\times$35 ${\mu}{\textrm}{m}$ with l/b ratio of 1.43. All isolates from crowns were heterothallic and A1 mating type since oospores were abundantly formed on clarified V-8 juice agar by dual culture with P. capsici A2 mating type. Aplerotic oospores were sized 24-26 ${\mu}{\textrm}{m}$. Antheridia were always amphigynous and recoreded an average of 12$\times$10 ${\mu}{\textrm}{m}$. Hyphal swlling were easily observed, and terminal or intercalary chlamydospores were abundantly formed on V-8 juice agar as well as in C/Z solution and sized av. 28.2 ${\mu}{\textrm}{m}$. This is the first report of Phytophthora rot of strawberry in Korea.

• Horticultural Science & Technology
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• v.34 no.2
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• pp.242-248
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• 2016

This research was conducted to determine the effects of four different substrates, expanded rice hulls (ERH), commercial substrates for strawberries (CSS), clay sand (CS), and loamy sand (LS), on the inhibition of anthracnose crown rot (ACR) in strawberry. Mother plants of 'Seolhyang' strawberry were transplanted into an elevated bed in March, 2013 and March, 2014 and the runners connecting mother plants and daughter plants were cut in early August of both years. After separation, growth characteristics of the daughter plants were measured and then each daughter plant was inoculated with conidial suspensions of Colletotrichum fructicola, one of several species of Colletotrichum that causes ACR in strawberries. The incidence of ACR as influenced by the different substrates was investigated in both years. The daughter plants grown on CSS had the highest values for shoot height, leaf area, and fresh weight. Those grown on ERH and LS substrates also displayed good above-ground growth characteristics except for fresh weight, but the daughter plants grown on CS had the poorest above-ground growth characteristics. The ERH and CS treatments resulted in the highest number of primary roots and the greatest root weight. The CSS-grown daughter plants had the highest ACR disease index, followed by the CS and LS treatments, but there were no significant differences among the three substrates. However, the ERH-grown daughter plants had a markedly lower ACR disease index on October 11, 2013 and October 7, 2014. The CSS-grown daughter plants had high nitrogen and potassium contents and low calcium content, whereas the ERH-grown daughter plants had low nitrogen levels and high silicon levels. The results of this study provide basic information on the ability of the different substrates tested to provide disease suppression of ACR in the propagation of strawberry transplants.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.4
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• pp.393-400
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• 2016

Fusarium graminearum is the main cause of substantial economic loss in wheat production. The aim of this study is to investigate biocontrol potential of Lysobacter antibioticus HS124 against F. graminearum and to purify an antifungal compound. In preliminary study, n-butanol crude extract revealed destructive alterations in the hyphal morphology of F. graminearum and almost degraded with $1,000{\mu}g\;mL^{-1}$ concentration. For further study, the antifungal compound extracted from the n-butanol crude extract of L. antibioticus HS124 was identified as N-Butyl-tetrahydro-5-oxofuran-2-carboxamide ($C_9H_{16}NO_3$) using NMR ($^1H-NMR$, $^{13}C-NMR$, $^1H-^1H\;COSY$, HMBC, and HMQC), and HR-ESI-MS analysis. To our knowledge, N-Butyl-tetrahydro-5-oxofuran-2-carboxamide may be a novel compound with molecular weight of 186.1130. The minimum inhibitory concentration value of antifungal compound was $62.5{\mu}g\;mL^{-1}$ against F. graminearum. In an in vivo pot experiment, crown rot disease from F. graminearum was inhibited when wheat seeds were treated with both HS124 culture and F. graminearum. Growth of wheat seedling was enhanced by treatment of HS124 compared to control. Our results suggest that L. antibioticus HS124 characterized in this study could be successfully used to control F. graminearum and could be used as an alternative to chemical fungicides in modern agriculture.