• Korean Journal Plant Pathology
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• v.11 no.4
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• pp.298-303
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• 1995

The biological control effect of Trichoderma harzianum on the Fusarium wilt of strawberry and several factors affecting on its efficacy were examined through pot experiments. T. harzianum grown on wheat barn, rice straw, rice hull, sawdust or barley straw was respectively incorporated into the pathogen-infected soil, and significantly suppressed the strawberry wilt caused by Fusarium oxysporum f. sp. fragariae. The wheat bran or rice straw culture of T. harzianum suppressed the disease incidence more effectively than other substrates for culture, decreasing it to 68% of the untreated control. The conidial suspension of T. harzianum alone or the suspension mixed with crab shell also effectively reduced the disease incidence. The control effectiveness of T. harzianum was high in acid soil (pH 3.5~5.5). In sandy loam soil, the disease incidences and population densities of the pathogen were decreased by the treatment of T. harzianum, while there was no significant effect of T. harzianum on the pathogen in loam soil.

• Horticultural Science & Technology
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• v.29 no.3
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• pp.273-277
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• 2011

Fusarium oxysporum f. sp. fragariae (Fof), the causal agent of crown and root rot in strawberry, is the most serious soilborne disease of nursery plants in Korea. The possibility of infection by Fof through runner propagation from infected mother plants of strawberry cv. 'Kumhyang' was assessed in stolons and daughter plants hanging from raised beds. The number of daughter plants from an infected mother plant in plastic house and photosynthetic photon flux (PPF) system, 280 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ was 2.7 and 3.8 plants after 58 days, respectively. However, healthy mother plants produced 6.5 and 8.4 daughter plants, respectively. The pathogen was detected in the uppermost portion of the stolon after 58 days, but was not detected further down the stolon. After 90 days, it was detected in all portions of the stolon between mother and $1^{st}$ daughter plant and in 60% of all $1^{st}$ daughter plants. The pathogen was not detected in the corresponding portions of the non-infected controls. These results show that infected mother plants can transmit Fof to their daughter plants without passing through the soil and $1^{st}$ daughter was used as mother plant in PPF system for propagating healthy plants.

• Korean journal of applied entomology
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• v.1
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• pp.42-46
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• 1962

1) The purpcse of the present study is to investigate the effects of culture filtrates of Fuarsium oxysporum f. vasinfectum which is known to produce wilt toxin (fusaric acid) on the germination of host plants (sesame, cotton) and non-host plants (wheat, rice). 2) The experiment on the germination of sesame, cotton, wheat and rice seeds in the seed beds separately added with culture filtr ates of 10 differential strains of Fusarium oxysporom f. vasinfectum demonstrated that culture filtrates of most strains of the fungus inhibit or retard the germination of seeds of 4 plants used in this study while those of a few strains do not give notable influence on the germination of seeds of those plants. a) Culture filtrates of strain 201 of the fungus strongly inhibited the germination of seeds of those plants in nearly same degree, but culture filtrates of the other strains, 281, 321, etc., showed remarkable differences in the toxicity inhibiting or retarding the germination of the seeds of those plants. b) In general, sesame seeds are greatly susceptible, wheat and cotton seeds are moderately susceptible and rice seeds are resistant to the toxicity of culture filtrates of the fungus. 3) In the soil containing a number of differential strains of Fusarium oxysporum f. vasinfectum, the germination of seeds and also the growth of seedlings of non-host plants are possibly checked by the toxic substance, fusaric acid produced by the fungus.

• Applied Biological Chemistry
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• v.50 no.1
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• pp.18-22
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• 2007

The optimum production condition for the antibiotic from Bacillus thuringiensis BK4 was determined, and the suppression rate of Fusarium-wilt by the butanol-extracted antibiotic was verified by employing tomatoes in vitro and in vivo pot tests. Cell growth and antifungal activity were the best when 0.5% xylose and 0.2% peptone No.3 were given as carbon and nitrogen sources, respectively, in the presence of 5mM $CaCl_2$. The partially purified antibiotic successfully prevented Fusarium oxysporum pathogen in pot experiments. When the pots were treated with both live cells and the partially purified antibiotic, an additive-effect was seen in the suppression of Fusarium-wilt, but synergistic effect was not detected. The antibiotic, denoted BK4, purified by Sephadex LH-20 column chromatography was eluted with a single peak at a retention time of 38 min. on prep-HPLC; Minimum inhibition concentration of the homogenous antibiotic was determined to be 50${\mu}$g/ml.

• Horticultural Science & Technology
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• v.31 no.5
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• pp.626-632
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• 2013

In the course of a developing screening method for resistant radish to Fusarium oxysporum f. sp. raphani, we found that the fungus produces phytotoxic compound against Raphanus sativus. The culture filtrate of F. oxysporum f. sp. raphani KR1 represented the strongest phytotoxicity when the fungus was incubated in the malt extract broth with 150 rpm at $25^{\circ}C$ for 14 days. Under bioassay-guided purification, we isolated a substance from liquid culture of F. oxysporum f. sp. raphani KR1, with phytotoxic effect against R. sativus. The compound was identified as fusaric acid by mass and nuclear magnetic resonance spectral analyses. Phytotoxicity of the compound against cruciferous vegetable crops, including radish, cabbage, and broccoli, was investigated. Fusaric acid represented phytotoxicity on radish seedlings by concentration dependant manner. And the phytotoxin demonstrated strong phytotoxicity on the resistant cultivars as well as susceptible cultivars of radish to F. oxysporum f. sp. raphani. In addition, fusaric acid isolated from the fungus also showed a potent phytotoxic efficacy against non-host Brassicaceae crops of the fungus such as cabbage and broccoli. The results demonstrate that fusaric acid produced by F. oxysporum f. sp. raphani is non-host-specific toxin and for screening of resistant radish to the fungal pathogen, spore suspension of the fungus without the phytotoxin has to be used.

• Korean Journal Plant Pathology
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• v.12 no.1
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• pp.33-40
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• 1996

우리나라 여러 딸기 재배지에서 전형적인 시들음 증상을 나타내는 이병식물에서 분리한 32개의 Fusarium oxysporum 균주들을 vegetative compatibility와 전기영동에 의한 동위효소상의 차이에 의해 분류하고 이들과 병원성과의 관계를 알아보았다. Nitrate nonutilizing(nit) mutant를 이용하여 vegetative compatibility group으로 분류해 본 결과 크게 A, B, C, D의 4개 그룹으로 나눌 수 있었으며 A그룹에는 15개 균주, B그룹에는 7개 균주, C와 D그룹에는 각각 2개 균주, 그리고 single VCG인 6개 균주가 존재하였다. 전기영동에 의한 esterase, catalase, acid phosphatase, leucin-aminopeptidase(LAP)의 동위효소상을 비교하여 본 결과 I, II, III, IV의 4개 그룹으로 나눌 수 있었으 I 그룹에는 18개 균주, II그룹에는 2개 균주, III그룹에는 6개 균주, IV그룹에는 6개 균주로 분류할 수 있었다. 또한, VCG의 A와 D그룹에 속하는 모든 균주들의 동위효소상의 I 그룹에 속하였으며 VCG B그룹의 7개 균주들 중에서 5개 균주가 동위효소상의 IV그룹, 7개 균주들 중에서 5개 균주가 동위효소상의 IV그룹, 나머지 2개 균주는 I 그룹과 III 그룹에 속하였으며 C그룹의 균주는 III과 IV 그룹에 속하였고, single VCGs들은 III 그룹에 4개 균주, II 그룹에 2개 균주가 속하므로 VCG와 동위효소상 간에는 밀접한 관계가 있음을 알 수 있었다. 4개 딸기 품종에 대해 병원성을 비교하여 본 결과 VCG A에서 선발된 2개 균주들은 보교조생에 대해 가장 병원성이 강하였으며 정보나 여홍에 대해서도 강한 병원성을 가지고 있었다. 반면에 B 그룹에서 선발된 2개 균주들은 4개 품종에 대해 병원성이 약하거나 거의 없었으며 C 그룹에서 선발된 1개 균주는 여홍에 대해 상대적으로 가장 강한 병원성을 가지고 있었다.

• Research in Plant Disease
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• v.24 no.1
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• pp.26-32
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• 2018

Fusarium wilt on strawberry plants caused by Fusarium oxysporum f. sp. fragariae (Fof) is a major disease in Korea. The prevalence of this disease is increasing, especially in hydroponic cultivation in strawberry field. This study assessed the effect of nutrition solution pH and electrical conductivity (EC) on Fusarium wilt in vitro and in field trials. pH levels of 5.0, 5.5, 6.0, 6.5, 7.0, and 7.5 were assayed in vitro and in field trials. EC levels at 0, 0.5, 0.8, 1.0, and $1.5dS{\cdot}m^{-1}$ were assayed in field trials. Mycelial growth of Fof increased with increasing pH and was highest at $25^{\circ}C$ pH 7 and lowest at $20^{\circ}C$, pH 5.0 in vitro. The incidence of Fusarium wilt was lowest in the pH 6.5 treatment and highest in the pH 5 treatment in field trials. At higher pH levels, the EC decreased in the drain solution and the potassium content of strawberry leaves increased. In the EC assay, the severity of Fusarium wilt and nitrogen content of leaves increased as the EC increased. These results indicate that Fusarium wilt is related to pH and EC in hydroponic culture of strawberry plants.

• Applied Biological Chemistry
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• v.48 no.1
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• pp.40-47
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• 2005

In order to develop a multi-microbial biofungicide against several important plant pathogenic fungi, strains were isolated from the phtophthora blight suppressive red-pepper field soil of Gyeongsangbuk-do, Korea. Strains AY1, AY6, AB1, BB2 and F4, which had strong antagonistic ability against Phytophthota capsici and Fusarium oxysporum, were selected for their involvement with strains of biocontrol fungicide. There were no antagonism among the selected strains and were compatible for making the biofungicide. Their antagonistic mechanisms, except for strain BB2, were an antibiosis by the production of antibiotic, while BB2 produced not only an antibiotic but also cellulase as an antagonistic mechanism against blight causing P. capsici. They were identified as Halobacterium sp. AB1, Xenorhadus sp. AY1, Bacillus sp. AY6, Bacillus sp. BB2, Zymomonas sp. F4 by various cultural, biochemical test and $Biolog^{TM}$ System 4.0. The highest levels of antifungal antibiotic could be produced after 48 hrs of incubation under the optimal medium which were 0.1% galactose, 0.1% $NaNO_2$, 5 mM $Na_2{\cdot}HPO_4$ (pH 5.5). The cultured multi-microbial biofungicide showed strong biocontrol activity against bacterial wilt disease and fusarium wilt disease in cucumber and tomato fields.

• The Korean Journal of Mycology
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• v.25 no.4 s.83
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• pp.354-361
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• 1997

The antifungal activities of 153 extracts from 51 species of Korean mushroom on six phytopathogenic fungi were investigated. The powder of fruit-body of each mushroom was extracted with petroleum ether, 80% ethanol and distilled water. The water extracts of four mushrooms including Amanita virosa showed antifungal activities on Alternaria alternata, Colletotrichum graminicola, Fusarium solani, Idriella bolleyie. The 80% ethanol extracts of seven mushrooms including Boletus auripes showed antibiotic activities against A. alternata, C. gramincola, Cylindrocarpon destructans, F. solani, F. oxysporum cucumerinum, and I. bolleyie. The petroleum ether extracts of six mushrooms including Amanita citrina showed antibiotic activities against A. alternata, C. destructans, and C. graminicola. The 102 extracts of 34 mushrooms including Agaricus arvensis didn't show antibiotic activities.

• Korean Journal of Food Science and Technology
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• v.44 no.5
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• pp.634-637
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• 2012

In strawberry production, among others, the high incidence of diseases by pathogenic fungi resulting in the reduction of fruit yield and quality requires the development of eco-friendly management systems rather than chemical sprays to control them. The diameter of colonies grown in media at $25^{\circ}C$ for 5 days was measured to evaluate the in vitro inhibition of mycelial growth of 5 pathogenic fungi by irradiation with ultraviolet (UV-C, 264 nm). The mycelial growth of 5 pathogenic fungi was inhibited in potato dextrose agar (PDA) by the irradiation of UV-C for 1 hour a day, and was dramatically inhibited by the irradiation of UV-C for 9-12 h a day. The irradiation of UV-C for 9-12 h a day inhibited completely the growth of the late blight pathogen, Phytophthora cactorum. The irradiation distance of 40 to 50 cm was effective for the inhibition of mycelial growth of fungi. The mycelial growth of fungi without pre-incubation was inhibited strongly by UV-C irradiation compared to fungi pre-incubated for 2 days without light. The mycelia growth of Colletotrichum gloeosprioides and Fusarium oxysporum was inhibited strongly by UV-C irradiation in vegetable 8 juice agar compared to PDA.