• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.116.1-116
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• 2003

Fusarium oxysporum f. sp. fragariae is a fungal pathogen causing wilt disease on strawberry. The RAPD and RFLP of IGS region of rDNA were used to identify genetic affinity among 22 isolates of F. oxysporum f. sp. fagariae obtained from various location of major strawberry cultivating areas in Korea. Approximately 2.6kb DNA fragment was amplified with primer CNS1 and CNL12, and polymorphisms were observed with Avail and HinfI. A dendrogram was constructed using the UPGMA for cluster analysis. Eight distinct groups were clustered based on the banding pattern obtained from RAPD and rDNA RFLP. There was high level genetic variation among Korean isolates of Fusarium of sporum f. sp. fragariae.

• Research in Plant Disease
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• v.17 no.1
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• pp.32-37
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• 2011

Field experiments were conducted to evaluate the effectiveness of soil solarization at the Nonsan Strawberry Experiment Station, Korea in 2006 and 2008. In in vitro tests, exposure times to achieve an $LD_{100}$ of Fusarium oxysporum f. sp. fragariae were 6.6 days and 5.1 days at $45^{\circ}C$ and $50^{\circ}C$, respectively. A 100% lethal temperature was $46.7{\pm}0.1^{\circ}C$ for the same fungus. For field trials, solarization was conducted during the summer season using polyethylene mulch in a plastic house. The organic matter+calcium cyanamide+solarization treatment increased pH, organic matter, and calcium content compared to those before treatment in soil analysis, but no effect had an urea+solarization treatment. The temperatures at 10 cm depth were different in each treatment and the highest temperature was recorded from July 30 to August 10. The average temperature in organic matter+calcium cyanamide+solarization treatment at 10 cm depth was $3{\sim}4^{\circ}C$ higher than that in all the other treatments. All solarization treatments reduced the soil population of F. oxysporum f. sp. fragariae at 100% in 2008 relative to the non-treated control. All solarization treatments reduced Fusarium wilt incidence to 0% in 2006 and 2008. The effect of organic matter+calcium cyanamide+solarization against F. oxysporum f. sp. fragariae indicates that there may be future alternatives to traditional solarization for disease control as well as reducing the time needed.

• 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.

• The Plant Pathology Journal
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• v.38 no.6
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• pp.673-678
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• 2022

Vapours from origanum oil (O) and thyme oil (T) were applied to the four soil-borne strawberry pathogens Fusarium oxysporum f. sp. fragariae, Colletotrichum fructicola, Lasiodiplodia theobromae, and Phytophthora cactorum, causing Fusarium wilt, anthracnose, dieback, and Phytophthora rot, respectively. Increasing T vapour doses in the presence of O vapour strongly inhibited mycelial growths of the four pathogens and vice versa. When mycelia of F. oxysporum f. sp. fragariae and P. cactorum exposed to the combined O + T vapours were transferred to the fresh media, mycelial growth was restored, indicating fungistasis by vapours. However, the mycelial growth of C. fructicola and L. theobromae exposed to the combined O + T vapours have been slightly retarded in the fresh media. Prolonged exposure of strawberry pathogens to O + T vapours in soil environments may be suggested as an alternative method for eco-friendly disease management.

• Mycobiology
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• v.32 no.3
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• pp.119-122
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• 2004

The intergenic spacer(IGS) sequence of Fusarium oxysporum have been reported to provide reliable information concerning intraspecific variation and phylogeny of fungal species. The eleven strains of Fusarium oxysporum and its formae speciales belonging to section Elegans were compared with sequencing analysis. The direct sequencing of partial IGS was carried out using PCR with primer NIGS1(5'-CTTCGCCTCGATTTCCCCAA-3')/NIGS2(5'-TCGTCGCCGACAGTTTTCTG-3') and internal primer NIGS3(5'-TCGAGGATCGATTCGAGG-3')/NIGS4(5'-CCTCGAATCGATCCTCGA-3'). A single PCR product was found for each strain. The PCR fragments were sequenced and revealed a few within species polymorphisms at the sequence level. The size of partial IGS sequencing of F. oxysporum was divided into three groups; $526{\sim}527$ bp including F. o. f. sp. chrysanthemi, cucumerinum, cyclaminis, lycopersici, and fragariae; $514{\sim}516$ bp including F. o. f. sp. lilii, conglutinans, and raphani; 435 bp for F. o. f. sp. cucumerinum from Korea. Sequence analysis of PCR products showed that transitions were more frequent than transversions as well as the average numbers of substitution per site were range 0.41% to 3.54%.

• The Plant Pathology Journal
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• v.34 no.3
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• pp.163-170
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• 2018

Strawberry Fusarium wilt disease, caused by Fusarium oxysporum f. sp. fragariae, is the most devastating disease in strawberry production. The pathogen produces chlamydospores which tolerate against harsh environment, fungicide and survive for decades in soil. Development of detection and quantification techniques are regarded significantly in many soilborne pathogens to prevent damage from diseases. In this study, we improved specific-quantitative primers for F. oxysporum f. sp. fragariae to reveal correlation between the pathogen density and the disease severity. Standard curve $r^2$ value of the specific-quantitative primers for qRT-PCR and meting curve were over 0.99 and $80.5^{\circ}C$, respectively. Over pathogen $10^5cfu/g$ of soil was required to cause the disease in both lab and field conditions. With the minimum density to develop the wilt disease, the pathogen affected near 60% in nursery plantation. A biological control microbe agent and soil solarization reduced the pathogen population 2-fold and 1.5-fold in soil, respectively. The developed F. oxysporum f. sp. fragariae specific qRT-PCR protocol may contribute to evaluating soil healthiness and appropriate decision making to control the disease.

• Research in Plant Disease
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• v.26 no.2
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• pp.79-87
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• 2020

Fusarium wilt caused by Fusarium oxysporum f. sp. fragariae (Fof) is the most important diseases of a strawberry field in Korea. We surveyed phylogenetic analysis, pathogenicity test, and fungicide response about Fof isolates isolated from Korea. Twenty-seven isolates of F. oxysporum isolated from strawberry plants were conducted in this study. Specific amplification by Fof specific primer was confirmed in all 26 isolates except Fo080701 isolate. The nuclear ribosomal intergenic spacer region and the translation elongation factor EF-lα gene sequences of isolates revealed three main lineages. Most of all isolates were contained DNA lineage group 1, but 2 and 3 group was shown only one and three isolates, respectively. All isolates were shown in pathogenicity with cv. Seolhyang. The EC₅₀ mean values of prochloraz ranged 0.02-0.1 ㎍/ml except for Fo080701 and effectively inhibited mycelial growth at low concentrations. The EC₅₀ value of metconazole was also 0.04-0.22 ㎍/ml, showing a similar inhibitory effect to that of prochloraz. The EC₅₀ value of pyraclostrobin was 0.23-168.01 ㎍/ml, which was different according to the strain. In the field trial, boscalid+fludioxonil, fluxapyroxad+pyraclostrobin, and prochloraz manganese were selected as the effective fungicides for controlling Fusarium wilt.

• 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.

• Journal of Microbiology and Biotechnology
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• v.30 no.5
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• pp.708-716
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• 2020

The purpose of this study was to identify strawberry wilt pathogens and evaluate the efficacy of Chlorella fusca CHK0059 for improving plant growth and suppressing Fusarium wilt. We identified 10 isolates of wilt pathogens of non-pesticide Seolhyang strawberry plant, including Fusarium oxysporum f. sp. fragariae, using morphological and molecular analysis. On the 15^th day after 0.4% CHK0059 treatment, the plant height of the untreated control strawberry plants was significantly greater than that of the CHK0059-treated strawberry plants. After 85 days, both treatments showed a similar tendency regarding the height of the strawberry plants. However, the thickness of strawberry leaves treated with the CHK0059 was found to be 1 mm thicker than that of the untreated control. The flowering percentage of the CHK0059 plants was also 40.2% higher on average than that of the untreated control. The chlorophyll content of strawberry leaves treated with the CHK0059 was also, on average, 6.63% higher than that of the untreated control. After 90 days of the CHK0059 treatment, the incidence of Fusarium wilt in the CHK0059-treated plants had reduced by 9.8% on average compared to the untreated control. The population density of F. oxysporum f. sp. fragariae was also reduced by approximately 86.8% in the CHK0059-treated plants by comparison to the untreated control at 70 days after treatment. The results indicate that the microalga C. fusca CHK0059 is an efficient biological agent for improving strawberry plant growth and suppressing Fusarium wilt disease in organic strawberries.

• The Korean Journal of Mycology
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• v.47 no.3
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• pp.219-232
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• 2019

Chemicals related to hydrogen peroxide ($H_2O_2$) and nitric oxide (NO) generations were exogenously applied to Fusarium oxysporum f. sp. fragariae (Fof) causing Fusarium wilt disease in strawberry plants, and regulations of in vitro conidial germination and mycelial growth of the fungus by the chemical treatments were evaluated. $H_2O_2$ drastically reduced the conidial germination of Fof in a dose-dependent manner, and treatment with 3-amino-1,2,4-triazole (3-AT) catalase inhibitor also led to dose-dependent inhibition of conidial germination but relatively moderately. Gradual decreases in mycelial growth of Fof were found by high concentrations of $H_2O_2$, whilst exogenous 3-AT slightly increased the mycelial growth. Increasing sodium nitroprusside (SNP) NO donor, $N^G$-nitro-l-arginine methyl ester (L-NAME) NO synthase (NOS)-inhibitor and tungstate nitrate reductase (NR) inhibitor led to dose-dependent reductions in conidial germination of Fof in quite different levels. SNP conversely increased the mycelial growth but increasing L-NAME moderately decreased the mycelial growth. Tungstate strongly enhanced mycelial growth. Differentially regulated in vitro mycelial growths of Fof were demonstrated by SNP, L-NAME and tungstate with or without $H_2O_2$ supplement. Superoxide anion production was also regulated during the mycelial growth of Fof by nitric oxide. These results show that $H_2O_2$ and NO-associated enzymes can be suggested as fungal growth regulators of Fof as well as eco-friendly disease-managing agents in strawberry production fields.