• The Plant Pathology Journal
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• v.39 no.6
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• pp.600-613
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• 2023

Fusarium oxysporum is the main pathogen causing Fusarium basal rot in onion (Allium cepa L.), which incurs significant yield losses before and after harvest. Among management strategies, biological control is an environmentally safe and sustainable alternative to chemical control. In this study, we isolated and screened bacteria for antifungal activity against the basal rot pathogen F. oxysporum. Isolates 23-045, 23-046, 23-052, 23-055, and 23-056 significantly inhibited F. oxysporum mycelial growth and conidial germination. Isolates 23-045, 23-046, 23-052, and 23-056 suppressed the development of Fusarium basal rot in both onion seedlings and bulbs in pot and spray inoculation assays. Isolate 23-055 was effective in onion seedlings but exhibited weak inhibitory effect on onion bulbs. Based on analyses of the 16S rRNA and rpoB gene sequences together with morphological analysis, isolates 23-045, 23-046, 23-052, and 23-055 were identified as Bacillus thuringiensis, and isolate 23-056 as Bacillus toyonensis. All five bacterial isolates exhibited cellulolytic, proteolytic, and phosphate-solubilizing activity, which may contribute to their antagonistic activity against onion basal rot disease. Taken together B. thuringiensis 23-045, 23-046, 23-052, and 23-055 and B. toyonensis 23-056 have potential for the biological control of Fusarium basal rot in onion.

• Mycobiology
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• v.51 no.4
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• pp.264-272
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• 2023

Onion (Allium cepa L.) is an economically important vegetable crop worldwide. However, various fungal diseases, including Fusarium basal rot (FBR), neck rot, and white rot, reduce onion production or bulb storage life. FBR caused by Fusarium species is among the most destructive onion diseases. In this study, we identified Fusarium species associated with FBR in Jeolla and Gyeongsang Provinces in South Korea and evaluated fungicides against the pathogens. Our morphological and molecular analyses showed that FBR in onions is associated with Fusarium commune, Fusarium oxysporum, and Fusarium proliferatum. We selected seven fungicides (fludioxonil, hexaconazole, mandestrobin, penthiopyrad, prochloraz-manganese, pydiflumetofen, and tebuconazole) and evaluated their inhibitory effects on mycelial growth of the pathogens at three different concentrations (0.01, 0.1, and 1 mg/mL). We found that prochloraz-manganese was highly effective, inhibiting 100% of the mycelial growth of the pathogens at all concentrations, followed by tebuconazole. Fludioxonil showed < 50% inhibition at 1 mg/mL for the tested isolates.

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.463-466
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• 1998

A Fusarium species was isolated from stems of cactus(Hylocereus trigonus) showing rot symptoms at Koyang, Kyonggi province in 1997. This pathogen was identified as Fusarium oxysporum based on mycological characteristics. The rot symptom appeared at the soil line and roughly circular lesions, 1∼3 mm in diameter, appeared on basal stems. The pathogen formed both microconidia and macroconidia. Microconidia were formed abundantly in false-heads on short monophialides, oval to kidney-shaped. Macroconidia were slightly sickle-shaped, 3∼5-septated with an attenuated apical cell and a foot-shaped basal cell. Colony color on PDA was white, peach or purple. Chlamydospores were formed abundantly on PDA. The pathogen was able to cause stem rot symptoms to cactus by wound inoculation as well as non-wound inoculation.

• The Plant Pathology Journal
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• v.18 no.4
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• pp.225-227
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• 2002

Moth orchid plants with yellowing blight and root rot symptoms were collected, and a total of 54 isolates of Fusarium spp. was obtained from roots and leaf bases of the diseased plants. The isolates were identified based on their morphological characteristics. Out of the 54 isolates of Fusarium spp., 42 isolates were identified as F. solani, 5 isolates as F. oxysporum, and 7 as F. proliferatum. Isolates of the three Fusarium spp. were tested for pathogenicity to moth orchid plants by artificial inoculation. All the Fusarium spp. induced root rot of the host plants. The symptoms progressed up to the basal part of the leaves, which later caused yellowing blight. The symptoms induced on the plants by artificial inoculation with the Fusarium spp. isolates were similar to those observed in greenhouses. The present study reveals that F. oxysporum, F. proliferatum, and F. solani cause root rot of moth orchid, and that F. solani is the main pathogen of the disease.

• The Plant Pathology Journal
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• v.18 no.3
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• pp.156-160
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• 2002

Cymbidium orchids with blight and rot symptoms were collected, and a total of 63 isolates of Fusarium app. was obtained from pseudobulbs, roots, and leaves of the diseased plants. The isolates were identified based on their morphological characteristics. Out of the 63 isolates of Fusatium sup., 51 isolates were identified as F. oxysporum, 10 isolates as F. solani, and the rest as F. proliferatum. F. oxysporum was isolated from all the Cymbidium spp., while F. solani and F. proliferatum were isolated only from Cymbidium ensifolium and C. ginatum, respectively. Isolates of the three Fusarium spp. were tested for pathogenicity to their hosts by artificial inoculation. The strongly pathogenic isolates of Fusarium spp. induced severe dry rot of pseudobulbs and roots of the host plants. The symptoms progressed up to the basal part of the leaves, which later caused blight of the entire plant. The dry root symptoms induced on the plants by artificial inoculation with the isolates of Fusarium app. were similar to those observed in the growers'greenhouses. This is the first report of dry rot of Cymbidium spp. caused by F. oxysporum, F. solani, and F. proliferatum in Korea.

• Research in Plant Disease
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• v.13 no.1
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• pp.6-14
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• 2007

Root and basal stem rot disease occurred on moth orchid (Phalaenopsis spp.), Pung-nan (Neofinetia falcata) and Nadopung-nan (Aerides japonicum) grown in the farmers' greenhouses located in Namyangju Kyonggi province, Korea during 2005 to 2006. Wilting symptoms occurred on these orchard plants at initial stage and the infected plant leaves turned yellow to red. The discolored leaves were fallen down to lead to eventual death of the entire plant. A total of 59 isolates of Fusarium spp. was obtained from roots and leaf bases of the diseased plants. The cultural and morphological characteristics of isolated Fusairum spp. were identified as Fusarium oxysporum, F. proliferatum and F. solani. F. oxysporum and F. proliferatum were isolated from all these orchard plants but F. solani was isolated only from Phalaenopsis spp. Pathogenicity of the three Fusarium spp. was confirmed by artificial inoculation. Although F. oxysporum, F. proliferatum and F. solani cusing root rot disease in Phalaenopsis spp. have been reported in Korea, the pathogens in N. falcata and A. japonicum were not reported yet. Therefore, this is the first report on the root and stem rot of N. falcata and A. japonicum caused by F. oxysporum and F. proliferatum in Korea.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2002.11a
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• pp.50.2-50
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• 2002

• The Plant Pathology Journal
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• v.28 no.1
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• pp.49-54
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• 2012

In August 2010, a severe crown rot was observed on chrysanthemum ($Chrysanthemum$ $morifolium$ Ramat., variety Sinro) in several greenhouses located at Damyang and Muan, Jeonnam province, Korea. Three isolates (EML-CHS1, -CHS2, and -CHS3) of $Fusarium$ were isolated from the affected plants and identified based on morphological characteristics and rDNA internal transcribed spacer (ITS) sequence analysis. Sequence analysis by BLAST indicated that EMLCHS1, -CHS2 and CHS3 were closest to a $Fusarium$ species, $F.$ $solani$ with > 99% sequence similarity. Pathogenicity tests were performed on chrysanthemum with spore suspensions containing $3.4{\times}10^6$ spores/ml using the dipping method. Ten days after inoculation, similar symptoms to those observed in the greenhouses were seen on the inoculated plants. The causal fungus was reisolated from the artificially inoculated basal stems, fulfilling Koch's postulates. To our knowledge, this is the first report of crown rot by $Fusarium$ $solani$ on chrysanthemum ($Chrysanthemum$ $morifolium$) in Korea.

• The Korean Journal of Mycology
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• v.45 no.1
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• pp.74-82
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• 2017

Lisianthus (Eustoma grandiflorum) is a flowering ornamental plant used widely in Korea. In 2015, wilting, damping-off, stunting, and root rot symptoms were observed in lisianthus plants of Yeoju and Gimhae, Korea. Affected seedlings appeared yellow and showed poor development of root systems in the field and in nursery boxes. Furthermore, affected plants were yellow, stunted, and died at approximately 2-3 months after transplanting. Fusarium species were consistently isolated from the basal stems of diseased plants. Nine isolates were identified as Fusarium solani based on morphological characteristics. Macroconidia of isolates were relatively wide, straight-to-slightly curved, and microconidia formed in false heads on long monophialides. Abundant chlamydospores were produced at the middle or tips of hyphae. To confirm this identification, a molecular analysis of the translation elongation factor 1 alpha (TEF) and RNA polymerase II subunit (RPB2) genes was conducted. The sequences of TEF and RPB2 showed 99.2-99.9% and 98.0-98.1% similarity, respectively, to those of reference F. solani strains in NCBI GenBank. Pathogenicity was tested using root dipping inoculation of healthy lisianthus seedlings. Symptoms were observed within 7 days of inoculation only in inoculated plants. This is the first report of F. solani causing Fusarium root rot on lisianthus in Korea.

• The Plant Pathology Journal
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• v.26 no.3
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• pp.216-222
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• 2010

Fusarium proliferatum is the causal agent of stalk and root rot disease of maize, foot rot disease of rice, basal and root rot disease of onion and knife cut disease of sugarcane in Iran. In recent years, incidence and severity of these diseases have been increased in Iran. Fifty seven F. proliferatum single-spore isolates collected from diseased maize, rice, onion and sugarcane plants at different areas were used to study genetic diversity by determination of vegetative compatibility groups (VCGs). Chlorate-resistant nitrate non-utilizing (nit) mutants were recovered from selected isolates of F. proliferatum and used in complementation tests. All isolates in which both nit1 and NitM (or nit3) mutants were recovered, demonstrated self-compatibility. Vegetative compatibility tests by pairing nit mutants identified 30 VCGs among 57 isolates. Twenty-three isolates belonged to singlemember VCGs and the remaining 34 isolates, belonged to other seven multimember VCGs. Segregation of F. proliferatum isolates obtained from various area and host plants into different VCGs in Iran is reported for the first time. In this study, none of isolates obtained from rice complemented with any other isolates from onion and sugarcane and, non complementation occurred between onion and sugarcane isolates. Also, only one complementation occurred between one isolate of maize and one isolate of sugarcane and rice. Thus, a correlation between VCGs grouping and host preferences was founded. It is concluded that natural populations of F. proliferatum in Iran are probably genetically divergent and include isolates representing a potential risk for disease development.