• Mycobiology
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• 제49권2호
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• pp.188-195
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• 2021

The genus Pseudoperonospora, an obligate biotrophic group of Oomycota, causes the most destructive foliar downy mildew disease on many economically important crops and wild plants. A previously unreported disease by Pseudoperonospora was found on oriental pickling melon (Cucumis melo var. conomon) in Korea, which is a minor crop cultivated in the temperate climate zone of East Asia, including China, Korea, and Japan. Based on molecular phylogenetic and morphological analyses, the causal agent was identified as Pseudoperonospora cubensis, and its pathogenicity has been proven. Importantly, two phylogenetic clades of P. cubensis, harboring probably two distinct species, were detected within the same plots, suggesting simultaneous coexistence of the two clades. This is the first report of P. cubensis causing downy mildew on oriental pickling melon in Korea, and the confirmation of presence of two phylogenetic clades of this pathogen in Korea. Given the high incidence of P. cubensis and high susceptibility of oriental pickling melon to this disease, phytosanitary measures, including rapid diagnosis and effective control management, are urgently required.

• The Plant Pathology Journal
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• 제23권3호
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• pp.215-218
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• 2007

The occurrence and relative incidence of viruses including Cucumber mosaic virus (CMV), Zucchini yellow mosaic virus (ZYMV), Papaya rings pot virus (PRSV), and Watermelon mosaic virus (WMV), Cucumber green mottle mosaic virus (CGMMV), Kyuri green mottle mosaic virus (KGMMV), and Melon necrotic spot virus (MNSV) were surveyed from main melon (Cucumis melo L.) production areas in Jeonnam province during 2000-2002. Virus disease incidences of melon cultivating fields were 0% and 11% in spring and fall 2000; 40%, 2.1%, and 8.8% in spring, summer, and fall 2001; and 6.3 % in spring 2002 in main cultivated areas in Jeonnam province, respectively. Field disease incidences of melon virus infections were 0% and 18.8% in spring and fall 2000; 50%, 38.5%, and 82.6% in spring, summer, and fall 2001; and 47.4% in spring 2002, respectively. Total of 101 melon samples showing typical disease symptoms were collected from 2000 to 2002 and tested for virus infection by RT-PCR. Potyvirus-specific DNA fragments for WMV, ZYMV, and PRSV were amplified from 46, 5, and 4 samples, respectively. MNSV specific DNA fragment was amplified from 18 samples. CMV-specific DNA fragment was detected from only 3 samples.

• 한국식물병리학회지
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• 제12권1호
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• pp.116-120
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• 1996

안동지방의 하우스메론 재배농장에서 메론의 과일 및 줄기에 수침상 병반이 관찰되었다. 이 병이 진전되면서 식물의 조직을 연부시키고, 마침내 식물 전체가 말라죽는다. 수침상병반에서 분리된 병원세균의 병원성과 형태적·생리적 특성을 조사한 결과, Erwinia carotovora subsp. carotovora로 동정되었다. 이 병원세균은 국내에서 시판되고 있는 농용항생제 2종과 의약용 항생제 2종에 대해 모두 감수성이었다. 이 병은 한국에서 처음 보고된 것이기에, 병명을 "메론이 세균성무름병(bacterial soft rot of melon)"이라고 부를 것을 제안한다.

• 식물병연구
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• 제29권3호
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• pp.310-315
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• 2023

In May 2021, characteristic soft rot symptoms, including soft, watery, slimy, black rot, wilting, and leaf collapse, were observed on melon plants (Cucumis melo) in Gokseong, Jeollanam-do, Korea. A bacterial strain, designated KNUB-06-21, was isolated from infected plant samples, taxonomically classified, and phylogenetically analyzed using 16S rRNA and housekeeping gene sequencing. Strain KNUB-06-21 was also examined for compound utilization using the API ID 32 GN system and strain KNUB-06-21 was identified as Pectobacterium brasiliense. Subsequent melon stem inoculation studies using strain KNUB-06-21 showed soft rot symptoms similar to field plants. Re-isolated strains shared phenotypic and molecular characteristics with the original P. brasiliense KNUB-06-21 strain. To our knowledge, ours is the first report of P. brasiliense causing melon soft rot disease in Korea.

• 한국작물학회지
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• 제57권4호
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• pp.389-396
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• 2012

Melon (Cucumis melo) is an annual herbaceous plant of the family Cucurbitaceae. Phytophthora rot, caused by Phytophthora capsici is a serious threat to cucurbits crops production as it directly infects the host plant, and it is difficult to control because of variable pathogenicity. This study investigated the resistance of 450 accessions of melon germplasm against Phytophthora rot by inoculating the seedlings with sporangial suspension ($10^{5\;or\;6}$ zoosporangia/ml) of P. capsici. Disease incidence of Phytophthora rot was observed on the melon germplasm at 7-day intervals for 35 days after inoculation. Susceptible melon germplasm showed either severe symptoms of stem and root rot or death of the whole plant. Twenty out of 450 tested accessions showed less than 20% disease incidence, of which five accessions showed a high level of resistance against Phytopthtora rot. Five resistant accessions, namely IT119813, IT138016, IT174911, IT174927, and IT906998, scored 0% disease incidence under high inoculum density of P. capsici ($10^6$ zoosporangia/mL). We recommend that these candidate melon germplasm may be used as genetic resources in the breeding of melon varieties resistant to Phytophthora rot.

• The Plant Pathology Journal
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• 제34권3호
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• pp.182-190
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• 2018

Powdery mildew caused by the obligate biotrophic fungus Podosphaera xanthii poses a serious threat to melon (Cucumis melo L.) production worldwide. Frequent occurrences of the disease in different regions of South Korea hints at the potential existence of several races which need to be identified. The races of five isolates collected from different powdery mildew affected regions were identified based on the pathogenicity tests of these isolates on eight known differential melon cultigens namely, SCNU1154, PMR 45, WMR 29, PMR 5, MR-1, PI124112, Edisto 47 and PI414723. None of the isolates have shown same disease responses to those of the known races tested in this study and in previous reports on these identical differential melon cultigens. This indicates that the tested uncharacterized isolates are new races. Among the isolates, the isolates from Hadong, Buyeo, Yeongam and Gokseong have shown same pathogenicity indicating the possibility of these isolates being one new race, for which we propose the name 'race KN1'. The isolate of Janghueng have also shown unique disease response in the tested differential melon cultigens and hence, we identified it as another new race with a proposed name 'race KN2'. Report of these new races will be helpful in taking effective control measures in prevalent regions and for future breeding programs aimed at developing varieties that are resistant to these race(s).

• 식물병연구
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• 제10권4호
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• pp.260-267
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• 2004

2001년부터 2003년에 걸쳐 수확 후 과일가게에서 판매되는 참외의 썩음증상으로부터 Fusarium spp.를 분리하였다. 병든 과실들은 균사로 덮여 있었고 결국 물러 썩었다. 병의 시작은 주로 과실이 달렸던 부위, 꽃이 달렸던 부위 그리고 열매 표면에 병이 시작되었다. 병이 진전됨에 따라 물러 썩는 열매의 표면에는 흰색에서 분홍빛의 균사로 덮혔다. 이들 병든 과실로부터 분리된 Fusarium spp.를 기존에 보고된 균학적 내용과 비교하여 동정한 결과 Fusarium equiseti, F. graminearum, F. monliforme, F. proliferatum, F. sambucinum, F. semitectum으로 동정되었다. 이들 균의 병원성을 조사하기 위해 건전한 참외에 인위적으로 만든 상처와 무상처에 접종한 결과 접종 이틀후, 상처 접종 부위에 기중균사가 형성되었고, 병이 진전됨에 따라 물러 썩었다. 비록 참외에서 Fusarium spp.가 야기하는 열매썩음병은 국내에서 이미 보고된 바가 있으나, 이와 관련된 종에 대해서는 보고된 적이 없다. 따라서, 이 연구를 통해 Fusarium spp.에 의한 수확 후 참외의 열매썩음병을 국내에서 처음으로 보고하는 바이다.

• 농업과학연구
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• 제47권4호
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• pp.1071-1081
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• 2020

Essential oils (EOs) have been shown to be plant-extracted antimicrobial agents. However, there are limited studies investigating the efficacy of EOs against pathogens. Among them, tea tree oil (TTO) is extracted from Melaleuca alternifolia, which is also used as an antifungal agent. In this study, the effect of TTO was investigated on the suppression of melon powdery mildew caused by Podosphaera xanthii and tomato leaf mold disease caused by Passalora fulva. Both powdery mildew and leaf mold diseases were significantly suppressed by a spray of TTO. Eighty percent of powdery mildew and 81% of leaf mold disease of the control value were suppressed by 0.5% TTO liquid, when sprayed 3 times every 7 days on the melon and tomato leaves. Inhibition of mycelial growth was also greatly affected by different concentrations of TTO against four different fungal pathogens. Ninety-eight percent of Pseudocercospora fuligena, 97% of P. fulva, 95% of Botrytis cinerea, and 94% of Phytophthora infestans mycelial growth were inhibited by 0.2% to 1.0% of TTO contained in plate media, respectively. However, phytotoxicity in plants by the TTO treatments was revealed when melon and tomato leaves were sprayed with a 1% and 2% concentration of TTO, respectively. Therefore, our findings show that TTO has high antifungal effects against various plant pathogens that occur during crop cultivation. We also suggest that when applying TTO to plant leaves, it is necessary to establish an accurate treatment concentration for different crops.

• 식물병연구
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• 제16권3호
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• pp.254-258
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• 2010

Melon necrotic spot virus (MNSV)는 국내에서 재배되고 있는 멜론(Cucumis melo)에 심각한 피해를 주고 있다. 2009년 전남 나주 멜론재배단지에서 괴저반점을 나타내는 멜론 잎에서 MNSV를 분리 동정하였다. 지표식물 반응, immuno captured(IC) RT-PCR 및 염기서열 상동성 비교 등 몇몇 분석으로 이 분리주를 MNSV-Me로 명명하였다. 멜론 시판 35품종에 대한 MNSV-Me의 저항성 선발을 위하여 유묘의 자엽에 인위적 즙액 접종 방법을 이용하였다. 접종된 모든 품종의 자엽에서는 괴저반점을 형성하였다. 이들 중 25품종은 상엽으로 괴저 증상의 이행 또는 일부 개체에서는 접종 약 40일 후 줄기에 3 cm 이상의 괴저를 나타내는 감수성 반응을 나타냈다. 5품종은 상엽으로 잘 이행이 되지 않지만 줄기에 3 cm 미만의 괴저증상을 형성하는 중간 저항성을 발현하였다. 접종한 상엽으로는 바이러스 증상이 발현되지 않고, 단지 줄기에 희미한 괴저가 형성되는 얼스타이탄, 얼스럭서리, 베타리치 하계, 베타리치 및 원더플하계1호가 저항성을 나타냈다.

• The Plant Pathology Journal
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• 제31권4호
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• pp.371-378
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• 2015

Surveys of yellowing viruses in plastic tunnels and in open field crops of melon (Cucumis melo cultivar catalupo), oriental melon (C. melo cultivar oriental melon), and cucumber (C. sativus) were carried out in two melon-growing areas in 2014, Korea. Severe yellowing symptoms on older leaves of melon and chlorotic spots on younger leaves of melon were observed in the plastic tunnels. The symptoms were widespread and included initial chlorotic lesions followed by yellowing of whole leaves and thickening of older leaves. RT-PCR analysis using total RNA extracted from diseased leaves did not show any synthesized products for four cucurbit-infecting viruses; Beet pseudo-yellows virus, Cucumber mosaic virus, Cucurbit yellows stunting disorder virus, and Melon necrotic spot virus. Virus identification using RT-PCR showed Cucurbit aphid-borne yellows Virus (CABYV) was largely distributed in melon, oriental melon and cucumber. This result was verified by aphid (Aphis gossypii) transmission of CABYV. The complete coat protein (CP) gene amplified from melon was cloned and sequenced. The CP gene nucleotide and the deduced amino acid sequence comparisons as well as phylogenetic tree analysis of CABYV CPs showed that the CABYV isolates were undivided into subgroups. Although the low incidence of CABYV in infections to cucurbit crops in this survey, CABYV may become an important treat for cucurbit crops in many different regions in Korea, suggesting that CABYV should be taken into account in disease control of cucurbit crops in Korea.