• The Plant Pathology Journal
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• 제37권6호
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• pp.681-686
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• 2021

It is difficult to distinguish melanose and melanoses-like symptoms with the naked eye because they appear similar. To accurately detect melanose symptoms caused by Diaporthe citri from melanose-like symptoms, we developed PCR-based specific primers Dcitri by aligning the internal transcribed spacer (ITS) region of D. citri with the ITS of Diaporthe cytosporella, Diaporthe foeniculina, Colletotrichum gloeosporioides, Botrytis cinerea, Alternaria citri, and Fusarium oxysporum found on citrus peel. PCR results showed that the specific product was amplified in D. citri but not in other isolates including, C. gloeosporioides, B. cinerea, A. citri, F. oxysporum. In addition, specific products were observed in melanose symptoms caused by D. citri but not in melanose-like symptoms, such as copper-injury, sunscald, damages by yellow tea thrips, and pink citrus rust mite. Using the Dcitri primers developed in this study, it is expected that melanose caused by D. citri could be accurately distinguished from melanose-like symptoms.

• 농약과학회지
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• 제13권4호
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• pp.332-335
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• 2009

유기농 인증을 받아서 3년 이상이 경과한 농가의 토양을 수집하여 근권 세균을 450균주 분리하였고, 여러 가지 식물 병원균의 균사 생장을 억제하는 세균 KB-401 균주를 선발하였다. KB-401 균주는 특히 감귤 검은점무늬병균(Diaporthe citri)의 균사 생장과 포자 발아를 억제하며, 발아하는 포자에 처리하였을 때 발아관의 선단이 팽윤되는 현상을 관찰할 수 있었다. 본 균주는 생리적인 특성과 16S rDNA의 염기서열을 분석한 결과, Bacillus subtilis로 동정되었다.

• 식물병연구
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• 제10권2호
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• pp.94-99
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• 2004

청견과 퐁깐의 교배종인 부지화 감귤은 그 모양이 독특하고 당 함량이 높은 고품질의 감귤로서 최근 재배면적과 농가수가 크게 증가하고 있는 품종이다. 대부분이 비닐하우스에서 재배되기 때문에 병이 크게 문제가 되지 않았지만 최근 몇몇 농가에서 병이 발생하여 큰 피해를 주는 경우가 있었다. 조사 결과 부지화 하우스에서 주로 발생하는 병은 Phytophthora citrophthora에 의한 역병, Alternaria sp.에 의한 배꼽썩음병, Penicillium digitatum에 의한 녹색곰팡이병, Botrytis cinerea에 의한 잿빛곰팡이병, Diaporthe citri에 의한 꼭지썩음병 그리고 Xanthomonas axonopodis pv. citri에 의한 궤양병 등 6종이 조사되었다.

• 한국환경과학회지
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• 제29권10호
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• pp.997-1002
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• 2020

In this study, we investigated the effects of the eco-friendly chemical bio-sulfur, on the citrus melanose-causing pathogen, Diaporthe citri, and on the pest, Panonychus citri. In an open field experiment with a plot-scale application of the chemicals: Mancozeb, lime sulfur, lime sulfur + machine oil, and bio-sulfur, the control group showed 70.6% disease severity compared with 10.3% for the Mancozeb-treated group. Among the eco-friendly treatments, disease severity was the lowest for the group treated with lime sulfur + machine oil (32.2%) and was 53.9%, 58.8%, and 58.1% following treatment with lime sulfur, and bio-sulfur diluted 500 and 1000 times, respectively. The proportion of diseased fruit showed similar results, suggesting that bio-sulfur is an effective alternative to lime sulfur. Three days after treatment acaricidal effects on P. citri showed a 197.6% control survival rate whereas the machine oil, and bio-sulfur diluted 500 and 1000 times treatments showed rates of 2.9%, 5.8%, and 9.0%, respectively. After three days, the control value for bio-sulfur diluted 1000 times was 73.2% compared with the values for the machine oil (96.4%) and bio-sulfur diluted 500 times (94.6%) treatments. Therefore, we suggest that additional research is needed on the combined application of bio-sulfur and oils to enhance the additive control effect on citrus melanose and Panonychus citri.

• 한국유기농업학회지
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• 제25권2호
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• pp.295-310
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• 2017

본 연구는 자생식물 참나무과(Fagaceae)인 붉가시나무, 참가시나무, 종가시나무, 개가시나무, 구실잣밤나무 5종을 이용하여 친환경 농자재로 개발을 위한 기초자료를 제공하고자 수용성 추출액 농도에 따른 Colletotrichum gloeosporioides, Diaporthe citri, Phytophthora capsici 등 5종의 작물 병원균에 하여 생장을 조사하였다. 공여체식물별에 따른 수용성 추출액 농도가 증가됨에 따라 작물 병원균 균사의 생장이 감소하는 경향을 보이나 공여체식물과 병원균의 종류에 따라 억제의 정도차이를 보였다. 구실잣밤나무의 수용성 추출액인 경우 Diaporthe citri, Phytophthora capsici, Pythium graminicola에 대하여 25% 처리구에서 약 84%의 균사 생장을 억제하였고 50% 이상 처리구에서는 87%의 균사 생장을 억제하는 것으로 분석되었다. Diaporthe citri의 경우 붉가시나무 수용성 추출액에서는 균사의 생장을 억제하지 못하는 것으로 분석되었다. 참가시나무, 종가시나무, 개가시나무는 15% 내외로 미비하게 균사생장을 억제 되었다. 항균활성을 보이는 수용체식물의 총 페놀 함량은 구실잣밤나무 22.32 mg/g, 참가시나무 8.32 mg/g, 종가시나무 6.83 mg/g, 개가시나무 5.95 mg/g, 붉가시나무 5.24 mg/g 순으로 분석되었으며, 참나무과 5종 중 구실잣밤나무의 수용성 추출액이 가장 항균력이 우수한 것으로 판단된다.

• 식물병연구
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• 제9권3호
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• pp.153-158
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• 2003

제주도 감귤원에서 문제가 되고 있는 검은점무늬병의 발병원인을 구명하기 위하여 병원균의 분리동정과 병원성을 조사하였다. 감귤의 마른가지로부터 분리된 병원균은 불완전세대인 Phomopsis citri(완전세대 Diaporthe citri)로 확인되었다. 각 지역 감귤원에서 수집분리한 18개 균주의 분생포자각의 크기는 11.2~614.4${\mu}m$ 범위로 평균 크기는 328.8${\mu}m$였으며 균주별로 크기가 다소 상이하였다. 병포자는 ${\alpha}$포자와 ${\beta}$포자 2종류가 관찰되었으며 ${\alpha}$포자는 무색 단포로 타원형이었고, ${\beta}$포자는 무색 단포로 사상형이며 활처럼 약간 구부러졌고 대개의 경우 한쪽 끝이 휘어 있었다. 크기는 ${\alpha}$포자가 평균 6.7 ${\times}$ 2.3${\mu}m$ 였고, ${\beta}$포자는 22.1 ${\times}$ 1.0${\mu}m$ 였다. 균주별 병원성 검정결과 모든 균주에서 검은점무늬병의 발병이 확인되었으며 균주에 따라 병원성의 차이가 있었다.

• 식물병연구
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• 제24권2호
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• pp.132-137
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• 2018

유자 검은점무늬병은 Diaporthe citri가 원인균이며, 과실에 발병하여 심각한 피해를 초래한다. 병자각으로부터 분생포자가 누출될 때, 습윤은 병원균 감염에 중요한 환경 요소이다. 발아과정 중 병포자가 건조에 처하거나 습윤중단이 발생할 때 발아율에 어떤 영향을 주는지 알아보았다. 건조 처리는 포자현탁액을 슬라이드 글라스에 0-48시간 동안 처리하였다. 습윤 중단 처리는 포자현탁액을 습윤에 10시간 먼저 노출한 후, 0-6시간 건조시켜 발아과정에서 습윤을 중단시켰다. 15시간 이상 건조 처리한 포자 발아율은 10% 이하였다. 3시간 이상 습윤 중단 처리된 포자 발아율은 35% 이하였다. 다른 식물병원성 곰팡이와 비교하면, D. citri는 건조에 민감한 곰팡이다. 유자 과피 배지 위에 다양한 온도(15, 20, 25, 30, $35^{\circ}C$)별로 습윤 존재시간(3, 6, 9, 12, 15, 18, 24 hr)을 다양하게 처리하여 포자발아율을 측정하였다. 발아율 10%와 50%를 달성하기 위한 최소 수분존재시간은 각각 4.5시간과 13시간이며, 이 때 적온은 각각 $29.2^{\circ}C$와 $29.1^{\circ}C$였다. 다양한 온도에서 발아율 10%와 발아율 50% 달성에 요구되는 최소 수분존재시간을 결정하는 추정식은 각각 $Wh_{10%}=0.082{\times}T^2-4.8025{\times}T+74.861$과 $Wh_{50%}=0.1093{\times}T^2-6.3762{\times}+106.08$이었다.

• 식물병연구
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• 제29권2호
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• pp.130-136
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• 2023

Citrus melanoses caused by Diaporthe citri, has been one of the serious diseases in many citrus orchards of Jeju Island. To protect melanose in citrus farms, a fast and exact diagnosis method is necessary. In this study, diseased leaves and dieback twigs were collected from a total of 49 farms within March to April in 2022. A total of 465 fungal isolates were obtained from a total of 358 isolated plant samples. Among these fungal isolates, 40 representatives of D. citri isolates which were isolated from 22 twigs and 18 leaves on 23 farms were found based on cultural characteristics on potato dextrose agar and conidial morphology. Additionally, the molecular assay was carried out and compared with those by morphological diagnosis. All isolates were identified as D. citri by analyzing the sequences at the internal transcribed spacer (ITS) rDNA region using primers of ITS1/ITS4 or at β-tubulin using primer Btdcitri-F/R. Therefore, based on the present study, where the results of morphological identification of conidial type were consistent with DNA sequence analysis of certain gene, choosing a suitable method for a fast diagnosis of citrus melanose was suggested.

• The Plant Pathology Journal
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• 제35권5호
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• pp.417-424
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• 2019

Melanose, caused by Diaporthe citri, is one of severe diseases in citrus, a major economic resource in Jeju island. To reduce the usage amount of organic synthetic fungicide, bio-sulfur was tested as an alternative chemical to control citrus melanose in the present study. Direct antifungal activity of bio-sulfur against D. citri was determined through in vitro experiment using artificial nutrient media. Disease severity of melanose on bio-sulfur pretreated citrus leaves was lower than that on untreated ones. To illustrate the mechanism of disease suppression by bio-sulfur, infection structures were observed with a fluorescent microscope and a scanning electron microscope. In fluorescent microscopic observation, most conidia rarely germinated. In addition, hyphal growth on leaves pretreated with bio-sulfur was inhibited compared to that on untreated ones. In scanning electron microscope images of bio-sulfur pretreated leaves, surfaces of most conidia were shrunk while hyphae were morphologically changed and frequently branched. Such microscopic observations were also found for leaves pretreated with a commercial fungicide Dithianon. These results suggest that bio-sulfur may be used to control citrus melanose as an environment friendly alternative to organic synthetic fungicides

• The Plant Pathology Journal
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• 제39권4호
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• pp.351-360
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• 2023

Citrus melanose, caused by Diaporthe citri, has been one of the serious diseases, and chemical fungicides were used for protection in many citrus orchards of Jeju Island. Establishing a disinfectant resistance management system and reducing pesticide usage would be important for contributing to safe agricultural production. In this study, monitoring of chemical resistance was performed with 40 representative D. citri isolates from many citrus orchards in Jeju Island. Four different fungicides, kresoxim-methyl, benomyl, fluazinam, and prochloraz manganese, with seven different concentrations were tested in vitro by growing the mycelium of the fungal isolates on the artificial medium potato dextrose agar. Among the 40 fungal isolates, 12 isolates were investigated as resistant to kresoxim-methyl which could not inhibit the mycelium growth to more than 50%. Especially isolate NEL21-2 was also resistant against benomyl, whose hyphae grew well even on the highest chemical concentration. However, any chemical resistance of fungal isolates was found against neither fluazinam nor prochloraz manganese. On the other hand, in vivo bio-testing of some resistant isolates was performed against both kresoxim-methyl and benomyl on young citrus leaves. Typical melanose symptoms developed on the citrus leaves pre-treated with both agrochemicals after inoculation with the resistant isolates. However, no or less symptoms were observed when the susceptible isolates were inoculated. Based on these results, it was suggested that some resistant isolates of D. citri occurred against both systemic fungicides, which may be valuable to build a strategy for protecting citrus disease.