• The Plant Pathology Journal
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• 제19권3호
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• pp.181-183
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• 2003

Corky root symptoms caused by Pyrenochaeta lycopersici were observed on the roots and stem base of tomato plants in Korea. Symptoms on infected plants typically appeared as stunting and generally lacking vigor, and infected plants die back from the foliage tips after fruits have set. Brown lesions appearing with bands around the roots were characteristic symptoms of the disease. The lesions become swollen and cracked along the length of the root with corky appearance. Based on cultural and morphological characteristics, the fungus from the diseased plants was identified as Pyrenochaeta lycopersici. Pycnidia were solitary, globose to subglobose, brown to black, darker around the neck region, and measured 173-215 $\mu\textrm{m}$ in diameter with septate setae up to 102-132$\times$6.5 $\mu\textrm{m}$. Conidia were hyaline, unicellular, and 4.2-4.7$\times$l.5-2.0 $\mu\textrm{m}$ long. Optimum temperature for mycelial growth of the p. lycopersici isolates ranged from $20^{\circ}C$ to $25^{\circ}C$. Fifteen isolates off lycopersici were tested for pathogenicity to susceptible and tolerant cultivars of tomato plants by artificial inoculation. Three isolates of P. lycopersici induced typical corky root discoloration on susceptible tomato cultivars but not on tolerant tomato. This is the Erst report in Korea of tomato corky root disease caused by P. lycopersici.

• 한국약용작물학회지
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• 제1권2호
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• pp.202-204
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• 1993

택사(澤瀉) 재배실태(載培實態)와 문제점(問題點)을 파악하기 위하여 주산지(主産地)인 전남(全南) 승주군(昇州郡) 해용면(海龍面)에서 6년간(年間) 재배(栽培)한 결과(結果)를 대상으로 조사(調査)한 결과(結果)는 다음과 같다. 1. 택사(澤瀉) 육묘시(育苗時) 제초제(除草劑) 전용(傳用) 약제(藥劑) 개발(開發)이 시급(時急)하다. (현재(現在)로서는 인력(人力) 이용(利用)을 하고 있으나 노동력(勞動力)이 문제(問題)가 된다. ) 2. 벼 극조생종(極早生種) 양질미(良質米) 수도(水稻) 품종(品種) 개발(開發)이 시급(時急)하다. 3. 택사내병(澤瀉耐炳) 다수성(多收性) 양질(良質) 품종(品種) 육성(育成)이 시급(時急)하다. 4. 병충해(病蟲害) 방제(防除)는 농약(農藥)의 사용(使用)이 아닌 영양요소시비(營養要素施肥)와 유기농법(有機農法)에 의한 내병충성(耐炳蟲性) 재배법(裁培法) 개선(改善) 연구(硏究)가 시급(時急)하다.

• The Plant Pathology Journal
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• 제26권4호
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• pp.367-371
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• 2010

In this study, we evaluated the efficacy of fluopicolide to inhibit Phytophthora capsici in vitro, and to control pepper Phytophthora blight in a greenhouse and pepper fields. Fluopicolide was tested on various developmental stages of P. capsici 06-143 (a sensitive isolate to metalaxyl) and JHAW1-2 (a resistant isolate to metalaxyl). Mycelial growth and zoosporangium germination of both isolates were completely inhibited at $4.0\;{\mu}g/ml$ of the fungicide in vitro. The $EC_{50}$ (effective concentrations reducing 50%) of P. capsici 06-143 against zoospore were $0.219\;{\mu}g/ml$, while those of JHAW1-2 were $3.829\;{\mu}g/ml$. When fluopicolide was applied at 100 and $1,000\;{\mu}g/ml$ 7 days before inoculation with P. capsici 06-143 in the greenhouse test, the disease was controlled completely until 6 days after inoculation. However, the curative effect of fluopicolide was not as much as the protective effect. When fluopicolide was applied by both soil drenching and foliar spraying, the treatments strongly protected pepper against the Phytophthora blight disease. Based on these results, fluopicolide can be a promising candidate for a fungicide to control P. capsici in the pepper fields.

• The Plant Pathology Journal
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• 제35권5호
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• pp.437-444
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• 2019

Chlorine dioxide ($ClO_2$) has been widely used as an effective disinfectant to control fungal contamination during postharvest crop storage. In this study, Fusarium oxysporum f. sp. batatas SP-f6 from the black rot symptom of sweetpotato was isolated and identified using phylogenetic analysis of elongation factor 1-${\alpha}$ gene; we further examined the in vitro and in vivo inhibitory activities of $ClO_2$ gas against the fungus. In the in vitro medium tests, fungal population was significantly inhibited upon increasing the concentration and exposure time. In in vivo tests, spore suspensions were drop-inoculated onto sweetpotato slices, followed by treatment using various $ClO_2$ concentrations and treatment times to assess fungus-induced disease development in the slices. Lesion diameters decreased at the tested $ClO_2$ concentrations over time. When sweetpotato roots were dip-inoculated in spore suspensions prior to treatment with 20 and 40 ppm of $ClO_2$ for 0-60 min, fungal populations significantly decreased at the tested concentrations for 30-60 min. Taken together, these results showed that $ClO_2$ gas can effectively inhibit fungal growth and disease development caused by F. oxysporum f. sp. batatas on sweetpotato. Therefore, $ClO_2$ gas may be used as a sanitizer to control this fungus during postharvest storage of sweetpotato.

• 한국버섯학회지
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• 제12권2호
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• pp.132-137
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• 2014

균상느타리버섯에서 발생하는 곰팡이 병해 중에서 가장 많은 문제를 발생하는 것은 Trichoderma disease 또는 green mould 등으로 불리우는 푸른곰팡이병이다. 이 병은 Trichoderma, Penicillium, Aspergillus 등의 속(genus)에 포함되는 종들에 의해 발병되는 병을 총칭하는 것으로 발생빈도와 피해가 가장 큰 것은 Trichoderma 속의 병원균에 의해 발생하였다. 느타리버섯 균상에 분리된 병원균은 T. longibrachiatum, T. koningii, Trichoderma virens, T atroviride, T. hazianum, T. pseudokoningii 6종이었으며, 발생빈도가 높은 것은 T. virens, T. hazianum, T. longibrachiatum 3종이었고, 각각의 균은 배양적 특성 및 병원성도 각기 다른 특성을 보이고 있었다. T. longibrachiatum 균사생장이 매우 빠르고, 포자형성이 빠르며, 특히 후막포자형성이 잘되는 특성을 있으며, 후기에는 진한 녹색으로 변색된다. Trichoderma koningii는 균사생장은 빠르고, 공중균사가 많은 편이며, 포자는 공중균사에 밀집되어 형성된다. 특히 Trichoderma virens 같은 경우에는 포자형성에 의한 색깔변화가 느리며, 감염후기에 발견되어 그 피해가 심한 편이었다. Trichoderma atroviride. 균사생장은 보통이며, 포자형성은 공중균사에 드물게 형성되며, 후기에는 진녹색을 띤다. 이균의 특징은 coconut 냄새와 유사한 향기가 나는 것이다. T. hazianum은 초기에는 균사가 백색으로 매우 빠르고, 공중균사에 포자가 형성하며, 후기에는 진한 녹색으로 변색된다. 공중 균사에 형성된 포자는 육안적으로 pustules or tufts의 형태를 나타내었다. Trichoderma pseudokoningii 균사생장은 빠르며, 포자형성은 접종부위를 중심으로 형성되며, 후기에는 환무니를 형성하며, 특히 배지 색이 변색되고 후막포자 잘 형성되는 특징이 있었다.

• 농약과학회지
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• 제20권2호
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• pp.165-171
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• 2016

도라지와 더덕은 고소득 작물로서 주목받고 있다. 최근 소득을 위해 작물을 연작하는 경우 연작피해로서 뿌리썩음병의 발병이 급속도로 증가하고 있다. 뿌리썩음병은 근채류 식물의 뿌리를 가해하여 큰 경제적 타격을 입히므로 방제가 시급하나 명확한 방제법이 개발되어 있지 않다. 이에 본 연구는 화학약제 tebuconazole EC, trifloxystroim SC, 유기농자재인 자몽 종자 추출물을(GSE) 이용하여 뿌리썩음병 방제 실험을 진행한 결과 더덕에서 친환경제제가 좋은 효과를 보였으나 도라지와 더덕에서 약제의 특성에 따라 큰 차이를 보이지 않았다. 단 재배조건이 배수가 용이한 경우 발병도의 감소와 병방제의 효과가 증진됨을 확인 하였다. 이에 근채류의 뿌리썩음병의 예방 및 방제의 근복적인 대책으로 재배지의 배수가 중요한 원인으로 보여지는 바이다.

• The Plant Pathology Journal
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• 제39권1호
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• pp.1-20
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• 2023

In the past, rice bakanae was considered an endemic disease that did not cause significant losses in Korea; however, the disease has recently become a serious threat due to climate change, changes in farming practices, and the emergence of fungicide-resistant strains. Since the bakanae outbreak in 2006, its incidence has gradually decreased due to the application of effective control measures such as hot water immersion methods and seed disinfectants. However, in 2013, a marked increase in bakanae incidence was observed, causing problems for rice farmers. Therefore, in this review, we present the potential risks from climate change based on an epidemiological understanding of the pathogen, host plant, and environment, which are the key elements influencing the incidence of bakanae. In addition, disease management options to reduce the disease pressure of bakanae below the economic threshold level are investigated, with a specific focus on resistant varieties, as well as chemical, biological, cultural, and physical control methods. Lastly, as more effective countermeasures to bakanae, we propose an integrated disease management option that combines different control methods, including advanced imaging technologies such as remote sensing. In this review, we revisit and examine bakanae, a traditional seed-borne fungal disease that has not gained considerable attention in the agricultural history of Korea. Based on the understanding of the present significance and anticipated risks of the disease, the findings of this study are expected to provide useful information for the establishment of an effective response strategy to bakanae in the era of climate change.

• The Plant Pathology Journal
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• 제22권4호
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• pp.348-352
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• 2006

Barley mild mosaic virus(BaMMV) is a soilborne Bymovirus vectored by root-infecting fungus, Polymyxa graminis. Mechanism of cultivar's resistance to BaMMV in field tests are difficult to assess since resistance could be either due to the virus or to P. graminis, or both. Whereas, available mechanical inoculation methods for BaMMV and other related viruses are labor intensive, give inconsistent results and generally result in low infection rates. Inoculation method using stick with gauze(SWG) was developed for BaMMV. The improved method proved to be simple, efficient, and reliable. The infected leaf tissues were preserved by drying in a frozen state under high vaccum(freeze dried barley infected leaves) to circumvent reduction of virus infectivity during storage. Five Korean barley cultivars were mechanically inoculated with BaMMV-infected sap by the improved method. Infection rates obtained were compared with natural infection. Cultivar Naehanssalbori showed resistance to BaMMV in the field trials but was found highly susceptible in the greenhouse tests by mechanical inoculation, indicating that the field resistance may be possibly due to resistance to P. graminis.

• The Plant Pathology Journal
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• 제36권4호
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• pp.346-354
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• 2020

Pectobacterium, which causes soft rot disease, is divided into 18 species based on the current classification. A total of 225 Pectobacterium strains were isolated from 10 main cultivation regions of potato (Solanum tuberosum), napa cabbage (Brassica rapa subsp. pekinensis), and radish (Raphanus sativus) in South Korea; 202 isolates (90%) were from potato, 18 from napa cabbage, and five from radish. Strains were identified using the Biolog test and phylogenetic analysis. The pathogenicity and swimming motility were tested at four different temperatures. Pectolytic activity and plant cell-wall degrading enzyme (PCWDE) activity were evaluated for six species (P. carotovorum subsp. carotovorum, Pcc; P. odoriferum, Pod; P. brasiliense, Pbr; P. versatile, Pve; P. polaris, Ppo; P. parmentieri, Ppa). Pod, Pcc, Pbr, and Pve were the most prevalent species. Although P. atrosepticum is a widespread pathogen in other countries, it was not found here. This is the first report of Ppo, Ppa, and Pve in South Korea. Pectobacterium species showed stronger activity at 28℃ and 32℃ than at 24℃, and showed weak activity at 37℃. Pectolytic activity decreased with increasing temperature. Activity of pectate lyase was not significantly affected by temperature. Activity of protease, cellulase, and polygalacturonase decreased with increasing temperature. The inability of isolated Pectobacterium to soften host tissues at 37℃ may be a consequence of decreased motility and PCWDE activity. These data suggest that future increases in temperature as a result of climate change may affect the population dynamics of Pectobacterium.

• The Plant Pathology Journal
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• 제30권1호
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• pp.25-32
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• 2014

Fusarium head blight (FHB; scab) caused mainly by Fusarium graminearum is a devastating disease of wheat and barley around the world. FHB causes yield reductions and contamination of grain with trichothecene mycotoxins such as deoxynivalenol (DON) which are a major health concern for humans and animals. The objective of this research was to develop an easy seed or seedling inoculation assay, and to compare these assays with whole plant resistance of twenty-nine Korean winter wheat cultivars to FHB. The clip-dipping assay consists of cutting off the coleoptiles apex, dipping the coleoptiles apex in conidial suspension, covering in plastic bag for 3 days, and measuring the lengths of lesions 7 days after inoculation. There were significant cultivar differences after inoculation with F. graminearum in seedling relative to the controls. Correlation coefficients between the lesion lengths of clip-dipping inoculation and FHB Type II resistance from adult plants were significant (r=0.45; P<0.05). Results from two other seedling inoculation methods, spraying and pin-point inoculation, were not correlated with adult FHB resistance. Single linear correlation was not significant between seed germination assays (soaking and soak-dry) and FHB resistance (Type I and Type II), respectively. These results showed that clip-dipping inoculation method using F. graminearum may offer a real possibility of simple, rapid, and reliable for the early screening of FHB resistance in wheat.