• Research in Plant Disease
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• v.23 no.3
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• pp.234-240
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• 2017

Incidence of virus diseases in red pepper of open field in Yeongyang-Gun, Gyeongbuk Province was investigated by reverse transcription-polymerase chain reaction in 2012-2016. The infection rate of Cucumber mosaic virus (CMV), Broad bean wilt virus 2 (BBWV2), Pepper mottle virus, Potato virus Y, Pepper mild mottle virus and Tomato spotted wilt virus was 46.1%, 41.5%, 2.0%, 2.0%, 4.4% and 0.1% respectively. Incidence rate of single and mixed infection was 31.2% and 62.6%. Most of single infections were CMV and BBWV2. Among mixed infections, the incidence rate of CMV+BBWV2 mixed infection was the highest as 49.3% and most of mixed infections of triplex and tetraplex included CMV+BBWV2 mixed infection. CMV single infection caused mosaic, chlorosis, yellowing and vein necrosis and BBWV2 single infection induced cholosis and mosaic. CMV+BBWV2 mixed infection caused severe mosaic with chlorosis or malformation.

• Korean Journal of Organic Agriculture
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• v.24 no.3
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• pp.571-582
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• 2016

Bacterial fruit blotch (BFB) is one of most important diseases in Cucurbitaceae due to infection of Acidovorax citrulli, causing huge economic losses damage worldwide. This seedborn disease spread rapidly at period of high temperature and humidity. The eco-friendly farming is getting popular. So far there was no effective agent to control BFB in eco-friendly farming. Therefore, effect of the material based on chinese nut-gall extract with antibacterial activity against BFB to was tested against A. citrulli. Different hosts showed various symptoms of BFB. Liquid formulation among exhibited most effective anti-bacterial activity on A. citrulli. Pot experiment in greenhouse showed the potential as an control agent of BFB in cucurbits. The treatment of material based on chinese nut-gall extract showed the positive effect on survival of the watermelon seedling and on the length of the cucumber seedling treated with A. citrulli. We cautiously conclude that the material based on chinese nut-gall extract used in this study may be good agents against major diseases of cucurbits in the future even though it is require to be tested with more study on field test.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.4
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• pp.71-80
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• 2001

In order to evaluate the effectiveness of the organic and natural farming techniques, the actual conditions of the techniques were surveyed and some crops were cultivated in situ. The contents of available $P_2O_5$, exchangeable $Ca^{2+}$ and organic matter of the organic and natural farming soil as well as soil pH were higher than those of the non-organic and non-natural farming soil, and especially the content of organic matter amounting 54.0 g/kg was dominant. Income of the farmers cultivating the different crops with the organic and natural farming was high in order of red pepper in vinyl house > cucumber in vinyl house > fruit(pear) > lettuce in vinyl house > rice. The agricultural materials used in organic and natural farming were ranged from 22 to 25 kinds, representing low pH amounted from 2.9 to 4.5 and low contents of fertilizer ingredients. The expense for purchasing the materials was from three to five times higher than that of soil testing plot. The yields of test crops in the organic and natural farming plots were lower than those of soil testing plot, and the efficiencies of the disease and pest control by the application of the substitutes for pesticide were lower than those by pesticides.

• The Plant Pathology Journal
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• v.23 no.3
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• pp.143-150
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• 2007

A new virus-like disease of tomato showing chlorotic spots, malformation and necrosis on leaves, and chlorotic blotching, rings, and necrosis on fruits was observed around Sacheon, Gyeongsangnam-do, Korea in 2004. Host range analysis could not differentiate 4 field isolates collected from tomatoes showing different symptoms but identified them as Tomato bushy stunt virus (TBSV). TBSV-tsf2 isolate induced symptoms in indicator plants similar to those caused by the TBSV-C, -S and -Nf. As the isolate could not systemically infect Chenopodium quinoa, the isolate might belong to the previously described TBSV-S isolate. TBSV-tsf2 isolate caused similar cytological alterations that were similar to that generally caused by previously reported TBSV isolates. TBSV-tsf2 isolate, however, could be considered to belong to new strain of TBSV because masses of small electron-dense patches that were not observed from the previously described TBSV. The complete nucleotide sequences of the genomic RNA of 4739 nt excluding non-translated sequences at both termini have been determined and compared to sequences of other TBSV strains. The complete nucleotide sequence identity among TBSV isolates was 98.9% to 99.7%, and to the other tombusviruses ranged from 80.8% to 94.9%. Comparison of the amino acid sequences all five ORFs with those of other TBSV strains shows a similar genomic organization, and high percentage of amino acid sequence homology with TBSV-Nf than TBSV-S isolate. Since the TBSV symptoms were only observed in Sacheon fields where imported seeds from Japan were planted, the TBSV incidence probably caused by the planting contaminated tomato seeds and thus require more through quarantine procedure to prevent settlement of TBSV in Korea. Altogether, these results support that the Korean isolate of TBSV infecting tomato might be new strain.

• Research in Plant Disease
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• v.8 no.2
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• pp.101-106
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• 2002

For the detection of Tobacco masaic virus (TMV), Tomato mosaic virus (ToMV), and Cucumber mosaic virus (CMV), tomato seeds of 11 table tomato and 7 cherry tomato cultivars were assayed by DAS-ELISA. Among the cultivars, TMV and ToMV were detected from 9 cultivars at the rates lower than 20% and 16%, respectively. In the assay on seed transmission rates, ToMV and CMV were detected as high as 24% and 8% , respectively, but TMV was not detected. In field survey on these viruses from tomato plants of 10 different places in Chungbuk province, ToMV and CMV were detected from most fields. TMV was detected from only 3 fields. The highest detection rates of these viruses were recorded in Cheongwon for TMV Chungju for ToMV, and the other locality of Chungju far CMV. It was difficult to find any relationship between the growth stage of tomato and infection rates. TMV usually caused mosaic on leaves while ToMV caused various symptoms including yellows, necrosis, and mottling. CMV-infected tomato plants showed symptoms of shoestring, fern leaf, and yellows.

• Research in Plant Disease
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• v.15 no.2
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• pp.112-119
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• 2009

We discovered two novel phytotoxins produced by the pathogenic fungus, Botrytis cinerea. Among the twenty-five B. cinerea isolates, which were obtained from various host plants in 1994 and 1996, twenty-two showed strong or moderate pathogenicity on five plants such as cucumber, tomato, red pepper, tobacco and Chinese cabbage. The culture filtrate of the B. cinerea 2-16 strain showed the most potent phytotoxic activity in a tobacco leaf-wounding assay. Two novel phytotoxins were isolated from the liquid cultures of B. cinerea 2-16 by ethyl acetate extraction, flash silica gel column chromatography, silica gel column chromatography, Sephadex LH-20 column chromatography, preparative TLC and subsequently preparative HPLC. Their chemical structures were determined to be 3-O-acetyl botcinol and 3-O-acetyl botcinolide, respectively, by mass and NMR spectral analyses. These two phytotoxins caused leaf necrosis in a leaf-wounding bioassay, and significant electrolyte leakage from leaf tissues of tobacco. In the two bioassays tested, 3-O-acetyl botcinol exhibited stronger phytotoxic activity than 3-O-acetyl botcinolide. This is the first report on the production of both 3-O-acetyl botcinol and 3-O-acetyl botcinolide from B. cinerea.

• Applied Biological Chemistry
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• v.40 no.6
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• pp.593-596
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• 1997

In the course of search antagonistic fungi from soil in green house, four kind of fungi (AF1, AF2, AF3, AF4) were isolated, which have activities against Phytophthora capsici, Botrytis cinera, Rhizoctonia solani, Pythium ultimum and Fusarium oxysporum. The AF2 was identified according to the morphological description of Aspergillus terreus. This antagonistic fungus inhibiting various plant pathogens was effective to reduce disease incidence of cucumber seedlings caused by mixed inoculum of Rhizoctonia solani, Pythium ultimum and Fusarium oxysporum. Antifungal compound I was isolated and purified by fresh chromatography from A. terreus. The $^1H$ and $^{13}C$ assignment of compound I was achieved from two-dimensional $^1H-^1H\;COSY$, HMQC, HMBC with the add of homonuclear and heteronuclear double resonance experiment. The compound I was identified butyrolactone I (${\alpha}$-oxo-${\beta}$-(p-hydroxyphenyl)-${\gamma}$-(p-hydroxy-m-3,3-dimethyl-allylbenzyl)-${\gamma}$-methoxycarbonyl-${\gamma}$-butyrolactone, $C_{24}H_{24}O_7$, M.W.=424).

• Korean Journal of Plant Resources
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• v.19 no.5
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• pp.634-639
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• 2006

In order to develop a disease-resistant root stock for the growth of watermelon, an efficient regeneration system of the gourd(Lagenaria leucantha Duch.) inbred line GO701-2 via organogenesis was established in this experiment. Using proximal parts of cotyledon explant excised from germinated seedling in vitro, maximum adventitious shoot formation (39%) was achieved on MS medium where cytokinin (BA) and auxin (IAA) were added at a concentration of 3mg/L and 0.1mg/L, respectively. Roots of the elongated shoots were successfully formed on MS medium without adding any plant growth regulators. The cucumber CsGolS1 gene known as a resistance gene against biotic and abiotic stresses, was constructed into the binary vector pBI121 under the control of CaMV 35S promoter. When the gene was introduced into the genome of gourd by Agrobacterium-mediated transformation, putative transgenic plants were obtained with the transformation efficiency of approximately 20 percent.

• Korean journal of applied entomology
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• v.23 no.2 s.59
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• pp.74-81
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• 1984

The experiments were conducted to study the distribution of wilt of strawberry caused by Fusarium in Korea, the characters of the causal fnngus and its control. The results obtained are summarized as follows. 1. Wilt of strawberry has been found in Gimhae and Samrangjin, Gyeongnam province a few years ago. This disease has been spreading year after year, and observed on farms in most of the strawberry-growing areas in Korea. 2. The fungus was isolated frequently from the crowns and petioles of diseased straw berry plants, and the fungus belonging to Fusariun oxysporum in terms of the morphological characteristics of macroconidia, microconidia, chlamydospore and conidiophore on V-8 Agar. 3. The macroconidia formation of the fungus varied remarkably with the Isolates and kinds of medium tested. However. all isolates abundantly produced macroconidia on V-8 Agar. 4. The cross-inoculation tests with several forma specialis of F. oxysporum to cucumber, tomato, watermelon, luffa, cabbage, melon and strawberry were carried out. The isolates from strawberry viz. Kodama's F. oxysporum f. sp. fragariae and S-1 of the authors were pathogenic to only strawberry. The fungus was also similar in morphology and symptoms to Kodama's and Winks' isolate of F. oxysporum f. sp. fragariae. Therefore, the fungus is identified as Fusarium oxysporum Schl. f. sp. fragariae Winks & Williams. 5. The most effective fungicides were Benomyl and Homai for inhibiting sporulation and mycelial growth of the fungus. 6 The cultivar Kurumae 35, Himiko, Senga gigana and Daehak I were resistant, whereas Hokowase, Instiate Z4, Juspa, Puget beauty and Marshall were susceptible to the fungus with artificial inoculation.

• The Korean Journal of Pesticide Science
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• v.5 no.2
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• pp.26-32
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• 2001

[ ${\alpha},{\beta}$ ]-Unsaturated carboxamides 12 with trifluromethylated dihydro-1,4-dithiins were synthesized for the purpose of development of new agrochemical fungicide. Chlorination of trifluoromethylated ${\beta}$-ketoester 4 followed by tile reaction with 1,2-ethanedithiol gave intermediate 1,4-dithiane 9. Without purification of 9 substitution of hydroxy by chlorine followed by dehydrochlorination in the presence of triethylamine afforded trifluoromethylated dihydro-1,4-dithiin ethyl ester 7. Activation of the hydroxy of the carboxylic acid 10 obtained from the hydrolysis of 7 and then reacted with various amines gave the corresponding trifluoromethylated dihydro-1,4-dithiin carboxamides. Antifungal screening (in vivo) against typical plant diseases, Rice Blast, Rice Sheath Blight, Cucumber Gray Mold, Tomato Late Blight, Wheat Leaf Rust, and Barley Powdery Mildew of the synthesized compounds was carried out. As a result, most of the compounds shlowed weak antifungal activities and some compounds in which isopropyl group was substituted in meta of the phenyl showed antifungal activity (99%) at 250 ppm against the disease Wheat Leaf Rust.