• Research in Plant Disease
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• v.17 no.2
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• pp.129-135
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• 2011

Chitosan is a linear polysaccharide composed of randomly distributed ${\ss}$-(1-4)-linked D-glucosamine and Nacetyl-D-glucosamine. There have been many reports on the induced systemic resistance and in vivo antifungal activities of higher molecular weight chitosans with molecular weights over 3,000 amu (atomatic mass unit), but there are few papers on in vivo antifungal activities of low molecular weight chitosans (oligochitosans) with molecular weights less than 3,000 amu. In our study, an oligochitosan sample (320.3,000 amu) showed a potent 1-day protective activity with control values more than 94% at concentrations of 500 and 1,000 ${\mu}g$/ml especially against tomato late blight caused by Phytophthora infestans under growth chamber conditions. It also displayed a moderate 1-day protective activity with control values of 67.89% at concentrations of 500 and 1,000 ${\mu}g$/ml against wheat leaf rust and red pepper anthracnose. On the other hand, it showed a 16-hr curative activity against red pepper anthracnose, but not against tomato late blight and wheat leaf rust. In field experiments, oligochitosan effectively suppressed the development of late blight on potato and tomato plants with control values of 72% and 48%, respectively. The results strongly indicate that oligochitosan can be used as an eco-friendly organic material for the control of late blight on tomato and potato plants.

• Journal of Plant Biotechnology
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• v.29 no.2
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• pp.93-98
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• 2002

A VP6 fragments was subcloned with BamHI in the binary pMBP-1 vector under Califlower Mosaic Virus (CaMV) 355 promoter and neomycin phosphotransferase II (npt II) gene. The recombinant binary vector was mobilized into Agrobacterium-tumefaciens LBA4404 by the freeze-thaw method and potato (Solanum tubensum L. cv Desiree) was transformed by modified leaf-disc cocultivation. Shoots were induced on MS medium with 0.01 mg/L NAA, 0.1 mg/L GA$_3$, 2.0 mg/L Zeatin, 100.0 mg/L kanamycin, 500.0 mg/L carbenicillin. In order to identify the copy number of VP6 into potato plant, total genomic DNA was isolated from transgenic potato and analysed by Southern blotting. Genomic DNA and total mRNA analysis demonstrated the incorporation of the foreign gene into the potato genome, as well as their transcription.

• Weed & Turfgrass Science
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• v.2 no.3
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• pp.306-311
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• 2013

Pythium blight occurred by Pythium aphanidermatum on chewing fescue cv. "Jamestowm II" from early June, 2010 and 2011 at the test field in Daegu University in Gyeongbuk Province, Korea. Disease symptoms on the turfgrass were leaf blights dying from the leaf tip and root rot, which appeared patches of brown to dark brown color or gray brown color in the field. The pathogens (40-1 isolate) of Pythium blight was isolated from the diseased leaf and crown tissue and cultured on potato-dextrose agar (PDA) for identification. Lobulate sporangia were inflated, complex structures, and filamentous sporangia were usually indistinguishable from vegetative hyphae. Sequences of ribosomal RNA gene of the fungus were homologous with similarity of 100% to those of P. aphanidermatum isolates in GenBank database. Pathogenicity was also confirmed on the chewing fescue, creeping betgrass and Kentucky bluegrass by Koch's postulates. This is the first report of Pythium blight on chewing fescue caused by P. aphanidermatum in Korea.

• Research in Plant Disease
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• v.29 no.3
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• pp.251-257
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• 2023

In order to examine the pathogenicity of Alternaria dauci, the causal agent of carrot leaf blight, it is necessary to standardize sporulation conditions to ensure the optimal quantity and quality of spore inoculum. Therefore, in this study, the effects of the growth medium, aeration treatment, and UV treatment with 12-hr photoperiod on the sporulation of A. dauci KACC42997 were investigated. A. dauci KACC42997 was pre-cultured for 7 days in a potato dextrose agar medium at 25℃ in the dark condition. When the pre-culture, after removing aerial mycelia, was re-incubated for 5 days, with simultaneous aeration treatment and 12-hr cycle UV treatment at 20℃, the largest number of spores was produced. One hundred seventy isolates of A. dauci were isolated from major carrot growing regions such as Pyeongchang, Gumi and Jeju and tested for sporulation under the conditions established in this study. Except for 20 strains, all strains produced spores. Statistically significant differences in the extent of sporulation were found among local populations of A. dauci isolates, but no difference was observed in their pathogenicity on carrots.

• Journal of the Korean Society of Tobacco Science
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• v.31 no.2
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• pp.69-74
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• 2009

Potato Virus Y (PVY), PVY-vein necrosis strain, causes severe damage at growth, yield and leaf quality on flue-cured tobacco in Korea. The development of PVY resistant flue-cured varieties without quality deterioration is therefore urgently desired. The flue-cured tobacco, KF120 (Korea Flue-cured 120), was a male-sterile (ms) $F_1$ hybrid derived from the cross between msKF117 and KF0007-7. msKF117 was developed from the cross of NC82 with N. africana and KF0007-7 was developed from the cross of KF117 with NC82. The agronomic characteristics and disease resistance of KF120 was evaluated during 2006-2007 field performance test. It showed better growth characteristics and yield performance than standard cultivar KF109. It had 2 more leaves per plant, flowered 2 days later than KF109. The yield of cured leaf of KF120 was increased by about 5% compared to KF109. The chemical composition and physical properties of the cured leaf of KF120 were as much acceptable as those of KF109. KF120 showed high resistance to PVY compared to KF109. It showed a similar mode of resistance to bacterial wilt and black shank as was found in KF109.

• Mycobiology
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• v.31 no.3
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• pp.179-182
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• 2003

A total of 187 endophytic fungi were isolated from 11 plant species, which were collected from 11 locations in Korea. Their antifungal activities were screened in vivo by antifungal bioassays after they were cultured in potato dextrose broth and rice solid media. Antifungal activity against plant pathogenic fungi such as Magnaporthe grisea(rice blast), Corticium sasaki(rice sheath blight), Botrytis cinerea(tomato gray mold), Phytophthora infestans(tomato late blight), Puccinia recondita(wheat leaf rust), and Blumeria graminis f. sp. hordei(barley powdery mildew) was determined in vivo by observing the inhibition of plant disease development. Twenty(11.7%) endophytic fungi fermentation broths were able to control, by more than 90%, at least one of the six plant diseases tested. Among 187 liquid broths, the F0010 strain isolated from Abies holophylla had the most potent disease control activity; it showed control values of more than 90% against five plant diseases, except for tomato late blight. On the other hand, fourteen(7.5%) solid culture extracts exhibited potent disease control values of more than 90% against one of six plant diseases. The screening results of this study strongly suggested that metabolites of plant endophytic fungi could be good potential sources for screening programs of bioactive natural products.

• Journal of the Korean Society of Food Culture
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• v.24 no.2
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• pp.146-154
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• 2009

This study was conducted to investigate the vegetable eating behaviors and preferences of elementary school students by stage of change for vegetable intake. The subjects consisted of 191 fourth and fifth grade elementary school students from Gyeonggi province. The stage of change for vegetable intake was categorized into three groups: precontemplation (PC, 18.4%), preparation (P, 43.5%), and action/maintenance (A&M, 48.2%). The trend to eat a variety of foods was more distinctive as the students went from the PC to the A&M stage. The stage of change for vegetable intake was closely related with the kimchi-eating pattern of the students. The A&M group ate more vegetables than the PC group because they liked vegetables and/or wanted to prevent disease. The PC group had a lower tendency to follow recommendations for vegetable eating than the P and A&M groups. The PC group also had an incorrect notion that low vegetable consumption over an extended time would not have a big impact on their health. The vegetables of high preference for the elementary school students were potato, sweet potato, lettuce, radish, perilla leaf, cucumber, and cabbage. The vegetables of low preference were spinach, onion, balloon flower, and green pepper. The PC group had lower preferences for most vegetables than the P and A&M groups. Therefore, careful nutrition education is necessary especially for students in the PC group in order to explain the positive effects of vegetable intake and negative effects of an unbalanced diet. It is also necessary to survey students' tastes consistently and to develop recipes that encourage them to consume more vegetables agreeably.

• Research in Plant Disease
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• v.22 no.2
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• pp.116-121
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• 2016

In 2015, stem blight of Rubus crataegifolius was observed in Pohang, Korea. The symptoms began as dark red spots in the stem, which led to stem blight, then leaf blight, and eventually resulted in death. A fungal isolate was obtained from a symptomatic stem and incubated on a potato dextrose agar plate. The isolated fungus produced white, cloudy mycelia turned black in 3 days. Based on the morphological characteristics, the causal fungus was assumed to be Botryosphaeria sp. A pathogenicity test was conducted according to Koch's postulates. To identify the causal agent, the combined sequence of the internal transcribed spacer, ${\beta}$-tubulin, and translation elongation factor $1{\alpha}$ genes were used for phylogenetic analysis. Approximately 1,200 bp of the combined sequence clearly suggested that the isolated pathogen was Botryosphaeria parva. This is the first report on stem blight in R. crataegifolius caused by B. parva in Korea.

• Research in Plant Disease
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• v.10 no.2
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• pp.130-134
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• 2004

The pathogenesity of 25 isolates of Colletotrichum gloeosporioides from apple, 42 isolates from pepper, 5 isolates from jujube, 8 isolates from persimmon was evaluated to know transmission to strawberry from other infected plants. Followings are the results. Colony morphology and spore size on potato dextrose agar was similar. When each isolate was inoculated on leaf and petiole of strawberry, isolates from persimmon was the most pathogenic. Five isolates, one pathogenic isolate per each host, were evaluated in simulated field condition under natural rainfall for their natural infectivity. All isolates infected strawberry in field condition, so C. gloeosporioides from other hosts are potential inoculum source of strawberry anthracnose.

• Research in Plant Disease
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• v.8 no.1
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• pp.50-54
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• 2002

A total of 55 Colletotrichum isolates from strawberry plants with anthracnose symptoms(crown rot) were inhibited in mycelial growth on potato-dextrose agar(PDA) amended with fungicides in variable degrees depending on the chemicals used, especially showing no growth on PDA with 1 mg/m/tricyclazole. However, in the detached leaf test by treating chemicals before or after inoculation of Colletotrichum sp., tricyclazole was little effective in controlling symptom development; instead azoxystrobin, which had low in vitro inhibition of mycelial growth, inhibited strongly the symptom development. Some chemicals were tested for the control of strawberry crown rot in greenhouse using three methods, sprays soil drenching and plant dipping. No or little control effect were made by chemical spray and soil drenching, but plant dipping in chemical solution, especially azoxystrobin: reduced crown rot development by about 50% in the greenhouse suggesting that the azoxystrobin treatment may be an effective control method of the crown rot of strawberry. No differences in the control efficacy were noted according to the dipping time and chemical concentration of azoxystrobin not less than 10 min and 250 mg/m/, respectively.