• The Plant Pathology Journal
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• v.23 no.4
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• pp.308-313
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• 2007

A survey of the occurrence of abiotic diseases on kiwifruit (Actinidia deliciosa) trees was conducted at sixty-two kiwifruit orchards in twenty-one locations of Jeonnam and Jeju Provinces in Korea during the 2007 growing season. Various kinds of abiotic diseases were detected on the kiwifruit trees. Malformed fruits caused by incomplete pollination were commonly observed among the normally growing fruits on almost all of the kiwifruit trees examined. Fruits imbued with wire rust, fruits scratched or girdled by the wire and fruits injured by sunscald occurred in all of the examined orchards. Abnormal growth of girdled branches by the fence wire, dead trees killed by excessive soil moisture due to poor draining and leaf chlorosis by nutrient deficiencies were found in some orchards. Leaf spotting by herbicide and leaf scorch or blight by excessively high temperature were observed. Leaf blight on young shoots by late frost and bark split on trunks by freeze occurred in several open-field orchards. Flooding and strong wind damages by attack of typhoon 'Nari' were also found during the survey period. Cup-shaped leaves frequently occurred on young shoots in early spring and the incidence of the syndrome tends to increase annually in recent years, which are not etiologically defined until now.

• Applied Biological Chemistry
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• v.45 no.3
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• pp.157-161
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• 2002

New 2-benzoylimino-1,3-oxathile derivatives 3 were synthesized and tested their fungicidal activities for the development of new agrochemical fungicide. Reaction of ${\gamma}-chloro-{\beta}-keto$ anilide derivative 5 with potassium thiocyanate followed by the treatment of acid catalyst gave cyclyzed 2-imino-1,3-oxathiole 3. New compound 3 reacted with benzoyl· chlorides to afford the corresponding 2-benzoylimino-1,3-oxathiole derivatives 7. Antifungal screening (in vivo) of the synthesized compounds against typical plant diseases, which include rice blast, rice sheath blight, cucumber gray mold, tomato late blight, wheat leaf rust, and barley powdery mildew, was carried out. No significant fungicidal activities were shown of the synthesized compounds at 100 mg/l.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.359-366
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• 2006

The protective effect of kresoxim-methyl was investigated on 6 important plant diseases, and the vapour effect of it did on barley and cucumber powdery mildews, respectively. With 2.0 ${\mu}g\;mL^{-1}$ of kresoxim-methyl, its high activities against wheat leaf rust and barley powdery mildew were showed such as 92 and 100%, while activities were very low against rice sheath blight, tomato gray mold, and tomato late blight. In vapour phase control activity of kresoxim-methyl against barley powdery mildew was positively correlated with the applied concentrations, except for azoxystrobin and metominostrobin. With 200 ${\mu}g\;L^{-1}$, its control value was 71.9%. When 1000 ${\mu}g\;m^{-3}$ of kresoxim-methyl in vapour phase was applied on 4 plants of cucumber in a vinyl chamber, 51.1% of control value on kresoxim-methyl-treated cucumber was showed 7 days after the application.

• The Plant Pathology Journal
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• v.26 no.4
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• pp.360-366
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• 2010

In the course of a searhing environmental friendly antifungal compounds, we found that mixture of methyl esters of fatty acids obtained from soybean oil had potent control efficacy against barley powdery mildew (Blumeria graminis f. sp. hordei). In this study, ten alkyl fatty acid esters (AFAEs) were tested for in vivo antifungal activity against five plant diseases such as rice blast, rice sheath blight, tomato gray mold, tomato late blight and barley powdery mildew. Some AFAEs showed the most control efficacy against barley powdery mildew among the tested plant diseases. By 5-hr protective and 1-day curative applications, six AFAEs ($3,000\;{\mu}g/ml$), including methyl and ethyl palmitates, methyl and ethyl oleates, methyl linoleate, and methyl linolenate demonstrated both curative and protective activities against barley powdery mildew. In contrary, methyl laurate strongly controlled the development of powdery mildew on barley plants by curative treatment at a concentration of $333\;{\mu}g/ml$, but did not show protective activity even at $3,000\;{\mu}g/ml$. Under greenhouse conditions, the seven AFAEs ($1,000\;{\mu}g/ml$) except for methyl and ethyl stearates, and methyl caprylate also effectively controlled cucumber powdery mildew caused by Podosphaera xanthii. Among them, methyl and ethyl palmitates ($333\;{\mu}g/ml$) represented the most control activity of more than 68% against the disease. The results are the first report on the antifungal activity of methyl and ethyl esters of fatty acids against plant pathogenic fungi.

• The Korean Journal of Pesticide Science
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• v.5 no.3
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• pp.26-35
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• 2001

In order to search potent antifungal substances from domestic plants, 40 plants cultivated in Korea were collected. After extracting with methanol (MeOH) and concentrating to dryness, the MeOH extracts were screened for in vivo antifungal activity against six plant diseases at a concentration of $2000{\mu}g/mL$. Fourteen extracts showed disease-controlling activity more than 90% against at least one of the 6 plant diseases tested; eight, seven, and three extracts controlled more than 90% the development of rice blast, tomato late blight, and wheat leaf rust, respectively. However, none of the extracts exhibited in vivo antifungal activity more than 90% against rice sheath blight, tomato gray mold, and barley powdery mildew. From the MeOH extracts of Angelica gigas and A. dahurica showing potent controlling activity against rice blast, 1 and 2 antifungal substances, respectively, were isolated by solvent partitioning and column chromatography. The three compounds were identified to be coumarins, namely, decursin, imperatorin, and isoimperatorin, by mass spectrometry and NMR spectroscopy. They were examined for in vitro and in vivo antifungal activities together with umbelliferone (7-bydroxycournarin) and scopoletin (6-methoxy-7-hydroxycoumarin) containing a free hydroxyl group at position 7 to investigate the structure-activity relationship. In vitro, most of 50% growth inhibitory concentrations ($IC_{50}$) were over $200{\mu}g/mL$, indicating that they have relatively weak antifungal activity. The antifungal activity of decursin and scopoletin, containing cyclic alkoxy groups instead of free hydroxyl group at position 7, was stronger than umbelliferone and scopoletin. Especially, decursin and imperatorin showed potent antifungal activities against Pythium ultimum and Magnaporthe grisea, respectively, with $IC_{50}$ values less than $25{\mu}g/mL$. In vivo, decursin and imperatorin showed potent antifungal activity against rice blast, whereas other coumarins hardly controlled the development of 6 plant diseases tested. These results suggest that the antifungal activity of 7-hydroxycoumarin derivative is substantially increased when the hydroxyl group at position 7 is protected by a stable cyclic alkoxy grouping.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.4
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• pp.339-349
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• 2021

In recent years, the occurrence of bacterial diseases of soybean has been increasing due to the continuous rise in spring temperature and the humid weather as a result of rain concentrated at the middle and late stages of crop growth. The resulting severe economic damage is also a concern. Unfortunately, there are no precise data on the occurrence and damage to lay the foundation for bacterial disease control in soybean in the Chungbuk Province. Therefore, the present study investigated the occurrence of major bacterial diseases, namely bacterial pustules, bacterial blight, and wildfire, in different soybean varieties in 410 fields in the Chungbuk Province in 2017. The incidence rate of bacterial pustules in the affected fields was 76.6%, and the incidence rate of infected plants was 29.3%. The incidence rate of bacterial blight in the affected fields was 13.9%, and the incidence rate of infected plants was 4.6%. The incidence rate of wildfire in the affected fields was 23.2%, and the incidence rate of infected plants was 10.1%. The overall incidence rate of bacterial diseases in the soybean fields where the diseases originated was 37.9% for bacterial pustules, 21.0% for bacterial blight, and 25.0% for wildfire, indicating that the disease incidence rate in fields where the disease originated was generally high. Among different varieties, the incidence rate of bacterial pustules was the highest in sprout soybean (88.9%), followed by Seoritae (84.0%) and Daewon (81.2%). The incidence rate of bacterial blight was the highest in the Daewon (19.6%), followed by Seoritae (15.2%) and sprout soybean (12.5%). The incidence rate of wildfire was the highest in sprout soybean (25.0%), followed by Daewon (24.7%) and Seoritae (5.4%). Meanwhile, in Uram, the incidence rate of bacterial pustules (7.1%) was the lowest, and this variety was not affected by bacterial blight or wildfire.

• Horticultural Science & Technology
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• v.30 no.5
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• pp.557-567
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• 2012

This study was conducted to achieve basal information for the development of tomato cultivars with disease resistances through marker-assisted backcross (MAB). Ten inbred lines with TYLCV, late blight, bacterial wilt, or powdery mildew resistance and four adapted inbred lines with superior horticultural traits were collected, which can be useful as the donor parents and recurrent parents in MAB, respectively. Inbred lines collected were evaluated by molecular markers and bioassay for confirming their disease resistances. To develop DNA markers for selecting recurrent parent genome (background selection) in MAB, a total of 108 simple sequence repeat (SSR) primer sets (nine per chromosome at average) were selected from the tomato reference genetic maps posted on SOL Genomics Network. Genetic similarity and relationships among the inbred lines were assessed using a total of 303 polymorphic SSR markers. Similarity coefficient ranged from 0.33 to 0.80; the highest similarity coefficient (0.80) was found between bacterial wilt-resistant donor lines '10BA333' and '10BA424', and the lowest (0.33) between a late blight resistant-wild species L3708 (S. pimpinelliforium L.) and '10BA424'. UPGMA analysis grouped the inbred lines into three clusters based on the similarity coefficient 0.58. Most of the donor lines of the same resistance were closely related, indicating the possibility that these lines were developed using a common resistance source. Parent combinations (donor parent ${\times}$ recurrent parent) showing appropriate levels of genetic distance and SSR marker polymorphism for MAB were selected based on the dendrogram. These combinations included 'TYR1' ${\times}$ 'RPL1' for TYLCV, '10BA333' or '10BA424' ${\times}$ 'RPL2' for bacterial wilt, and 'KNU12' ${\times}$ 'AV107-4' or 'RPL2' for powdery mildew. For late blight, the wild species resistant line 'L3708' was distantly related to all recurrent parental lines, and a suitable parent combination for MAB was 'L3708' ${\times}$ 'AV107-4', which showed a similarity coefficient of 0.41 and 45 polymorphic SSR markers.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.1
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• pp.25-31
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• 2005

A soil bacterium, Bacillus subtilis HJ927, exhibiting strong antagonistic property against pathogenic fungi was isolated from pepper fields infested with Phytophthora capsici. Pepper plants inoculated with P. capsici revealed severe root mortality while plants co-inoculated with B. subtilis HJ927 and P. capsici showed drastically reduced root mortality. Low molecular weight substances released by B. subtilis HJ927 mediated the plant protective effect. The anti-fungal compounds released by B. subtilis HJ927 were identified as 3-methylbutyric acid, 2-methylbutyric acid, and methyl 2-hydroxy, 3-phenylpropanoate by high-performance liquid chromatography and gas chromatography-mass spectrometry. In addition to these compounds, B. subtilis HJ927 also produced ${\beta}$-1,3-glucanase, a hydrolytic enzyme implicated in antifungal activity.

• The Korean Journal of Pesticide Science
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• v.10 no.2
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• pp.149-152
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• 2006

Construction of focused library of 2-benzylimino-1,3-thiazolines 7 through molecular modification of 3-alkyl-2-phenylimino-1,3-thiazolines 1 which showed selective fungicidal activity against rice blast and their fungitoxic activity against 6 kinds of typical plant diseases was described. Fifty four compounds of focused library of 2-benzylimino-1,3-thiazolines 7 were synthesized from the reaction of the corresponding $\gamma$-chloroacetoacetanilides 6 with N-benzyl thioureas 5 by parallel synthetic methodology. As results of fungicidal screening against the typical plant diseases, twenty eight kinds of 7 at 100 ${\mu}g$ $mL^{-1}$ showed the control value over 50% against tomato late blight.

• The Korean Journal of Pesticide Science
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• v.7 no.1
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• pp.25-31
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• 2003

Changes of control effect of metalaxyl to potato late blight caused by Phytophthora infestans were examined in potato fields in 2001 and 2002. Control efficacy of metalaxyl was similar to those of dimethomorph and ethaboxam. About 4.9% of the fungal isolates exanlined in 2001 were resistant, 87.8% were intermediate, and 7.3% were sensitive to metalaxyl. Among the isolates collected in 2002, 20.1 % were resistant, 75.5% were intermediate, and 4.3% were sensitive to the chemical. However, most of resistant isolates were isolated from Pyongchanggun Hoenggae area. Eighty eight isolates collected in 2001 were all A1 mating type, while both A1 and A2 mating types were found in 2002. About 85.6% of the isolates collected in 2002 were A1 mating type, but all the rest (A2 mating type) was isolated from Hoenggae area. Increased control efficacy of metalaxyl to potato late blight might be caused by the increase of moderately resistant and sensitive isolates with decreasing the resistant isolate, and the decreased population of A2 mating type which is resistant to metalaxyl.