• The Korean Journal of Pesticide Science
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• v.4 no.1
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• pp.64-70
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• 2000

Control effects of phosphorous acid were investigated on three diseases. For Phytophthora blight of red pepper, protective and curative effects of phosphorous acid at the concentration of $1,408{\mu}g$ a. i./mL were 91.0% and 80.0%, respectively. In case of late blight of tomato, caused by Phytophthora infestans, protective and curative effects were 63.4% and 13.0% at the same concentration, respectively. However, the protective and curative effects of phosphorous acid increased by decreasing inoculum density of Phytophthora infestans. The protective effects of phosphorous acid on control of Phytophthora blight of red pepper was persisted for 4 days with high control efficacy (94.0%). The protective and curative effects of phosphorous acid ($1,408{\mu}g$ a. i./mL) on cucumber downy mildew were 82.0% and 62.0% respectively. The foliar application of phosphorous acid also promoted shoot growth and fresh weight of red pepper.

• The Korean Journal of Pesticide Science
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• v.11 no.4
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• pp.313-319
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• 2007

Nine plant growth regulators (PGRs) were tested for in vivo antifungal activities against on rice blast. They showed higher in vivo antifungal activities when they were applied on rice plants by soil drench rather than foliar spray. Except for 2,4-D at $500\;{\mu}g\;mL^{-1}$, the others showed a very low or no activity against the disease in foliar spray applications. In contrast, 2,4-D, indole butyric acid (IBA) and triiodobenzoic acid, at $500\;{\mu}g\;mL^{-1}$, showed control values of 98.9, 97.8 and 88.9% in soil drench applications. Furthermore, the control activity of IBA was dependent on its concentration against rice blast; IBA suppressed the development of rice blast by 71.7% at $125\;{\mu}g\;mL^{-1}$ and 85.8% at $250\;{\mu}g\;mL^{-1}$. IBA also controlled the development of rice blast on adult plants by 63.9% at a dosage of 2.56 kg/10a. The results revealed that IBA has a good activity against rice blast when it is applied by soil drench.

• Horticultural Science & Technology
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• v.29 no.6
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• pp.610-616
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• 2011

Clubroot disease caused by Plasmodiophora brassicae, induces damage to cruciferous vegetables worldwide. For control of the disease, many CR (clubroot resistant) $F_1$ hybrid cultivars of Chinese cabbage have been bred and released in Korea. In this study, we determined the race of 10 field isolates of P. brassicae collected from ten regions in Korea using Williams' differential varieties and investigated the degree of resistance of 25 commercial CR cultivars of Chinese cabbage to the isolates. The clubroot pathogens were assigned into two (HS and YC), two (HN1 and HN2), two (DJ and SS) and four (GS, GN, JS, and PC) isolates for race 2, race 4, race 5, race 9, respectively. All CR cultivars showed similar response, resistant or susceptible, to each isolate and the P. brassicae isolates were divided into two groups. Among them, the DJ, GS, GN, HS, and JS isolates could not infect the CR cultivars. In contrast, the SS, HN1, HN2, PC, and YC isolates caused severe clubroot disease on the CR cultivars like susceptible cultivars. Even though they belong to the same race, the CR cultivars showed a different response to the pathogens. The results suggest that the breakdown of CR in Chinese cabbage has already occurred in cultivation areas of Korea and resistance source introduced in CR cultivars may be very limited. In addition, it is likely that resistance genes of Williams' differential varieties to P. brassicae are different from the gene of CR cultivars of Chinese cabbage used in the study.

• 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.6 no.2
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• pp.87-95
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• 2002

Disease control activities of the methanol extracts from 27 plant species were investigated against six plant diseases such as rice blast, rice sheath blight, tomato gray mold, tomato late blight, wheat leaf rust and barley powdery mildew. The extracts of Humulus japonicus, Hosta longipes, Liriope platyphylla, and Astragalus membranaceus exhibited a great in vivo control activity against rice blast. Similarly, the extracts of Commelina communis and A. membranaceus were highly active on tomato gray mold and barley powdery mildew, respectively. The extracts of H. longipes, L. platyphylla, Solanum nigrum and A. membranaceus showed especially high disease control activity against wheat leaf rust, and then were selected for further tests such as protective, curative, systemic, and lasting activity against wheat leaf rust. The extracts of L. platyphylla and S. nigrum were strong protectant, and that of A. membranaceus possessed both a preventive activity and a curative activity. Systemic disease control by the selected four plant extracts was investigated by examing translaminar activity from leaf-under-surface to leaf-upper-surface and systemic activity by leaf-to-Ieaf movement. All extracts strongly controlled wheat leaf rust by translaminar movement, but hardly controlled the disease by leaf-to-leaf movement. Good lasting activity was also observed against wheat leaf rust from all of the tested extracts. Especially, disease control experiments on wheat seedlings sprayed with the extracts of S. nigrum or H. longipes 7 days prior to inoculation represented control value over 95%. These results suggest that methanol extracts of H. longipes, L. platyphylla, S. nigrum, and A. membranaceus, especially S. nigrum, would potently control wheat leaf rust caused by Puccinia recondita in the fields.

• Applied Biological Chemistry
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• v.44 no.2
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• pp.109-115
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• 2001

The foliar uptake of dimethomoiph induced by several nonionic surfactants was measured in order to study the correlations between the uptake rate of dimethomorph and the fungicidal activity to cucumber downy mildew. Dimethomorph was not absorbed in cucumber leaf in the absence of activator surfactant. And the curative effect of dimethomoiph WP to cucumber downy mildew was very low under the concentration of 250 ${\mu}g/ml$. But dimethomorph uptake was remarkably enhanced by addition of nonionic surfactants, such as polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, and polyoxyethylene stearyl ether. And the curative effect to cucumber downy mildew was enhanced with proportion to uptake rate of dimethomorph. The protective effect to cucumber downy mildew, however, tends to decrease with the increase of foliar uptake of dimethomorph. The uptake rate of dimethomorph to cucumber leaf was proportional to the content of polyoxyethylene cetyl ether in formulation, but was decreased with dilution.

• Applied Biological Chemistry
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• v.51 no.2
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• pp.108-113
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• 2008

Azoxystrobin applied by aqueous WP suspension 50 mg/l was slightly absorbed into cucumber leaf in the absence of activator surfactant 24 h after spraying, but was increased to 25.7% by adding polyoxyethylene monohexadecyl ether (12 moles of ethylene oxide, CE-12) 500 mg/l. Only 4.1% of kresoxim-methyl WDG 100 mg/l in the absence of surfactant was absorbed into cucumber leaf 24 h after spraying, but was increased to 58.0% by adding polyoxyethylene monooctadecyl ether (14 moles of ethylene oxide, SE-14) 1,000 mg/l. The effect of CE-12 500 mg/l on foliar uptake of kresoxim-methyl at 50 mg/l was twice bigger than on azoxystrobin. Fungicidal activity of azoxystrobin WP against cucumber powdery mildew was marginally increased by adding surfactants to facilitate foliar uptake of azoxystrobin, so that the further increase of azoxystrobin uptake into cucumber plant by the addition of adjuvant was not a practical mean for enhancing the formulation efficacy in view of fungicidal activity. It was not possible for kresoxim-methyl to assess the adjuvant effect on the fungicidal activity in a greenhouse trial due to the vapor effect of active ingredient.

• Microbiology and Biotechnology Letters
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• v.31 no.1
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• pp.25-31
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• 2003

Delftia acidovorans 51-A isolated from river water degrades aniline. In order to clone genes involved in aniline degradation, transposon Tn5-B20 was inserted into the strain 51-A to generate a mutant strain 10-4-2 that cannot utilize aniline as a carbon source. The mutant strain was not an auxotroph but could not degrade aniline. Southern hybridization analysis indicated that the transposon was inserted into the mutant bacterial DNA as a single copy. Flanking DNA fragment of Tn5-B2O insertion was cloned and sequenced. DNA sequence analysis revealed three ORFs encoding TdnQ, TdnT, and TdnA 1 that arc responsible for catechol formation from aniline through oxidative deamination. The analysis also confirmed that Tn5-B2O was inserted at the immediate downstream of tdnA1. The result suggests that the transposon insertion behind tdirA1 disrupted the pathway of the catechol formation from aniline, resulting in the mutant phenotype, which cannot degrade aniline. A large plasmid over 100-kb in size was detected from D. acidovorans 51-A and Southern hybridization analysis with Tn5-B2O probe showed that the transposon was inserted on the plasmid named pTDN51. Our results indicated that the tdn genes on pTDN51 of D. acidovorans 51-A are involved in aniline degradation.

• The Korean Journal of Pesticide Science
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• v.10 no.1
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• pp.36-42
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• 2006

For the effective control of pepper anthracnose, in vitro antifungal activities of 13 commercial fungicides were tested on spore germination, mycelial growth, and sporulation of Colletotrichum gloeosporioides, anthracnose fungus. Among them, captan, chlorothalonil, dithianon, fluazinam and folpet completely inhibited the spore germination of C. gloeosporioides at the concentration of 0.8 ${\mu}g/ml$. They were followed by mancozeb and propineb, showing more than 80% inhibition of spore germination at 20 ${\mu}g/ml$. The mycelial growth of C. gloeosporioides was strongly inhibited by fluazinam and nuarimol. Except for nuarimol, most of the fungicides represented more antifungal activity on the spore germination than the mycelial growth of C. gloeosporioides. Azoxystrobin and metominostrobin, Strobilurin fungicides, were only moderately active against the spore germination and the mycelial growth of C. gloeosporioides, but they were effective antisporulant against C. gloeosporioides. From these results, control of pepper anthracnose will have achieved by preventive spray of the commercial fungicides.

• The Korean Journal of Pesticide Science
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• v.3 no.3
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• pp.37-44
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• 1999

Two sulphamide (dichlofluanid and tolylfluanid) and three dicarboximide fungicides (iprodione, vinclozolin, procymidone) were used to investigate the correlation between in vitro antifungal activities and in vivo disease controlling activities against Botrytis cinerea, a causal agent of tomato gray mold and to develop efficient in vitro assays. They controlled effectively the development of tomato gray mold disease in vivo and their controlling activities were similar one another. However, several in vitro assays revealed that their in vitro antifungal activities were quite different between sulphamide and dicarboximide fungicides; the formers showed stronger inhibition activities for spore germination than the latters, whereas the formers inhibited mycelial growth less severely than the latters. The results indicate that the fungicides having different modes of action can show different in vitro antifungal activities according to in vitro assays, even if they have similar in vivo disease controlling activities. On the other hand, two rapid and efficient in vitro assays named Microtiter plate methods I (MPM I) and II (MPM II) were developed for the evaluation of fungicides for inhibitory activities against spore germination and mycelial growth of B. cinerea, respectively. The antifungal activities of five fungicides of two chemical groups in MPM I and II were correlated with the inhibitory activities against spore germination and mycelial growth using solid media, respectively.