• Research in Plant Disease
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• v.24 no.2
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• pp.132-137
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• 2018

Melanose caused by Diaporthe citri is a serious disease on yuzu fruits. Moisture is the most important to infect after the pycnidiospores are released. In order to understand how dryness and moisture interruption affect on germination, the conidial suspensions on slide glass were dried for 0-48 h. For the moisture interruption experiment, moisture was supplied for 10 h then interrupted for 0-6 h depending on the treatments. Germinations on the treatments with longer than 15 h of dryness were less than 10%. And those with longer than 3 h of moisture interruption were less than 30%. Compared with other fungal phytopathogens, D. citri was xero-sensitive. Germination on yuzu feel medium was measured under 15, 20, 25, 30, $35^{\circ}C$ with 3, 6, 9, 12, 15, 18, and 24 h of wetness. The minimum wetness periods achieving 10% and 50% germinations were 4.5 and 13 h, and the optimum temperatures were $29.1^{\circ}C$ and $29.2^{\circ}C$, respectively. From the yuzu medium study, the regression equations to be required wetness period achieving 10% and 50% germinations on various temperatures were $Wh_{50%}=0.1093{\times}T^2-6.3762{\times}+106.08$ and $Wh_{10%}=0.082{\times}T^2-4.8025{\times}T+74.861$.

• Korean Journal of Plant Resources
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• v.4 no.2
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• pp.51-58
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• 1991

With the soil samples collected from 33 locations in Kwangju area, the physiochemical properties of soil and soil microorganisms have been studied and the results of'the analysis were as follows ;1 . Tlle temperatilre, pH, moisture and organic matter of sampling s'tes were measured in the range of 21.O~28.O$^{\circ}C$, 4.0"6.6, 2.1"24.0% and 2.8~22.0% respectively.and that showed wide range distribution in moisture and organio mattrr particulary.and averase was 24.$^{\circ}C$ of temperature, 4.9 of pH, 11.9% of moisture and 8.9% of'organic matter.2. The general bacterial number, cellulolytic bacterial number, general fungal number and cellulolytic fungal number were measured in tile range of 23$\times$10$^{[-995]}$ _1548x10$^{[-995]}$ , 8.0$\times$10$^{[-995]}$ ~412.0$\times$10$^{[-995]}$ , 0.3$\times$10$^{[-994]}$ ~56.4$\times$10$^{[-994]}$ and 0.Ix10$^{[-994]}$ ~17.2x10$^{[-994]}$ , respectivelyand average was 378.4$\times$10$^{[-995]}$ of general bacteria, 102.5$\times$10$^{[-995]}$ of cellulolytic bacteria.13.OX10$^{[-994]}$ of general fungi and 4.3$\times$10$^{[-994]}$ of cellulolytic fungi.tic fungi.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.609-614
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• 1997

C-MH(Choline salt of maleic hydrazide, 39％) has been applied on peanut(Arachis hypogaea L.) plant in 1994∼1995 on three different times of 24 days after flowering (DAF), 28 DAF and 31 DAF and on three different levels of 0.2, 0.1. 0.067％, respectively. Main stem length was noticeably retarded by 38∼44％ compared to that of non-treatment. Branch numbers were not changed by C-MH treatments. Ratio of flowering inhibition was 38％ in 0.2％ concentration and 22％ in 0.067％ at 28 days after flowering treatment compared to that of control. Ratio of pure seed was slightly enhanced by 3％ in 28 DAF treatments. Yield productivity was increased by 7％ in 0.1％, at 28 DAF treatment compared to that of non-treatment (3.2MT /ha).

• Journal of Bio-Environment Control
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• v.15 no.4
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• pp.417-420
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• 2006

To investigated the dormancy of chicory (Cichorium intybus L.) for production of high quality rootstocks, growth characteristics and abscisic acid (ABA) contents was conducted. The accumulation hours below $5^{\circ}C$ in field was increased slowly from October 7 to December 3, but there after increased largely. The rootstock weights was increased from the end of October to December 3, there after was not changed to December 3. ABA contents within the rootstock was not changed from October 7 to December 3, and there was suddenly increased for two weeks to December 24. As results of the sudden changed date of accumulation hours below $5^{\circ}C$, stopped date and period of rootstock growth, and sudden changed period of ABA contents, chicory has internal dormancy for two weeks from December 3 and low temperature requirement hours for the dormancy breaking is about 240.

• Korean journal of applied entomology
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• v.43 no.4 s.137
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• pp.329-332
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• 2004

This experiment was conducted to investigate pathogenicity of Spodoptera exigua nucleopolyhedrovirus (SeNPV) with different temperatures for mass production. In laboratory condition, $LC_{50}$ values of SeNPV were $9.797{\times}10^{3}PIBs/mL$ at $20^{\circ}C$ and $3.351{\times}10^{2}PIBs/mL$ at $32^{\circ}C$ in 2nd instar larvae. $LC_{50}$ of the other larval stage were similar to that of 2nd instar. $LT_{50}$ values of SeNPV was 9.0 days in $1.0{\times}10^{3}PIBs/mL$ but 6.9 to 3.5 days in $1.0{\times}10^{4-6}PIBs/mL$ against 3rd instar of Spodoptera exigua. $LT_{50}$ Values of $1.0{\times}10^{4}PIBs/mL$ were 5.7, 5.5 and 4.9 days in 24, 28 and $32^{\circ}C$, respectively. As a results, $LT_{50}$ was shortened with increase of temperatures up to $32^{\circ}C$ and also dependent on viral concentration and larval instars.

• Korean journal of applied entomology
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• v.60 no.3
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• pp.315-322
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• 2021

This study investigated the acaricidal and repellent activities of various plant extracts and Cnidium officinale-derived materials against Haemaphysalis longicornis. Among the 24 methanolic plant extracts, C. officinale showed the highest acaricidal activity (93.3%) against H. longicornis. Platycodon grandiflorus, Phytolacca americana, Magnolia denudata, Houttuynia cordata, C. officinale, and Pueraria montana showed significant differences in their repellent activity. Consequently, the activity of solvent-fractionated materials and the derived material of the C. officinale, was investigated and a 90% acaricidal effect was observed three days after hexane fraction treatment, indicating that the repellent response was statistically significant. Butylidenephthalide, which is a C. officinale-derived compound, showed 90% acaricidal activity seven days after treatment. Additionally, all H. longicornis moved to the untreated area in the t-tube olfactometer experiment, confirming the repellent activity of butylidenephthalide. Therefore, the results of this study suggest the use of C. officinale crude extract and butylidenephthalide as potent acaricidals and repellents against H. longicornis, respectively.

• Weed & Turfgrass Science
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• v.3 no.3
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• pp.225-231
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• 2014

Benzobicyclon induces phytotoxicity to Tongil type rice, although it is an efficient herbicide in paddy. This study was performed to figure out the benzobicyclon-induced phytotoxicity responses of whole crop forage rice genotypes that have the genetic background similar to Tongil type rice, under wet-seeded and transplanted conditions. Mogwoo demonstrated whitening symptom at all the temperatures in both wet-seeding and transplanting by the application of standard and double rates of benzobicyclon. Nokyang, Mogyang and Suweon560 exhibited no or negligible whitening and their plant heights were not reduced at standard rate of benzobicyclon. But in double rate application in wet-seeding, the three genotypes showed 0-8% of white plants at all temperature treatments and reduction in plant height was comparatively larger at $27^{\circ}C$. In transplanting, the double rate application of benzobicyclon at 24 and $27^{\circ}C$ induced 0-32% of whitening plants depending on genotypes while no whitening plants were observed at 18 and $21^{\circ}C$ in all genotypes. Reduction in biomass by double rate of benzobicyclon at 24 and $27^{\circ}C$ was greater than at 18 and $21^{\circ}C$. It is concluded that Mogwoo is extremely sensitive to benzobicyclon and Nokyang, Mogyang and Suweon560 are tolerant to the standard rate of benzobicyclon.

• Korean Journal Plant Pathology
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• v.13 no.3
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• pp.172-178
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• 1997

Xanthmonas campestris pv. campestris, causal agent of Black rot of crucifers, were isolated and identified from crucifer host. In order to determine the characters of X. c. pv. campestris associated with pathogenicity, Tn5 mutagenesis was carried out by conjugating with E. coli pJB4J1. Transconjugants were plate- assayed for missing cellulase, protease and amylase activity. A cellulase negative mutant was selected and tested for pathogenicity. Light microscopy and Scanning electron microscopy revealed that substomatal tissues were colonized by mutant, but was far less extensive than those by wild type. Stomatal surface and substomatal tissue appeared to have degraded by only wild type in 24 hrs and progression of pathogenesis was distinct in 48 hrs. In 6 days, wild type proliferated well in the tissue facilitated by cellulase activity. As a result, cellulase was determined as the important factor in pathogenesis.

• Research in Plant Disease
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• v.7 no.1
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• pp.8-10
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• 2001

A stem and root rot disease of kalanchoe (Kalanchoe sp.) which is a succulent plant that provides consumers with a durable flowering pot was found in Koyang, Kyounggi province, Korea in May 1998. We found that stems and roots of potted kalanchoe had dark brown spots at the soil level. The causal organism was identified as Pjytophtora nicotianae on the basis of mycological characteristics. The fungus produced markedly papillate, ovoid to spherical sporangia, and abundant chlamydospores. Sporangia were 20∼48$\times$24∼64㎛(avg. 35.0$\times$47.3㎛) in size, and optimum temperature for the mycelial growth of the isolate was 30$\^{C}$. The fungus showed relatively different pathogenicity to 14 kalanchoe cultivars including K. blossfelana cv. Florus. cultivars florsu, calypso, Maya, and Redsing were susceptible to thedisease in root dip inoculation. This is the first report demonstrating the stem rot on kalanchoe caused by P. nicotianae in Korea.

• 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).