• Korean journal of applied entomology
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• v.22 no.1 s.54
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• pp.7-14
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• 1983

Septoria brown spot closed by Septoria glycines is one of the most serious fungal diseases in soybean. Average yield reduction of 3 varieties for two years was $16.1\%$ by the septoria brown spot inoculation and $9.0\%$ by the natural infection as compared to fungicide-sprayed plots. Number of pods per plant and seed weight were significantly reduced while plant height, number of branches and number of nodes per plant were not affected. Yield reduction was positively correlated to the septoria brown spot severity in all varieties examined. Correlation coefficient $(r=0.38^*)$ between yield reduction and area under the disease progress curve was higher than that (r=0.156) between yield reduction and Van der Plank's apparent infection rate. Potential effect of the septoria brown spot on the soybean yield reduction estimated with the area under the disease progress curve was expressed by the equation of Y=4.38+0.05X $(r=0.0696^*,\;df=25)$.

• Mycobiology
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• v.46 no.3
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• pp.242-253
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• 2018

Onion (Allium cepa L.) is one of the major vegetable crops in Korea that are damaged and lost by pathogenic fungal infection during storage due to a lack of proper storage conditions. The aim of this study was to determine an appropriate control measure using thymol to increase the shelf life of onions. To control fungal infections that occur during low-temperature storage, it is necessary to identify the predominant fungal pathogens that appear in low-temperature storage houses. Botrytis aclada was found to be the most predominant fungal pathogen during low-temperature storage. The antifungal activity of the plant essential oil thymol was tested and compared to that of the existing sulfur treatments. B. aclada growth was significantly inhibited up to 16 weeks with spray treatments using a thymol solution. To identify an appropriate method for treating onions in a low-temperature storage house, thymol was delivered by two fumigation treatment methods, either by heating it in the granule form or as a solution at low-temperature storage conditions (in vivo). We confirmed that the disease severity was reduced up to 96% by fumigating thymol solution compared to the untreated control. The efficacy of the fumigation of thymol solution was validated by testing onions in a low-temperature storage house in Muan, Jeollanam-do. Based on these results, the present study suggests that fumigation of the thymol solution as a natural preservative and fungicide can be used as an eco-friendly substitute for existing methods to control postharvest disease in long-term storage crops on a commercial scale.

• The Korean Journal of Pesticide Science
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• v.12 no.2
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• pp.177-183
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• 2008

For the development of integrated pest management system by harmonizing biological and chemical control, some experiments were carried out to select low toxic pesticides against natural enemies. Leaf dipping method, body dipping method, and diet treatment method were used for the toxicity evaluation against Microplites mediator adults. We tested 49 different pesticides (34 insecticides, 11 fungicides, 4 herbicides) at recommending concentration commonly used to control insect pests, disease and up-land weeds in chinese cabbage field. 16 insecticides, 11 fungicides, and 4 herbicides were shown to be low toxic to Microplites mediator adults in the treatment of body dipping.

• Journal of the Korean Wood Science and Technology
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• v.31 no.1
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• pp.1-9
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• 2003

Antimicrobial activities of plant extractives were investigated to develop a natural fungicide. Two stilbenoids and five flavonoids were isolated from wood extractives of Hovenia dulcis (Rhamnaceae) which had been selected due to its high antifungal activity among the tested species. The chemical structures of isolated compounds were determinded as : 5-hydroxy-7-methoxyflavone, 5,7-dihydroxyflavone (chrysin), 5,7-dihydroxyflavanone (pinocembrin), 3,5,7-trihydroxyflavanone (pinobanksin), 3,4',5,7-tetrahydroxyflavanone (aromadendrin), 3-hydroxy-5-methoxystilbene and 3,5-dihydroxystilbene (pinosylvin) on the basis of Mass and NMR spectroscopic data. According to the results of antifungal test, 3-hydroxy-5-methoxystilbene was evaluated as the strongest antifungal compound among the tested compounds and next were pinocembrin and pinosylvin, but those also had high hyphal growth inhibition activities against C. parasitica, T. versicolor, T. palustris and T. viride. However, pinobanksin, 5-hydroxy-7-methoxyflavone, chrysin and aromadendrin showed very low antifungal activity. In this regard, it could inferred that high antifungal activity of wood extractives of H. dulcis were derived from 3-hydroxy-5-methoxystilbene, pinocembrin and pinosylvin, respectively.

• Journal of the Korean Wood Science and Technology
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• v.32 no.4
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• pp.8-17
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• 2004

Antifungal, antibacterial, and antioxidative activities of ethanol extracts from 65 families 263 species were investigated to select tree species for the utilization of natural fungicide or preservative resources. The antifungal activities of extracts from wood, leaf and bark were measured as hyphal growth inhibition rate using four plant pathogenic and five wood rotting fungi. High inhibitory effect on the fungi growth was found in five species of Pinaceae (Pinus koraiensis, P. rigida, P. densiflora, P. banksiana. Cedrus deodara), three species of Cupressaceae (Juniperus rigida, J. chinensis, Chamaecyparis obtusa) and three species of Leguminosae (Albizzia julibrisssin, Sophora japonica, Maackia amurensis), respectively. Antibacterial activities of ethanol extracts were determined by means of disc-agar plate diffusion method using three gram-positive and five gram-negative bacteria. The ethanol extracts, which showed prominent effect on the suppression of bacteria growth, were six species of Betulaceae (Carpinus tschonoskii, C. coreana, C. laxiflora, Alnus hirsuta, A. firma, Betula schmidtii), five species of Fagaceae (Castanopsis cuspidata var. sieboldii, Quercus serrata, Q. mongolica, Q aliena, C crenata), four species of Euphorbiaceae (Aleurites fordii, Sapium sebiferum, S japonicum Mallotus japonicus) and three species of Elaeagnaceae (Elaeagnus umbellata, Elaeagnus glanbra, Elaeagnus macrophylla). According to these results, the extracts from Zelkova serrata, Pinus densiflora, Maackia amurensis, Chamaecyparis obtusa and Juniperus chinensis could be available for natural fungicide or food preservatives, because ethanol extracts from these species indicated excellent antifungal and antibacterial activities. In order to test antioxidative activities of ethanol extracts, free radical scavenging method was adopted with 1,1-diphenyl-2-picrylhydrohydrazyl (DPPH). Free radical scavenging activity was proved very high in the extracts of eight species of Rosaceae (Eriobotrya japonica, Prunus takesimensis, P yedoensis, P padus, P armeniaca var. ansu, Chaenomeles sinensis, Stephanandra incisa, Rosa multiflora) and five species of Ericaceae (Rhododenron mucronulatum, R. scblippenbacbii, R. yedoense var. poukhanense, Vaccinium bracteatum, V oldbami), resvectively. It turned out from this study that only six species among 48 species of Rosaceae showed less than 80% free radical scavenging activity. As a consequences, it could be deduced that the components effective on antioxidative activity commonly exist in Rosaceae plant family.

• Korean journal of applied entomology
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• v.46 no.2
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• pp.251-259
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• 2007

For the development of integrated pest management system by harmonizing biological and chemical control, some experiments wee carried out to select low toxic pesticides against natural enemies. and their residual toxicity were evaluated. Leaf dipping method, body dipping method, and diet treatment method were set up for the toxicity evaluation against Cotesia glomerata adults. We had tested 46 different pesticides (31 insecticides, 11 fungicides, 4 herbicides) at recommending concentration commonly used to control diamond back moth, disease and up-land weeds in chinese cabbage field. Twenty three insecticides, eleven fungicides, and four herbicides were shown to be low toxic to C. glomerata adults in the treatment of body dipping. After insecticide spraying at recommending dose on the chinese cabbage, we examined residual effect of insecticides by introducing natural enemies on different days. Safety interval for the introduction of C. glomerata adults was established according to the residual toxicity of pesticides. Safe insecticides for the introduction of C. glomerata adults at one day after treatment (DAT) were thiacloprid, acephate, chlorfenapyr, clothianidin and at 3 DAT were imidacloprid, deltamethrin, thiamethoxam, dimethylvinphos, emamectin benzoate.

• The Korean Journal of Pesticide Science
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• v.9 no.4
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• pp.391-400
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• 2005

This study was undertaken to survey the pesticides used under the greenhouse cultivation of 9 vegetable crops including cucumber, tomato, strawberry, eggplant, hot pepper, paprika, lettuce, perilla leaves and green onion in the Southern area during the period of 2003-2004. The total number of farmers investigated was 202 which consisted of 124 conventional growers and 78 environment-friendly growers. The farmers were requested to record with respect to the crop's name, cultivation acreage, growing practices (conventional/environment-friendly), use purpose, pesticide kinds, usage quantity and application time of pesticides. The average usage quantity of pesticides for the 9 crops was 3.30 kg ai/ha in conventional growing and 0.47 kg ai/ha in environment-friendly growing. The average application time of pesticides was 11 times in conventional and 2 times in environment-friendly growing, with more than 90% cases as a foliar application. The number of active ingredients of pesticides was 34 in conventional and 10 in environment-friendly growing on the average per crop. The purpose of pesticide application was as a fungicide in 56% cases and as an insecticide in 43% cases.

• Applied Biological Chemistry
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• v.48 no.1
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• pp.1-15
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• 2005

Pathogens, insects and weeds have significantly reduced agricultural productivity. Thus, to increase the productivity, synthetic agricultural chemicals have been overused. However, these synthetic compounds that are different from natural products cannot be broken down easily in natural systems, causing the destruction of soil quality and agricultural environments and the gradually difficulty in continuous agriculture. Now agriculture is faced with the various problems of minimizing the damage in agricultural environments, securing the safety of human health, while simultaneously increasing agricultural productivity. Meanwhile, plants produce secondary metabolites to protect themselves from external invaders and to secure their region for survival. Plants infected with pathogens produce antibiotics phytoalexin; monocotyledonous plants produce flavonoids and diterpenoids phytoalexins, and dicotylodoneous plant, despite of infected pathogens, produce family-specific phytoalexin such as flavonoids in Leguminosae, indole derivatives in Cruciferae, sesquitepenoids in Solanaceae, coumarins in Umbelliferae, making the plant resistant to specific pathogen. Growth inhibitor or antifeedant substances to insects are terpenoids pyrethrin, azadirachtin, limonin, cedrelanoid, toosendanin and fraxinellone/dictamnine, and terpenoid-alkaloid mixed compounds sesquiterpene pyridine and norditerpenoids, and azepine-, amide-, loline-, stemofoline-, pyrrolizidine-alkaloids and so on. Also plants produces the substances to inhibit other plant growths to secure the regions for plant itself, which is including terpenoids essential oil and sesquiterpene lactone, and additionally, benzoxazinoids, glucosinolate, quassinoid, cyanogenic glycoside, saponin, sorgolennone, juglone and lots of other different of secondary metabolites. Hence, phytoalexin, an antibiotic compound produced by plants infected with pathogens, can be employed for pathogen control. Terpenoids and alkaloids inhibiting insect growth can be utilized for insect control. Allelochemicals, a compound released from a certain plant to hinder the growth of other plants for their survival, can be also used directly as a herbicides for weed control as well. Therefore, the use of the natural secondary metabolites for pest control might be one of the alternatives for environmentally friendly agriculture. However, the natural substances are destroyed easily causing low the pest-control efficacy, and also there is the limitation to producing the substances using plant cell. In the future, effects should be made to try to find the secondary metabolites with good pest-control effect and no harmful to human health. Also the biosynthetic pathways of secondary metabolites have to be elucidated continuously, and the metabolic engineering should be applied to improve transgenics having the resistance to specific pest.

• Korean Journal of Environmental Agriculture
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• v.28 no.2
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• pp.194-201
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• 2009

To evaluate the exposure of non-point source pesticide pollution in agricultural watershed and to investigate pesticide distribution and runoff from agricultural land, paddy field, upland and orchard, this experiment was carry out during crop growing seasons. The pesticide were detected twenty pesticides fungicide 4, insecticide 10, herbicide 6) in water of Neungchon agricultural watershed and detection concentrations were range 0.008${\sim}$7.59 ppb. Most of the detection pesticides were using pesticides to rice paddy fields to control fungi, insects, weeds. During the crop cultivation, the pesticide were detected total thirty pesticides by pepper field soil 6, orchard soil 4, sesame field soil 3 and rice paddy field soil 5, and pesticide concentrations were range 0.001${\sim}$0.109 ppm. Especially the herbicides were detected mainly in May and June in the stream water. The pesticide were detected thirty pesticides by fungicide 2, insecticide 6, herbicide 5 in water of Jungam Koseong agricultural watershed and detection concentrations were range 0.01${\sim}$7.21 ppb. In regard to the detected pesticides, the concentration of individual pesticides measured in surface water of the study areas never exceeded guidelines for agriculture chemicals concerning water quality-effluent from paddy fields in Japan (Katayama, 2003). Runoff rate of pesticides was range 0.07${\sim}$3.06 % from Kongju agricultural land to watershed after applied pesticides.

• Journal of Bio-Environment Control
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• v.21 no.3
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• pp.294-298
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• 2012

In sweet cherry (Prunus avium L.) growing there are several severe problem which have to be overcome to produce highly graded fruits because of fruit rots and fruit crackings, if there is frequent precipitation during immature fruit step and picking season. In order to reduce fungicide sprayings and produce qualified fruits in areas with rainy season like as South Korea, rain-sheltered growing is necessary absolutely. Sweet cherry blooms early to medium April in southern area of South Korea. If we depend on honeybees (Apis mellifera) distributed in natural ecosystem, it is not easy to get normal fruit-set every season because of low temperature around blooming time. And also bee keepers seldom sell honeybee hives as a pollinator during spring, instead they keep honeybee hives to get honey. Recently use of B. terrestris as a pollinator of cherry tomato, oriental pumpkin etc. grown in protected cultivation system increase abundantly. Therefore, in this study we studied B. terrestris as an alternate of honeybee to pollinate sweet cherry grown in rain shelter. In part of foraging activity B. terrestris shows staying on a cherry flower for about six second and visiting frequency of 11 flowers per minute. However A. mellifera stayed about 15 second on a flower and visited 4~5 flowers per minute. There were no significant difference in fruit-setting rate and fruit characteristics after using B. terrestris and A. mellifera as pollinators of sweet cherry. Consequently there is no negative effect when we use B. terrestris as an alternate pollinator of A. mellifera in sweet cherry cultivation under rain shelter.