• Korean journal of applied entomology
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• v.34 no.4
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• pp.295-299
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• 1995

This study was conducted to find the control methods, status of overwintering and seasonal occurrence of Erioccoccus largerstroemiae on persimmon trees in Ch'ondo area, Kyongbuk province in Korea. Usually, overwintering eggs were sheltered in bark, among them the rate of alive eggs was 28.7%. The activiation of garpe-myrtle scale showed from late April, and they have three generations per year. The first occurrence of larval stage of Erioccoccus largerstroemiae starts from late June to early July, the second occurrence begins from middle August to late August, and from late June to early July, the second occurrence begins from middle August to late August, and from middle September to late September is the third, thus, three peaks of occurrence revealed in early July middle August, and late September respectively. Average number of eggs conceived in female adult was 229.3. Spray effect of chemical control showed as follows; lime sulfur with tow applications of pesticides (late June, late August) at 97.8%, machine oil with tow applications of pesticides (late June, late August) at 96.8%. And during the growing period, the spray results using three applications of pesticide only (late June, late August, amid September) showed 77.2% in field condition.

• Korean Journal Plant Pathology
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• v.11 no.3
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• pp.210-216
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• 1995

Alternaria spp.were predominantly isolated from the abnormal leaf spot lesions of pear cultivars Niitaka and Nijiiseiki. Alternaria isolates from the cultivar Niitaka were not pathogenic to both cultivars, but the isolates from the cultivar Nijiiseiki developed typical lesions of black leaf spots and were identified as A. kikuchiana. However, no typical abnormal leaf spot lesions were produced by the Alternaria isolates. Foliar spray of twelve different agrochemicals including lime sulfur, either alone or in combinations, with 7 times applications from April to July failed to reduced the disease development. Application of 17 different pesticides including fungicides, insecticides and herbicides currently used in pear orchards did not cause leaf injury similar to the abnormal leaf spot. Simulated acid rain of as low as pH 3.0 did not incite any leaf lesions alike the abnormal spot lesions. Mineral contents in the leaves of both cultivars did not differ significantly between the healthy leaves and those with abnormal leaf spots. When cuttings of pear tree were obtained in February from newly emerged twigs of the healthy or the diseased trees of Niitaka and planted in sand in the greenhouse, only those from the diseased trees developed typical leaf lesions of the abnormal spot. These results indicate that abnormal leaf spots are caused by unknown systemic agents in pear trees, rather than by Alternaria spp., chemical injury or acid rain.

• Korean Journal of Soil Science and Fertilizer
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• v.51 no.1
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• pp.28-34
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• 2018

Yuzu (Citrus junos) gummosis disease, caused by Phytophthora nicotianae, was first reported in 1997. As known in citrus, Phytophthora is the most fastidious soil-borne pathogen to control. In order to minimize its damage to Citrus spp., integrated pest management (IPM) approach, including fungicide chemicals and resistant cultivars, is necessary. Therefore, in this study we tried to evaluate tolerance of yuzu cultivars and its related species against yuzu Phytophthora. Trifoliate orange was evaluated as a susceptible host to yuzu Phytophthora by both mycelial growth onto extract media and immature fruit inoculation. However, in zoospores spray-inoculation on 2-year-old cuttings tree, trifoliate orange appeared to have a resistant property as showing less than 6% diseased leaf rate. Among yuzu cultivars only 'Namhae No. 1' appeared resistant property against both P. nicotianae and P. citrophthora. The 'Namhae No. 1' showed 5.7% and 10.6% diseased leaf ratio by P. nicotianae and P. citrophthora, respectively. Clearly, in order to reduce damages caused by two yuzu Phytophthora, we suggest that growers may utilize a trifoliate orange as a rootstock and 'Namhae No. 1' as a scion for fruit production.

• Korean Journal of Environment and Ecology
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• v.24 no.2
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• pp.209-221
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• 2010

This study was carried out to apply basic data of the native trees for planting in the salinity area by the vegetation ecological selection. Which focused on native woody species to the tolerances of saline soil and salt spray drift on the coastal forests in the West-Sea, Korea. The soil salinity($EC_{1:5}$) was 0.11dS$m^{-1}$, ranging of 0.00dS$m^{-1}$~0.68dS$m^{-1}$. The soil salinity was gradually decreasing from Belt I to Belt Ⅳ except the Belt I in some coastal windbreaks. The order of decreasing soil salinity was Belt I>Belt II>Belt III>Belt Ⅳ and the soil salinity was $EC_{1:5}$ 0.14dS$m^{-1}$, 0.11dS$m^{-1}$, 0.10dS$m^{-1}$, and 0.08dS$m^{-1}$, respectively. The total 181 taxa consisted of 52 families, 104 genus, 157 species, and 24 varieties were recorded as the trees tolerating to both soil salinity and salt spray drift. The trees emerged in the highest degree of salinity($EC_{1:5}$ 0.51dS$m^{-1}$) was nothing but appearanced Pinus thunbergii Parl., Smilax china L., Quercus dentata Thunb. ex Murray, Quercus serrata Thunb. ex Murray and so on at the level of singular and ideal value. The emerged trees in the high salinity of $EC_{1:5}$0.41dS$m^{-1}$~0.50dS$m^{-1}$ were Albizia kalkora Prain, Melia azedarach L., Paederia scandens (Lour.) Merr. var. scandens These species were trees of tolerance to saline soil. The emerged woody species in all belts were Pinus rigida Mill., Pinus densiflora Siebold & Zucc., Pinus thunbergii Parl., Juniperus rigida Siebold & Zucc. and so on. The woody species with high important value(I.V.) were Pinus densiflora Siebold & Zucc., Pinus thunbergii Parl., Pseudosasa japonica (Siebold & Zucc. ex Steud.) Makino, Smilax china L., Platycarya strobilacea Siebold & Zucc. var. strobilacea for. strobilacea and so on, which can be classified as highly tolerant native trees to salt spray drift.

• Weed & Turfgrass Science
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• v.4 no.2
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• pp.104-110
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• 2015

This study was conducted for 3 years in an apple orchard to investigate the efficacy of the glufosinate-ammonium (GFA) SL for weed control in comparison to non-woven fabric mulch, sod culture and machinery cutting treatments. Glufosinate-ammonium SL 18% was applied with 2 to 3 times, and the extents of injury caused by the different weed control methods were also investigated during the 3 years. The highest level of weed control was obtained by glufosinate-ammonium 3 times spray (98.7%), followed by machinery cutting (95.1%), glufosinate-ammonium 2 times spray (81.5%) and natural sod culture (5.8%). Amounts of fruit production in three times application of glufosinate-ammonium 540 g a.i. $ha^{-1}$, twice application of GFA, machinery cutting, non-woven fabric processing, sod culture and untreated control were 27.2, 26.2, 25.3, 24.1, 20.4 and 13.3 kg, respectively. There was no toxicity symptom of glufosinate-ammonium on the whole tree such as fruit, bud, trunk, branch and flower during the 3 years.

• Research in Plant Disease
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• v.22 no.2
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• pp.81-93
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• 2016

Out of plant-associated bacteria, certain plant growth-promoting bacteria (PGPB) have been reported to increase plant growth and productivity and to elicit induced resistance against plant pathogens. In this study, our objective was to broaden the range of applications of leaf-colonizing PGPB for foliar parts of road tress and pepper. Total 1,056 isolates of endospore-forming bacteria from tree phylloplanes were collected and evaluated for the enzymatic activities including protease, lipase, and chitinase and antifungal capacities against two fungal pathogens, Colletotrichum graminicola and Botrytis cinerea. Fourteen isolates classified as members of the bacilli group displayed the capacity to colonize pepper leaves after spraying inoculation. Three strains, 5B6, 8D4, and 8G12, and the mixtures were employed to evaluate growth promotion, yield increase and defence responses under field condition. Additionally, foliar application of bacterial preparation was applied to the road tress in Yuseong, Daejeon, South Korea, resulted in increase of chlorophyll contents and leaf thickness, compared with non-treated control. The foliar application of microbial preparation reduced brown shot-hole disease of Prunus serrulata L. and advanced leaf abscission in Ginkgo biloba L. Collectively, our results suggest that leaf-colonizing bacteria provide potential microbial agents to increase the performance of woody plants such as tree and pepper through spray application.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.4
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• pp.225-232
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• 2003

Nutrients and water absorption by Citrus unshiu Marc. cv. Miyagawa Wase were examined using spray type of out-door hydroponics system. Three different concentration levels of nutrient solution were treated to citrus trees to examine nutrient uptake. To do so, concentration and the volume change of nutrient solution was measured for each treatment. By weighing the volume of solution and citrus trees, amounts of water uptake and fresh weight increase were observed periodically. Water uptake by trees increased as tree grew and time elapsed, but was lower at high level of nutrient concentration than the rest, due partly to the reduction in hydraulic conductance and to the sustained high salt concentration. Rapid increase in fresh weight and nutrient uptake occurred from May to July and from August to September. The amounts of nutrient uptake were significantly different among nutrient levels: the higher concentration, the greater uptake by citrus tree. The absorbed amounts of $NO_3$, K and Ca were much higher than those of $NH_4$, S, P, Mg, and Fe. Most mineral contents in leaves were proportional to the concentration of supplied nutrient solutions. From the results of nutrient absorption and contents in leaves at different levels of nutrient solutions, the composition of major elements for citrus nutrient solution can be modified as follows: 27.1, 16.5, 66.0, 80.0, and $24.0mg\;L^{-1}$ for N, P, K, Ca, and Mg, respectively.

• The Korean Journal of Pesticide Science
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• v.20 no.1
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• pp.56-65
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• 2016

Pine wood nematode, Bursaphlenchus xylophilus is a fatal damaging pest, infecting pinewood trees and is one of the serious forest pest in Korea. Trunk injection is one of the most effective method to protect the live pine trees from nematode infection. The aim of this research was to reveal the efficacy of the nematicidal materials from 46 Kyrgyzstan, 88 Vietnam plant materials and 21 active materials (${\alpha}$-terpinene, ${\alpha}$-pinene, ${\beta}$-thujaplicin, cinnamaldehyde, eugenol, emodin, geraniol, limonone, methyl palmitate, matrine, myrcene, methyl gallate, nicotine, quassin, resveratrol, rotenone, thymol, thujaplicin, terthiophene, tuberstemonine, ${\gamma}$-terpinene) isolated from plants for using as trunk injection agents. Eclipta prostrata extract was highly effective against pine wood nematode in plant extracts and terthiophene has the best nematicidal activity from active materials isolated from plants. Foliar spray of terthiophene on Japanese black pine (Pinus thunbergii) tree reduced proliferation of inoculated pine wood nematode at 22 days after treatment, however no efficacy was found over 22 days. Eclipta prostrata extract and terthiophene can be used as nematicide for further nematicidal efficacy test against any other plant parasitic nematodes and trunk injection efficacy against pine wood nematode.

• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.36-36
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• 2014

Apple blotch, caused by Marssonina coronaria, induce early defoliation in apple and leading to critical economic losses in apple orchards in Korea. Since M. coronaria is difficult to culture, we developed isolation and cultural method. We collected M. coronaria isolates from Gyeongbuk Province and then constructed phylogentic tree based on ITS regions. As the results, phylogenetic relationship indicated that all Korean isolates formed a same cluster and closely related to Chinese isolates [1]. Ecological characteristic of M. coronaria have been observed in apple orchards which located in Gyeongbuk Province from 2011 to present. As the results, the typical apple blotch symptoms were observed from July, and then the infected leaves were discolored and formed acervuli on the leaves. After rainfall, severe infection of symptoms such as discoloration and early defoliation were continuously observed until October. Also overwintered conidia were observed in next March on the fallen diseased leaves [2]. In the last 5 years, ascopores of M. coronaria were not observed in apple orchards which were severely infected by M. coronaria in Korea. Thus, it is assumed that overwintered conidia could be a primary inoculum of M. coronaria. Meanwhile, apple blotch has long latent periods compare to other apple disease. During the latent period, early diagnosis of apple blotch is the most important to control the disease by spray fungicide. In this reason, we developed novel diagnostic method to detect M. coronaria during latent period using optical coherence tomography (OCT) and Loop-mediated isothermal amplification (LAMP) method [2, 3]. In this presentation, it will introduce ecological characterization of M. coronaria in Korea and unique detection technique of M. coronaria in apple. It will be helpful to develop new strategies to control apple blotch in Korea.

• Research in Plant Disease
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• v.24 no.4
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• pp.249-256
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• 2018

Disease occurrence in apple cultivars on 13-30 apple orchards from April to October 1992-2010 was investigated at 30 days intervals in Gyeongbuk, Gyeongnam and Jeonbuk provinces of Korea. Apple cultivar 'Fuji' was found most susceptible and is being damaged by cedar apple rust, scab, gray mold, Alternaria blotch and Marssonia blotch as major leaf diseases that were observed. The percentage of occurrence of these leaf diseases varies from every year. This variation is based on different rainfall and temperature conditions, cultivation, root stock and changed system of fungicide spray during the particular year and season.