• Korean Journal of Weed Science
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• v.1 no.1
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• pp.21-29
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• 1981

Nationwide survey of weed population in paddy rice field was conducted from 1760 fields all around Republic of Korea in 1981. The weed species observed include 2 species of grasses, 7 species of sedges, and 18 species of broadleaf weeds, and the dominant weed species were Monochoria vaginalis, Sagitraria trifolia, Potamogeton distinstus, Sagittaria pygmea and Cyperus serotinus. More and many weeds were growing in single cropped field than double cropped field. In single cropped fields, weed population was reduced when autumn plowing was conducted. In double cropped fields, more weeds were growing in barley or wheat grown fields than vegetable gown fields. Among the five paddy soil types, more weeds were growing in saline soils and poorly drained soils than others. The proportion of annual and perennial weeds in national average was 44% and 56%, and perennials became more dominant in central part of the peninsula. Autumn plowing and double cropping appeared to reduce the perennial weed population, however, the increased perennial weed population, presumably due to continuous use of herbicides which controls mostly annuals, seemed to an urgent problem to be solved.

• Journal of the Korean Society of Tobacco Science
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• v.11 no.1
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• pp.41-48
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• 1989

The significance of soil and/or rhisosphere populations of Erwinia carotovora sobsp. carotovora (Ecc) as a source of primary inoculum for tobacco hollow stalk disease has been demonstrated conclusively. The survival of Ecc in field soils fter overwintering was estimated by using the enrichment technique. The population number of pectolytic erwinia (PE) in field soils relatively decreased at the rate of 102-104 colony forming unit(CFU) per g of soil after overwintering. Higher level of PE population overwintered in the rhlzosphere foils of tobacco stubbles and detected more frequently in rhizosphere soils of weed plants than in those of bare fields. All of the tobacco stubbles collected from fields where tobacco had been grown the previous year contained Ecc. The more survived population number of PE at the 30cm depth of artifitiany infested soils than at the upper of those by introducing with diseased tobacco plant tissue after overwintering. Ecc overwintered effectively in rhizosphere soils of tobacco stubbles, overwintered weeds and tobacco debris in field soils.

• Weed & Turfgrass Science
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• v.3 no.2
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• pp.121-129
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• 2014

We investigated turfgrass diseases and inoculum density at nationwide turfgrass cultivation sites in year of 2013. Occurrences of large patch and rust disease appeared in September. Brown patch recorded in September to October at Namhea and Pythium blight disease occurred outbreaks in early July at Namhea site. Some sites in Namhea damaged 3% area of total cultivation field by Sclerotinia homoeocarp. In Daepyeong (Gyeongnam), Fairy ring and large patch were recorded. Severe takeall and fairy ring have been observed in Gochang-si. Multi-site in Cheongju-si, brown patch was observed in pandemic level. Interesting enough, a cool-season turfgrass cultivate sites in Pyeongtaek-si brown patch, leaf blast, summer patch, and Curvularia leaf spot were investigated during the surveys period. Inoculum densities (Rhizoctonia spp.) at turfgrass cultivations sites were increased as cumulatively in all survey sites. The investigation result indicated that the disease occurrence and pathogens are similar as diseases in golf courses.

• Korean journal of applied entomology
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• v.44 no.1 s.138
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• pp.73-90
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• 2005

Although the history of IPM can be traced back to the late 19th century, when ecology was identified as the foundation for scientific plant protection, it has been more than thirty years since first enunciation. Since than, the concept of IPM has evolved in multiple paths not only in entomology but in plant pathology and in weed science, and the philosophy has become a firm foundation to the science of plant protection. The IPM concept has gained wide general acceptance, however, because of the many-facet aspects, there has been some controversy and/or misunderstanding by the students and practitioners. In this paper, I was tried to review the concepts of IPM and to resolve the contradiction between the philosophy and practical techniques. On this line, the historical background and the concept of economic injury level, which is the foundation of the concepts, are reviewed and discussed the sampling techniques and the population dynamics of single pest, which were basic to the rational and effective application of the management techniques. IPM is not a science per se but it is a technique and it should be applicable to the real conditions. For this purpose, the information on the pests should be transferred to the producers as fast as possible. From such, some of my own opinion is presented in relation to current systems of the pest occurrence forecasting.

• Korean journal of applied entomology
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• v.44 no.2
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• pp.115-123
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• 2005

Historical changes of population abundances of European red mite (ERM), Panonychus ulmi (Koch), and two-spotted spider mite (TSSM), Tetranychus urticae (Koch) (Acari: Tetranychidae), were described in selected apple orchards in the National Horticultural Research Institute (NHRI, Suwon, Korea), based on research reports of the NHRI from 1958 to 1998. ERM was an abundant species up to 1970, and TSSM became a dominant species after 1980. The change occurred around mid 1970. Three hypotheses were made to explain the change: TSSM competitively replaces ERM, ground cover weeds are a major influencing factor on movement of TSSM (TSSM movement into trees is accelerated by destroying weeds), and ERM and TSSM populations are regulated by natural enemy complexes when the orchard system is not disrupted. And long-term results of the interaction between two species were projected according to the combination of different orchard management strategies: pesticide sprays (non-selective toxic pesticide spray : heavy pesticide pressure (HPP), and selective soft pesticide spray = low pesticide pressure (LPP)) and weed control methods (grass planting, and clean culture system with herbicides). In the HPP and grass planting system, ERMs are abundant because ERM can avoid competition with TSSM as movement of TSSM to trees are restricted, and natural enemy complexes are destroyed by toxic pesticides. In the HPP and clean culture system, TSSMs are abundant because TSSM moves to trees from early season and competitively replaces ERM. In the LPP and grass planting system, ERMs are abundant because movement of TSSM to trees is reduced, but they do not build up a high population density since their densities are regulated by natural enemy complexes. In the LPP and clean culture system, TSSM moves to trees and competes with ERM, but the competition pressure is reduced because population densities of mites are regulated in a lower level by natural enemy complexes. So, ERM can occurs in late season. Thus, two species can coexist temporarily with more ERM in early season and more TSSM in late season. TSSM abundant phenomenon presented in this study can be partially explained as a result of long-term interaction between ERM and TSSM under the HPP and clean culture system.