• Landscaping Tree
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• s.127
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• pp.32-36
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• 2012

수목에 있어서 해충방제란 인간에게 경제적 손실을 초래하고 해충의 활동을 억제하는 것으로서, 수목 해충의 밀도 개체수를 일정한 수준 이하로 조절하는 것을 의미한다. 즉 유해한 생물이 존재하더라도 그 밀도가 인간에게 심각한 피해를 줄 정도가 아니면 굳이 시간과 경비를 투자하여 방제 작업을 수행할 필요가 없다. 어떤 해충의 밀도가 점점 높아져서 이들에 의한 피해를 방치 하였을 때 예상되는 손실액이 방제에 소요될 제반 비용보다 높을 경우에는 방제 수단을 적용해야 할 것이며, 이러한 해충에 의한 손실액과 방제비용이 같을 때의 해충밀도를 경제적 피해수준이라고 한다. 따라서 경제적 피해수준을 경계로 하여 방제를 할 것인가 말 것인가를 결정하게 되며 조경수의 경우에는 경관미적 가치도 이러한 경제적 피해수준에 반영되어야 한다고 생각된다. 해충의 방제법을 대별하여 보면 기계적 방제법, 물리적 방제법, 화학적 방제법, 생물학적 방제법, 임업적 방제법, 페로몬과 기타 생리활성물질을 이용한 방제법, 법적 방제법으로 분류할 수 있다. 그러나 최근의 수목해충 방제는 화학적 방제 일변도의 방제가 이루어지고 있기 때문에 환경오염 등 생태환경에 영향을 주고 있는 상황에 있다. 이러한 관점에서 본다면 수목해충 방제는 여러 가지의 방제법을 적지 적소에 활용할 수 있는 종합적인 방제방법이 필요한 시점이라고 할 수 있다. 특히 화학적 방제를 할 시의 주의점 등 각각의 방제법에 대하여는 추후 살펴보도록 하겠으며, 본 지면에서는 직접적 방제법인 기계적 방제법과 물리적인 방제법에 대하여 소개하도록 하겠다.

• Research in Plant Disease
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• v.16 no.3
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• pp.285-289
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• 2010

The experiments were carried out in fields for two years from 2008 to assess yield losses of squash due to powdery mildew caused by Sphaerotheca fuliginea and to determine its economic thresholds. Powdery mildew disease was first observed in late June, about 50 days after field-transplanting, progressed rapidly during late July to early August, and began to reduce from late August. Powdery mildew severity was negatively correlated with squash yields. A positive correlation was observed between fruit weight and % marketable fruits. A simple linear regression model was obtained as Y=-10.399 X + 6607.5 with $R^2$ = 0.9700 when squash yields (Y) was predicted using powdery mildew severity as an independent variable(X). Spray threshold for maximizing squash yields without economic considerations was estimated as 6.5% in terms of leaf lesion area with powdery mildew. Economic threshold and economic spray threshold able to compensate the costs of fungicide sprays were determined as 21.6% and 17.3% in leaf lesion area, respectively.

• The Korean Journal of Pesticide Science
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• v.14 no.2
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• pp.133-137
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• 2010

A field investigation was carried out for two years to analyze yield loss due to soybean anthracnose caused by Colletotrichum truncatum and to determine its economic threshold limit. Anthracnose severity in terms of % diseased pods was negatively correlated with yield, number of normal seeds per plant and number of pods per plant, and positively correlated with % abnormal seeds with correlation coefficients of -0.85, -0.78, -0.64, and 0.80, respectively. A simple linear regression model was obtained as Y=-1.7781X+164.22 with $R^2$=0.8092, when the soybean yields (Y) were predicted using anthracnose severity (X) as an independent variable. The yield levels could be predicted as high as 80.92%. Based on this equation, spray threshold without economic considerations was estimated as 6.9 in % pods infected with anthracnose. Economic threshold limit and economic spray threshold able to compensate the costs of fungicide sprays were determined as 11.9% and 9.5%, respectively.

• The Korean Journal of Pesticide Science
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• v.19 no.2
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• pp.113-118
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• 2015

This study was carried out to develop the economic thresholds for powdery mildew on pepper. To investigate the relationship between powdery mildew incidence degree and yield, experimental plots with ten treatments as initial disease degree were established. Disease intensity exhibited negative and significant correlation with fruit characters like fruit length, fruit diameter, fruit weight. The adverse effect of the disease on these characteristics was low yield, exhibiting significant negative correlation with disease intensity. There existed close correlation between rate of infected leaf area and yields in the plastic house (Chonhatongil: Y = -3.44X+291.09 $R^2=0.73$, Buchon: Y = -2.14X+327.9 $R^2=0.78$). There existed close correlation between rate of infected leaf area and yield loss in the plastic house (Chonhatongil: Y = 2.14X+15.45 $R^2=0.76$ $r=0.87^{**}$, Buchon: Y = 3.44X+114.21 $R^2=0.73$ $r=0.85^{**}$). Control thresholds diseased rate on powdery mildew of pepper was below 3.2 to 7.3% rate of infected leaf area per plant in the plastic house. The economic thresholds for powdery mildew of pepper was below 3.8 to 6.2% rate of infected leaf area per plant in the plastic house.

• The Korean Journal of Pesticide Science
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• v.20 no.2
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• pp.145-151
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• 2016

This study was carried out to develop the economic thresholds for powdery mildew on eggplant. To investigate the relationship between powdery mildew incidence degree and yield, experimental plots with ten treatments as the initial disease degree were established. Disease severity exhibited negative and significant correlation with fruit weight and number of fruit. There existed close correlation between rate of diseased leaf area and yields in the greenhouse (control with fungicide Y = -36.5X+2938.5 $R^2=0.91$ $r=-0.913^*$, no fungicide: Y = -29.57X+2574.4 $R^2=0.73$ $r=-0.858^*$). There existed close correlation between rate of diseased leaf area and yield loss in the greenhouse (Y = 1.27X-2.4 $R^2=0.88$ $r=0.91^*$). The economic thresholds for powdery mildew on eggplant was below 14.7% rate of diseased leaf area per plant in the greenhouse.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2003.02a
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• pp.257-263
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• 2003

방제는 재배작물에 발생하는 병충해를 최소화하여 농산물의 품질을 향상시키고 생산성을 증대시키는 중요한 관리 작업이며, 작물을 재배하는 동안에 여러 번 작업해야하며 노동 강도가 크고 농약중독 위험 때문에 농민이 기피하는 작업이다. 방제 방법에는 화학적 방제와 생물학적 방제, 농업적 방제, 기계적 방제 등 여러 방법이 있다. 화학적 방제는 잡초나 해충, 균의 밀도가 경제적 피해 수준 이하에서 유지되면서 더욱 확산되지 않도록 천연 또는 인공 화학물질을 이용하여 병해충이나 잡초를 억제는 방제방법으로 현재는 물론 가까운 미래에도 주를 이룰 것으로 예상된다. (중략)

• Research in Plant Disease
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• v.19 no.3
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• pp.196-200
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• 2013

This study was carried out to investigate yield loss due to soybean leaf spot disease caused by Cercospora sojina Hara and to determine the economic threshold level. The investigations revealed highly significant correlations between disease severity (diseased leaf area) and yield components (pod number per plant, total grain number per plant, total grain weight per plant, percent of ripened grain, weight of hundred seed, and yield). The correlation coefficients between leaf spot severity and each component were -0.90, -0.90, -0.92, -0.99, -0.90 and -0.94, respectively. The yield was inversely proportional to the diseased leaf area increased. The regression equation, yield prediction model, between disease severity (x) and yield (y) was obtained as y = -3.7213x + 354.99 ($R^2$ = 0.9047). Based on the yield prediction model, economic injury level and economic threshold level could be set as 3.3% and 2.6% of diseased leaf area of soybean.

• The Korean Journal of Pesticide Science
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• v.19 no.4
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• pp.394-398
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• 2015

This research was performed to establish economic threshold (ET) for rice sheath blight disease with the cultivar Odeabyeo. Total yield and yield components, such as the panicle number per hill, the spikelet per panicle, the percent ripened grain and the thousand grain weight were evaluated depending on the disease severity of sheath blight on rice, respectively. Significant negative correlation between the percent of diseased hill (PDH) and total yield was observed (r = -0.93). Moreover, negative correlation coefficients were found between PDH and spikelet per panicle, and percent ripened grain (r = -0.66 and -0.77, respectively). There were no correlations between PDH and the panical number per hill, and a thousand grain weight, respectively. In this study, economic threshold level on sheath blight disease on rice was established on 7.8% of PDH.

• Research in Plant Disease
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• v.21 no.2
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• pp.89-93
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• 2015

This study was carried out to develop the economic thresholds for the control of bacterial spot of red pepper. The correlation between diseased leaf rate and yield in field was Y=-0.724X+281.58, $R^2=0.78$, $r=-0.88^{**}$. The correlation between diseased leaf rate and yield loss in field was Y=0.813X+15.95, $R^2=0.78$, $r=0.88^*$.We found that control thresholds was below 30.3% diseased leaves rate per plant in field. The economic control thresholds for bacterial spot of red pepper was below 16.3%.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.317-325
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• 2006

According to the preceding survey on insect pests of the green perilla, Perilla frutescens var. japonica HARA, The major pests were Aphis egomae Shinji, Pyrausta panopealis (Walker), Tetranychus urticae Koch, Polyphagotarsonemus lotus Banks, Tetranychus kanzawai Kishida at Guemsan, Chungnam, 2004. Aphis egomae causes nearly 100% injury of the green perilla in uncontrolled green houses. A field study was conducted to estimate economic injury levels (EILs) and control thresholds (CTs) for A. egomae injuring green perilla in green houses. Different densities of A. egomae ranged from 1 to 80 aphids per 100 plants in early inoculation. The mean injurying rate of plant was 2.4% to 40.5% at the end of June at differently inoculated levels. The economic loss time calculated by the ratio of cost managing aphid to market price (C/V) (C: cost managing aphid, V: Market price) in early season (from May to 13. June) was 5.8% and in peak season (from 13. June to 30. June) was 9.3%. Economic injury level in early and peak season was 5.3 aphids per plant and economic injury levels in peak season were 0.6 aphids per plant and 7.6% injured rate of plant. The control thresholds calculated by 80% level of economic injury level in peak season were 0.5aphids per plant and 6.1% injury rate of plant, respectively.