• Korean journal of applied entomology
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• v.44 no.1 s.138
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• pp.31-36
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• 2005

Adoxophyes spp. are the major rests of a pear. The larvae attack both leaves and fruits. (Z)-9-tetradecenyl acetate (Z9-14:Ac), (Z)-11-tetradecenyl acetate (Z11-14:Ac), (E)-11-tetradecenyl acetate (E11-14:Ac) and 10-methyldodecyl acetate (10me-12:Ac) have been reported as the sex pheromone components of the genus Adoxophyes. Our objective was to determine the difference in sex pheromone composition of three different A. spp. populations each from Cheonan, Sangju, and Naju area orchards in Korea. Gas chromatography (GC) analyses of pheromone gland extracts of virgin females confirmed the presence of two compounds (Z9-14:Ac and Z11-14:Ac) in Cheonan and Sangju populations, and four compounds (Z9-14:Ac, Z11-14:Ac, E11-14:Ac and tome-12:Ac) in Naju population. The Z9-14:Ac and Z11-14:Ac were detected in the ratio of 80:20 in the Cheonan population and 3:97 in the Sangju population. Females of Naju population produced sex pheromone blend consisting of Z9-14:Ac, Z11-14:Ac, E11-14:Ac and 10me-12:Ac at a ratio of 31:62:6:1. Field trapping tests in pear orchards with Z9-14:Ac and Z11-14:Ac indicated that maximum captures of the male were obtained with traps baited by 80:20 in Cheonan, 10:90 in Sangju, and 30:70 in Naju. These results suggest that there are remarkable geographical variations in the sex pheromone composition of A. spp. in pear orchards in Korea, and taxonomic classification of these species must be carefully assessed.

• Korean Journal of Environmental Agriculture
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• v.16 no.2
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• pp.181-186
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• 1997

Since volcanic ash soils in Cheju island have high capacities of adsorption and immobilization of phosphate, a relatively high rate of P application has been recommended in citrus orchards for many years and such a large amount of P application could be problematic both in agricultural and environmental point of view. The objective of this study was to test whether arbuscular-mycorrhizae can be used to improve P availability in Cheju citrus orchard soils. Soil, root and leaf samples were taken from 14 citrus orchards of different location and soil texture. Mycorrhizal spore distribution in the soils, mycorrhizal infection ratio on the citrus roots, and mineral nutrients in leaf samples were determined. Numbers of mycorrhizal spore were in the range of $9,000{\sim}40,000/100g$ soil. The population level was not correlated with any of the soil characteristics examined. Mycorrhizae were found in all of the examined orchards and root infection ratio varied between $14{\sim}60%$. The mycorrhizae infection ratio differed substantially in different soils. Although root infection was high at soils with low extractable P level, it was not significantly correlated with other soil factors measured. Since a positive correlation was observed between leaf P concentration and root infection, enhancement of P uptake seemed to be associated with mycorrhizal infection. These results indicate that mycorrhizae could be a useful method to reduce P applications in Cheju citrus orchards.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.3
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• pp.215-219
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• 1994

This experiment was tried for finding out some soil chemical problems when new apple trees were replanted in old orchards. Soil samples were collected from the soil horizons in the old apple orchards cultivated over 40 years and reference soils. The non-cultivated reference soils were located near the old apple orchards and each of the soils was showed as the same pedon with each of the cultivated soils. The results were as follows : Soil pH showed a tendency to decrease in low horizons of the cultivated soils whereas increase in those of the uncultivated soils. As a comparision with each chemical component, the content of exchangeable Ca or total Mn was likely to be deficient in the cultivated soils. But all components except those were not like that. Total exchangeable cations in the cultivated soils were lower than in uncultivated soils. The pH in the cultivated soils showed very high positive correlation with total exchangeable cations. From those result, it was assumed that lower pH in lower horizon which would be originated from low content of total exchangeable cations, reacts as a factor for the deterioration of old apple orchard soil.

• The Korean Journal of Pesticide Science
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• v.19 no.2
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• pp.93-100
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• 2015

This study surveyed the selling, buying, usage, selection and spraying frequency of pesticides on apple orchards in Geochang, Gyeongsangnam-do province from 2012 to 2013 and found that the fungicides, insecticides and acaricides were sprayed $13.9{\pm}3.5$, $12.6{\pm}3.2$, and $2.6{\pm}1.3$ times per year, respectively. Fungicides were applied mainly to control for Diplocarpon mali, Colletotrichum gloeosporoides and Alternaria mali, whereas insecticides were sprayed mostly to control Grapholita molesta, Carposina sasakii insects. Dealers sold pesticides without monitoring of the pests in the apple orchards, and also sometimes sold pesticides which are non-registered for apple. Most of the farmers were highly relied on dealers' recommendations to choosing the brand product. Relating on Integrated Pest Management (IPM) on apple orchards in Geochang, residual active ingredient of frequently sprayed fungicides, insecticides, and acaricides were analyzed. Most applications of the fungicides, insecticides and acaricides were well corresponded with FAO's recommendations. For production of safe food and use of pesticides, it is requested to develope control calender and consideration of training program for farmers. The regional characteristics and environmental situation of the farm also should be considered.

• Research in Plant Disease
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• v.22 no.4
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• pp.276-283
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• 2016

Bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) occurred at 202 kiwifruit orchards for the survey period of 2013-2016, of which Psa biovar 2 (Psa2) and Psa biovar 3 (Psa3) were detected at 73 and 129 kiwifruit orchards, respectively. The number of kiwifruit orchards infected by Psa3 in 2016 increased nearly two times compared to 2015. Psa3 was detected from all the kiwifruit cultivars except some kiwiberry cultivars growing in Korea. Yellow-fleshed cultivars Hort16A and Jecy-gold and red-fleshed cultivar Hongyang were highly susceptible to Psa3. Our epidemiological and random amplification of polymorphic DNA analyses indicated that the first Psa3 incidence on Hongyang orchard in Sacheon, Gyoungnam might result from an introduction of Psa3-contaminated pollens from China for artificial pollination in 2014 and recent outbreaks of Psa3 in Sacheon and Goseong, Gyoungnam in 2016 might be due to rapid spread of bacterial canker by secondary infection of Psa3 from Hongyang orchard to neighboring Jecy-gold and Hayward orchards.

• Korean journal of applied entomology
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• v.53 no.4
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• pp.415-425
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• 2014

This study investigated population fluctuations in two mite species in apple orchards over 20-year period. The occurrence of two major mite pests infesting apple trees, two-spotted spider mite Tetranychus urticae and European red mite Panonychus ulmi (Acari: Tetranychidae), was investigated from 1992 to 2011 in major apple-producing districts, including four to eight cities, in the southern part of the Republic of Korea. The 20-year trend revealed that more orchards were infested by T. urticae from 1992 to 1999, but thereafter P. ulmi became dominant. The observed mean density of P. ulmi was consistent, whereas that of T. urticae fluctuated during this period. The analysis of occurrence in four time periods reveals that the density of T. urticae decreased after 2002. The monthly sampling, revealed that the density of P. ulmi was higher in April, whereas the density of T. urticae was higher from May to August. This change may be due to a change in the frequency of pesticide spraying, ground vegetation management, a decrease in nitrogen fertilization, and the overall orchard management practices. However, this projection should be examined in more detail. On the basis of the findings of this study, it can be concluded that cultural practices, including fertilization, and environmental changes, such as pesticide spray frequency and integrated pest management practices, affect species dominance and population densities of the two mite species in apple orchards.

• Korean Journal of Organic Agriculture
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• v.19 no.1
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• pp.93-107
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• 2011

This research was carried out to investigate invertebrate fauna with organic and conventional pear orchards, which used four collected methods; soil sampling for soil microorganism, pitfall, malaise, and black light trap for over ground species. Collected species were 37 species, 1,184 individuals in organic and 28 species, 501 individuals by soil sampling in conventional pear fields. Those were 38 species, 646 individuals and 29 species, 440 individuals by pitfall trap, 55 species 650 individuals and 47 species, 508 individuals by malaise trap, and 23 species, 201 individuals and 9 species, 42 individuals by black light trap. Collembola was collected 389 individuals in organic which was 5 times than in conventional in soil sampling. In pitfall trap, that was 183 individuals which was 3 times. The diversity indices of organic pear orchards were 1.956 in May, 2.638 in August and those of conventional was 1.426 in May, 2.011 in August in soil sampling. In pitfall trap, the dominant species were spiders, collembollan, and coleopteran. Among Coleoptera, indicator insects for the evaluation of agricultural environment suggested were Eusilpha jakowelewi as organic pear orchard and Anisodactykus punctatipennis and Pheropsophus jessoensis as conventional. Malaise trap was collected dominant species as Diptera and Hymenoptera of Braconidae and Ichneumonidae. The diversity indices of organic pear orchards were 2.952, 3.120, and 2.010 in pitfall, malaise and black light trap in over ground invertebrate sampling. The highest diversity was in malaise trap. The higher diversity indices, the lower dominance indices.

• Korean journal of applied entomology
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• v.50 no.3
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• pp.203-208
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• 2011

This study was conducted to evaluate Geometridae (Lepidoptera) species as pests and the damage they cause in citrus orchards in Jeju, Korea. Seven geometridae species occurred in citrus orchards: Ascotis selenaria, Ectropis excellens, Menophra senilis, Biston panterinaria, Ourapteryx nivea, Odontopera arida and Hypomecis punctinalis. Among them, A. selenaria was most abundant, followed by E. excellens and M. senilis. Most Geometridae larvae fed on citrus leaves, but A. selenaria larvae ate fruits and leaves. Fruit damage of Citrus unshiu appeared as gnawed scars caused by young larvae feeding on fruit surface. Fruit damage on Shiranui fruits appeared as a wide hole or deep scars caused by feeding by mature larvae (6th instar). Citrus leaves damage due to Geometridae larvae was high during May to June. Fruit damage started in late June as the spring-shoots of citrus hardened and increased sharply in late July. In the field experiment, fruit damage in the late season reached 4.2% in both 2008 and 2009 and reached 5.2% in 2010. In citrus orchards, A. selenaria larvae started to appear in mid-May and their populations peaked in mid June, late July, and early to mid-September. Adult males of A. selenaria had a maximum peak in mid-May, and two other peaks in early to late July and late August to early September. A. selenaria male adults were collected in a pheromone traps constantly throughout Jeju Island.

• Korean journal of applied entomology
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• v.53 no.3
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• pp.209-215
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• 2014

This study was performed to monitor the seasonal occurrence of Pseudococcus comstocki (Kuwana) by using pheromone traps and to test a mating disruption technique to control this pest in pear orchards. We compared the attractiveness of rubber septa loaded with 1.5 and 3.0 mg of the pheromone, 2,6-dimethyl-1,5-heptadien-3-yl acetate. A total of 1,021 and 1,431 males were caught in traps baited with 1.5 mg and 3 mg of the pheromone, respectively. The numbers of males caught were not affected by trap color, although yellow traps were more attractive than white traps. In 2012, P. comstocki males were captured between June and October, with peaks in late June, early August, and late September. In 2013, the males were trapped between June and October, with peaks in middle June, late July, and late September. In pheromone mating disruption tests, catches were reduced by 17.7, 65.3, and 62.9% in orchards treated with 450, 900, and 1,350 mg per 10 a of the pheromone, respectively. At harvest, 3.4, 2.9, and 4.8% of fruits in orchards treated with 450, 900, and 1,350 mg per 10 a were damaged by P. comstocki, while 9.5% were damaged in the control orchard.

• Korean Journal of Organic Agriculture
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• v.18 no.2
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• pp.221-232
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• 2010

During 2005~2009, current status on the occurrence and the management of the major disease, insect and mite pests were investigated in the non-chemical or organic cultured apple orchards in Korea. Numbers of certified organic or non-chemical apple orchards increased from 14 in 2005 to 78 in 2008. Severe damages on leaves and fruits were caused by the several diseases such as marssonina blotch, bitter rot, white rot, sooty blotch and flyspeck, and the several insect pests such as apple leaf-curling aphid, woolly apple aphid, oriental fruit moth and peach fruit moth on the almost certified organic or non-chemical pest control orchards. About 10 and 18 environmental-friendly materials were used to control diseases and insect or mite pests, respectively. But, lime sulfur and bordeaux mixture to diseases and machine oil, plant oil mixed with egg yolk, and pheromone mating disruptions to insect pests were effective under the adequate conditions.