• Korean journal of applied entomology
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• v.57 no.3
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• pp.209-220
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• 2018

Mating disruption (MD) has been widely used to effectively control Grapholita molesta in apple orchards. A simultaneous mating disruption (SMD) techniques have been developed to control both G. molesta and G. dimorpha. This study was performed to determine the practical parameters to apply the SMD technique to field conditions. To determine the application amount of SMD lures, a dispenser containing 10 mg pheromone was placed at different numbers of trees in an orchard. Application at every other tree (= one dispenser per two trees) was relatively safe to expect effective MD efficiency in both wax and polyethylene (PE) formulations. One time application at the end of March was enough to maintain a year round MD efficacy against both species. A fence treatment using food trap was applied to prevent any immigratory mated females from nearby untreated regions. To enhance the food trap by adding host-derived secondary compounds, terpinyl acetate (TA) was screened to be effective to attract females of Grapholita molesta among six compounds contained in apple fruit extracts. Among different TA concentrations, 0.05% TA treatment was the most effective to attract the adults. A mixture of TA and sugar was effective to attract and kill females and called FAKT (female attract-to-kill techniques). FAKT was treated at approximately 6 m interval at the edge of the apple orchards. The females trapped by the FAKT included mated females possessing vitellogenic oocytes. SMD supplemented with FAKT maintained the high MD efficacy and significantly suppressed leaf damage induced by the two insect pests compared to control or single SMD treatment.

• Journal of Bio-Environment Control
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• v.28 no.2
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• pp.126-133
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• 2019

In recent years, the deterioration of fruit quality caused by poor coloration and sunburn disorder has become serious problems in apple market, which is a result of the increase of surface temperature due to the abnormal temperature increase during summer season. This study was conducted to investigate the effect of wind net shading and fine water spray using sprinkler on fruit coloration, sunburn damage and overall fruit quality of 'Fuji' and 'Hongro' apples. Fifteen sprinklers (7L/hr) were installed at the orchard of the Chungcheongnam-do Agricultural Research and Extension Services, located in Sinam-myeon Chungcheongnam-do Korea, at a height of 3m above the apple tree of $1.5m{\times}3.5m$ north-south direction. Fine water spraying treatment was divided into day time spray (10:00 am to 6:00 pm) and all day spray (10:00 am to 10:00 pm) from early July to 10 days before harvest in 2017 and 2018 season, respectively. Temperature of the surface of apple fruit, characteristic of fruit, and degree of sunburn damage were investigated. In 'Fuji', the fruit surface temperature checked at 2 pm on August 10 was decreased considerably in the day time spray ($35.6^{\circ}C$) and wind net ($39.0^{\circ}C$) when compared with the untreated control ($44.4^{\circ}C$). Similarly, the fruit surface temperature also decreased considerably in the all day spray ($35.1^{\circ}C$) and wind net ($36.9^{\circ}C$) treatments when compared with the untreated control ($46.5^{\circ}C$) in 'Hongro' apples. The incidence of sunburn disorder was significantly decreased with day time spray (5.0%), all day spray (5.8%) and wind net (7.0%) when compared with untreated control (23.4%) in 'Fuji' apples. As a results, the treatment of fine water spray and wind net consequently showed 26% and 34% increase of redness ($a^*$) value in the skin color difference, respectively, in 'Fuji' apples.

• 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.

• Current Research on Agriculture and Life Sciences
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• v.2
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• pp.34-41
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• 1984

This study was conducted to investigate yearly changes of weeds occurring in orchard and to evaluate an effect of continuous herbicide application on weed population in apple fields. Digitaria sanguinalis, Cephalonoplos segetum, Calystegia hederacea, Polygonum aviculare, Echinochloa crus-galli, and Portulaca oleracea were observed to be the problem weeds in orchard with yearly similar species for a three-year, showing D. sanguinalis was single dominant species for a three-year experimental period. An increase of Simpson's index from 0.22 in the first year to 0.33 in the 3 rd year was observed in the oxyfluorfen treated plot, indicating that most of the weed species were well controlled, while in the untreated plot, D. sanguinalis was relatively single dominant species showing Simpson's index, 0.56 in the 1st year and decreased to 0.32 in the 3 rd year meaning diversification of weed species, and the same trend was also observed in community dominance. Dissimilarity coefficient, 41.6, observed in the weed populations of 1st year and 2nd year, increased up to 58.8 between 1st year and 3 rd year's weed populations in the oxyfluorfen treated plot, indicating that weed community was greatly affected by oxyfluorfen treatment. Based on 3 year's dry weight oxyfluorfen treatment controlled 95 % of weeds such as $149.3g/m^2$ dry weight in the untreated control plot, with a little yearly changes of dry weight. Composition of perennial and biennial weeds was about 59% in the herbicide treated plots and 30% in the untreated control, showing a relative increase of these weeds in the treated plot. However, total dry weight of these weeds was markedly low, showing less than 5% of the untreated one. An annual, D. sanguinalis composed of 70% of total dry weight in the untreated control.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.320-327
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• 2021

Freezing damage to fruit trees is frequently occurring due to cold in winter and low temperature in spring to abnormal weather caused by global warming. In particular, the freezing injury of deciduous fruit trees is highly dependent on the developmental stages of the flower buds. And the cold resistance is weakened as the growth progresses, so it is most vulnerable period from flowering to petal fall(post-bloom). Therefore, this study was conducted to analyze the cause of the freezing injury caused by severe low temperature to 'Fuji', which has a late flowering period more than 'Hongro' in April 2020. We investigated freezing injury rate in 'Fuji' and 'Hongro' apple trees damaged by natural low temperature at Boeun-gun, Chungbuk province in Korea. In addition, flower buds in the same developmental stage (tight cluster) were treated artificially low temperature to investigate the injury rate for accurate comparative analysis between varieties, and to analyze the soluble sugar and hormone contents in the flower buds. As a result of survey in natural low temperature, 'Fuji' had a higher injury rate than 'Hongro' in both orchards, and in particular, B orchard 'Fuji' had the highest injury rate of 60.5%. Also there were significantly difference in the freezing injury rate between 'Fuji' and 'Hongro' in artificially low temperature treatments. As a result of analyzing the soluble sugar contents in 'Hongro' was higher than 'Fuji'. Also ABA, IAA and SA contents were more increased in the damaged tissue than in the normal flower buds by low temperature treatments. Consequently, it was assumed that the freezing injury was closely related to soluble sugar contents in the flower buds. In particular, the freezing injury rate was negatively correlated with the sorbitol contents.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.1
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• pp.16-23
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• 2003

Soil and water quality was monitored in the Nakdong River basin to assess the impact of different agricultural practices. From five catchments, soil samples were collected at three times during 1996 to 1998, and water samples were collected at twelve times on July during 1995 to 1999. The major agricultural practices were paddy and upland farming in three areas surveyed: Youngju, Goryung, and Milyang. Apple orchards were located along in the Imgo-Cheon catchment. Intensive vegetable farming in plastic fIlm house was practiced in the Habin-Cheon catchment. Total N contents, 0.04-0.32%, of paddy soils were low in comparison with those of upland, orchard, and plastic film house soils. Available phosphate($P_2O_5$) contents, $2-421mg\;kg^{-1}$, in plastic film house soils were higher than those in paddy soils. In plastic film house and upland soils, CEC of soils were high. The N concentrations in most of the streams were higher than $1.0mg^{-1}$, the standard of agricultural irrigation water. The P concentrations were above $1.0mg^{-1}$, the standard of agricultural irrigation water and were higher than the minimum level for eutrophication, $0.01-0.05mg\;L^{-1}$ in most of the streams. In conclusion, nutrients by agricultural activity could affect water quality of streams near the agricultural fields. Good water quality in streams can be maintained by proper management of agricultural fields and by decreasing application amount of fertilizers in agricultural fields.

• Journal of Korean Society of Forest Science
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• v.103 no.2
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• pp.307-312
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• 2014

Wild boar have increased in recent years in Korea where damage to agricultural crops is considered as a social issue. The ecological studies on wild boar are essential for the effective management in the future. During May and December 2012, We collected 79 wild boar stomach samples from culling program implementation to reduce agricultural damage in Geochang County and analyzed stomach contents to figure out wild boar diet habit and which crop was preferred. There was seasonal variation in the diet. Plant foods represented up to 93.5% of the diet and were consumed more frequently than animal foods. Invertebrates occurred with high frequency but were underestimated in dry weight because they are rapidly digested. Agricultural crops consumed comprised mainly chestnuts(33%), rice(33%), and apples(24%). Agricultural crops are also a potentially important food resources for wild boar. The frequency of occurrence of earthworms was 50% of diet. Earthworm consumption generally increased in summer, and then decreased in winter. Our results show that wild boar can be considered an omnivore whose diet consists of plant and animal foods. To reduce wild boar agricultural damages, We have to focus on the prevention effort to rice paddy adjacent to chestnut forest and to apple orchard.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.236-246
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• 2014

Pesticide is used to protect the crops, but also become a cause of polluting the environment. Perform a risk assessment using physical and chemical properties, environmental fate and toxicity data in order to determine the pesticide registration. The aquatic model estimates pesticide concentrations in water bodies that result from pesticide applications to rice paddies and apple orchard. The used models are the PRZM, EXAMS and AGRO shell (PA5), Rice Water Quality Model (RICEWQ) and Screening Concentration In GROund Water (SCI-GROW). The residual concentration of water body was estimated using meteorological data, crop calendar and soil series of Korea. The chosen pesticides were butachlor, carbofuran, iprobenfos and tebuconazole. It has shown the potential that the RICEWQ is possible to predict residue level in water of butachlor and iprobenfos, because the maximum value in water monitoring data is lower than the peak concentration of the model, and the minimum value is lower than the average annual concentration of the model. But RICEWQ was insufficient to predict exposure concentrations in ground water. The estimated exposure concentrations of carbofuran in ground water is very higher than in surface water because of its low soil adsorption coefficient. Although tebuconazole were not detected in the water monitoring that means very low concentration, it is possible that the PA5 can be used to predict residue level in water.

• Korean journal of applied entomology
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• v.24 no.1 s.62
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• pp.19-24
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• 1985

Alternaria mali isolated from infected apples in storages and orchards of the four main apple growing areas of Taegu, Yesan, Jungup and Chungju in Korea was tested with various fungicides added in PSA medium. The fungal tolerance varied with little difference by orchard area and with great difference by king and concentration of fungicide. Minimum inhibitory concentration (MIC) of chlorothalonil and captafol was $100,238{\mu}g\;and\;81,000{\mu}g/ml$, respectively, showing low effects with high fungal tolerance; of iprodione and folpet was $3,285{\mu}g\;and\;3,000{\mu}g/ml$, respectively, showing moderate effects with moderate fungal tolerance; and of oxidong, polyoxin and polydong was $1,000{\mu}g,\;900{\mu}g\;and\;500{\mu}g/ml$, respectively, showing high effects with low fungal tolerance. Mycelial growth, conidia formation and conidia germination of the fungus showed a similar trend of response to the seven fungicides.

• Korean journal of applied entomology
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• v.56 no.1
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• pp.61-67
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• 2017

Two major sex pheromone components (Z-8-dodecenyl acetate and E-8-dodecenyl acetate) are known in the peach fruit moth, Grapholita molesta. From a putative biosynthetic pathway of these sex pheromone components, delta 10 desaturase ($10{\Delta}$ DES) has been proposed to play a crucial role in synthesizing a species-specific stereoisomer of the double bond. However, its molecular identity was not known. This study determined a putative desaturase (Gm-comp1575) as a $10{\Delta}$ DES candidate from G. molesta transcriptome constructed from the sex pheromone gland. Its open reading frame encodes 370 amino acid sequence with a predicted molecular weight at 43.2 kDa and isoelectric point at 8.77. It was predicted to have four transmembrane domains and six glycosylation sites at N-terminal or cytosolic domains. A phylogenetic analysis with its predicted amino acid sequence indicated that Gm-comp1575 is closely related with known $10{\Delta}$ DES genes of other insects. Gm-comp1575 transcript was detected in female adults at sex pheromone gland and other abdominal tissues. RNA interference of Gm-comp1575 significantly reduced attractiveness of virgin females in apple orchard compared to control females. These results suggest that Gm-comp1575 is associated with sex pheromone biosynthesis of G. molesta.