• Korean journal of applied entomology
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• v.35 no.3
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• pp.232-237
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• 1996

Toxicity of 5 acaricides, 4 insecticides. and 6 fungicides to the twospotted spider mite, Tetranychus urticae Koch, and its predator Amblyseius womersleyi Schicha was assessed in a laboratory using a leaf disk bioassay. Dicofol was equally very toxic to aduly females of T. urticae and A. womersleyi, and caused 46% and 40% mortality of eggs of those two species, respectively. Adult females of A. womersleyi dipped in Abamectin solution showed low mortality(16.6%), while all T. urticae females died within 24 hours after dipping. Three ovicidal acaricides (Tetradifon, Clofentezine, and Hexythiazox) showed no mortality of predator eggs, but more than 90% mortality of T. urticae eggs. Four insecticides (Teflubenzuron, Triflumuron, Diflubenzuron, and Imidacloprid) and three fungicides (Propineb, Fenarimol, and Polyoxin-B captan) were non toxic to the A. womersleyi adult females. The other fungicides (Chlorothalonil, Nuarimol.Mancozeb, and Folpet) were a little toxic to adult females of the predator, showing$\leq$23.3% mortality, It may be suggested from these results that 4 insecticides, 4 acaricides, and 6 fungicides described could be incorporated into the integrated pest management system with A. womersleyi in apple orchard.

• Korean journal of applied entomology
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• v.54 no.4
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• pp.369-374
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• 2015

Grapholita molesta (GM) has been considered as a major problem to apple and peach orchards. Mating disrupters have been applied to control the pest over the world as an Integrated Pest Management [IPM] tool. Various types of dispensers releasing mating disrupters have been developed with different formulation of wax, polyethylene tube and aerosol. In this study, the dispensers that were composed of ester waxes and polypropylene (PP) film were used as dispenser materials to analyze release pattern of GM pheromone compared with paraffin wax and polyethylene (PE) film. The release pattern in PP film group was consistent with time while PE film group irregular. Based on these results, Japan wax_PP film dispenser (Japan_PP) was manufactured and showed the mating disruption effect of 98% during 5months in peach orchard.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.479-484
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• 2012

The occurrence of plum fruit moth, Grapholita dimorpha, has been recently reported in apple orchards in Korea. It has been suspected that G. dimorpha and its related species, G. molesta, may occur simultaneously in other host plants. This study reports the occurrence of G. dimorpha in pear orchards of different localities in Korea. The identification of G. dimorpha was determined by morphological characters and the DNA marker. The cross-trapping of both species may be possible because the major sex pheromone (SP) compositions for the two species are similar. From the monitoring data, G. dimorpha and G. molesta were caught in SP lure traps of G. dimorpha and both species were also caught in SP lure traps of G. molesta. This cross-trapping of G. molesta to a SP lure of G. dimorpha varied significantly among pear orchards in different geographical localities. Furthermore, the occurrence peaks of the two species were not coincidental in all monitored orchards. These suggest that monitoring data obtained from each SP trap of both species in pear orchards may be mixed with two species, which would result in the over-estimation of population density and peak frequency on both species in pear orchards.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.4
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• pp.169-178
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• 1980

Ammonium nitrate explosion technique was applied to seek a convenient method for the establishment of orchard on the undulating to rolling land or hill side of Pogog clay loam soil (Fine Aquic Fragiudalfs : Planosols) having high bulk density and low permeability. Explosions were made by three ammonium nitrate explosives placed in the bottom of 90cm deep auger hole with every 2m interval (Explosion I) and 4m interval (Explosion II) respectively. The effect of the explosion on physical properties of the soil was investigated and compared with the effect induced by manual digging, excavation of $1m{\times}1m$ in diameter and depth (Manual digging I) and trenching of $1m{\times}1m{\times}25m$ in width, depth, and length (Manual digging II) respectively. The results investigated after 7 months from the treatments are summarized as follows : 1. The explosion or manual digging reduced bulk density and hardness, whereas the treatments increased porosity, hydraulic conductivity, and available moisture-holding capacity of the soil. 2. The explosion of 4 m interval improved physical properties of the soil to optimum level up to 70cm of the distance from the explosion core in the range of depth 0-60cm, while in the case of depth from 60 to 100cm the optimum level was achieved only within 50cm radius. 3. When exploded in 2 m interval, the effect in the 0-60cm depth was overlapped between two explosion cores. The effect in the depth between 60 and 100cm, however, was found to be independent of the explosion intervals. 4. The manual digging was only costly and laborious but effective only within the work-up zone. 5. For the soils having bulk density higher than $1.4g/cm^3$ after the treatments, the field capacity determined 72 hours after a heavy rain was lower than the laboratory estimate at the suction of 1/3 atm. 6. The top growth of apple tree for the first year revealed that the explosion seemed better treatment than the manual digging, even though the difference was insignificant.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.2
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• pp.103-110
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• 1993

This study was made to evaluate the chemical properties of 481 farmers' orchard fields in An-Seong area. And the reasonable ferilizer rates were recommended utilizing the result of soil analysis. The results are summarized as follows : 1. As the soil fertility status of collected soil samples were evaluated on the basis of temporary optimal range for each soil chemical properties, 12.7 to 49.6% of the total 481 farmers' fields were range for soil improvement. 2. The contents of chemical component have a tendancy to decrease with depth gradually from surface to subsoil. 3. According to the relationship between the contents of soil component in subsoil and those in surface soil, the fertility condition of subsoil could be estimated on the basis of analysis data of surface soil. 4. The multiple regression equation for pear yield prediction to the organic matter and exchangable calcium contents in the soil were obtained. 5. Referring the average value, distribution ratio compared to the optimum level for each soil chemical properties and standard fertilizer rate, the soil fertility status could be categorized as "High" "Medium" and "Low". For each category, the recommended amounts for NPK and organic matter application were established. 6. The recommended rates through soul fertility diagnosis were less than farmer's dosage in the range 7.1~7.7 kg/10a for N, 0.8~11.5 kg/10a for $P_2O_5$, 7.1~19.9 kg/10a for $K_2O$ and 90~116 kg/10a for lime.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.3
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• pp.141-152
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• 1973

The mineralogical studies of the eleven sub-soil samples derived from granite, granodiorite, diorite and arkose sandstone, taken from apple orchards in the province of Kyungsangbukdo, Korea are made to investigate the relationships between the mineral weathering, soil forming processes and mineralogical composition. The fine sand fraction (less than 0.2mm) and the clay fraction (less than 2 micron) are dispersed with the shaker after hydrogen peroxide treatment for the removal of organic matter, and separated from each suspension by gravity sedimentation. The fine sand are observed by mineral microscope and the clay are observed by X-ray diffraction patterns, differential thermal analysis curves and infrared spectrum. The outline of the results are as follows. 1. The primary minerals ; Quartz, changed-feldspar, plagioclase, alkali-feldspar are dominant in almost all samples, and some samples contain an appreciable amount of hornblende, biotite, muscovite and plant opal. There are also those samples which contain very small quantity of pyroxene group, tourmaline, epidote, cyanite, magnetite, volcanic glass and zircon. They are mainly derived from weathering products of granite, granodiorite, diorite, arkose or its mixtures. 2. All samples contain expanding or nonexpanding $14{\AA}$ minerals, illite and kaolin minerals, and some samples contain chlorite, cristobalite, gibbsite, and those primary minerals as quartz and feldspar, but the quantities vary according to the parent matrials. 3. Non-expanding $14{\AA}$ minerals may be dioctahadral vermiculite which sandwiches gibbsite layer or chlorite in between layer lattices. 4. As for clay minerals, montmorillonite was principal component in the samples derived from weathering products of arkose sandstone and tertiary. Minerals which are derived from weathering products of arkose have kaolin minerals and vermiculite as their principal component, and minerals derived from weathering products of acidic rock group are generally classified into two groups, the kaolin mineral group, and the kaolin minerals and vermiculite group.

• Korean journal of applied entomology
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• v.10 no.2
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• pp.109-116
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• 1971

The study involved determination of resistance levels of spider mites to Metasystox, Folidol and C-8514 using slide dip technique: a feid trial of alternative acaricides using an O/P resistant strain. 1. Resistant strains of two-spotted spider mite( Tetranychus urticae Koch) were collected from Taegu, Kyungsan, Chunchun, Yesan, Suwon, Osan and Chungju, and kept in the glasshouse through the experiments. Resistant strains of European red mite (Panonychus ulmi Koch) were collected from Chungju, Taegu, Yesan, Chunchun, Suwon and Whasung, and Wonju susceptible was collected. Immediately after collection, tests were applied. All strains except susceptible populations had regularly been sprayed with Organo-phosphates including Parathion (or Folidol), Metasystox, Phenkapton and Trithion for more than the ten Bast years; and Organo-chlorines such as Kelthane and C-8514 more than five years. Comparisons of the resistant strains and susceptible strains at the $LC_50$ values are as follows: a. With Metasystox, resistance levels of the Chungju, Taegu, Yesan, Chunchun and Suwon resistant strains of P. ulmi were respectively, 96,52,4,3 and 2, times as resistant as the Wonju susceptible strain. b. With Folidol, resistance levels of the Chungju, Chunchun, Yesan, Whasung and Suwon strains of P. ulmi showed respectively, 126, 48, 33, 30 and 6-fold resistance levels over the susceptible strain. c. With C-8514, resistance levels of the Taegu, Suwon, Whasung and Chungju strains of P. ulmi were 42, 31, 30 and 20 times greater than the susceptible strain, respectively. d. With Metasystox, resistance levels of the Taegu, Chunchun, Yesan and Suwon, strains of T urticae were respectively, 32,29,25 and 17 times as resistant as the susceptible strain. e. With C-8514, resistance levels of the Taegu, Chungju and Kyungsan strains of T. urticae showed respectively, 59, 29 and 19-fold resistance levels over the Osan strain. 2. Field trials were carried out to assess the toxicities of eleven alternative materials which would be used for control of O/P resistant strain of Panonychus ulmi. The acaricide groups represented were 2 Organo-chlorines (Kelthane MF and Prethylen), 1 carbamate (Furadan), 1 nitrophenyl (Morocide), 1 carbonate (Morestan), 1 tin(Plictran), 1 fluorine (Nissol), 2 mixtures (Fundal and Banmite) and Organo-phosphate (Phenkapton). Of all acaricides tested Kelthane, Plictran, Fundal and Morestan were the most effective; fol]owed by Banmite, Furadan, Prethylen and Nissol. Sumite and Morocide were intermediate, but Phenkapton(Organo-phosphate) was very poor. In other words, a first application of the above outstanding materials gave very high degrees of control of O/P resistant population of European red mite for about 7 to 12 days. However, the results indicate that secondary application would sometimes be necessary. There was no foliage damage to apple trees by any of the acaricides tested of the concentrations used.

• Research in Plant Disease
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• v.23 no.2
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• pp.150-158
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• 2017

Pear scab caused by Venturia nashicola has been reported as an important disease of pear resulting in lowering the quality of pear fruits. In this study, it was conducted to investigate the relationship between resistance of V. nashicola and mutation of ${\beta}$-tubulin gene and the fungicide resistance in field isolate group in benzimidazole fungicides. Responce of V. nashicola to carbendazim could be classified into 3 groups as sensitive that does not grow at all on PDA amended with $0.16{\mu}g/ml$ of carbendazim, low resistance that could not grow in $4.0{\mu}g/ml$ medium, and high resistance that can grow even at $100{\mu}g/ml$. Thirty isolates of V. nashicola collected from 3 regions as Wonju, Naju, and Okcheon were highly resistant to carbendazim. Analysis of the nucleotide sequence of ${\beta}$-tubulin gene of V. nashicola showed that there was no difference in the nucleotide sequence between the sensitive and the low-resistant isolate, but GAG at codon 198 (glutamic acid) was replaced with GCG (alanine) in the high-resistant isolate. Among 10 isolates obtained from the Okcheon, 5 isolates showed the substitution of glycine for glutamic acid, which were resistant to carbendazim, but more sensitive to the mixture of carbendazim and diethofencarb than others. Through these results, all isolates of V. nashicola isolated in pear orchard were found to be resistant to benzimidazoles. Also, mutants E198A and E198G at ${\beta}$-tubulin were found to be important mechanisms of V. nashicola resistance against benzimidazole fungicides.

• Korean journal of applied entomology
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• v.24 no.4 s.65
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• pp.183-190
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• 1986

Identification of fruit sucking moths, their larval host plant, and degree of damages to fruits were investigated in $1982{\sim}'83$ at two orchards in Cheonnam province. In this study, 4 families 30 species were collected as fruit sucking moths and among them 10 species are newly recorded in Korea as fruit sucking moth: Catocala electa(B.), Spirama helicina(H.), Erebus ephesperis(H.), Parallelia stuposa(F.), Simplicia niphona(B.), Marumba gaschkewitschii(B. et G.), Agrius convolvuli(L.), Thyatira batis (L.), and Spilosoma niveum(M.). Larval host plants of fruit sucking moths in the vicinity of the fruit orchard include Cocculus trilobus D., Albizzia julibrissin D., Pterocarya rhoifolia S., Jaglans mandshurica M., Solanum melongena L., Brassia campestris S., Rubus idaeus C., Thalictrum aquilegifol L., and Rhus succedanea L. As the damage on different varieties of the main fruit trees, plum was orderly Santa Rosa>Beauty, Apple was Chook>Hong Og, Peach was Choseng Baeg Do>Hwang Do>Baeg Do, and Grape was Campbell Early>Neo Mascat>Golden Queen. Seasonal occurrence of main fruit sucking moth Spirama retorta(C.) showed peak 3 times in early-July, late-July, early-September. Oraesia emerginata(F.) showed peak 3 times in late-July, early-August, early- September and Lagoptera juno(D.) showed peak only in late-July and Adrias tyrannus amurensis(S.) showed peak only in mid-July. Fruit sucking moths were immigrated from p.m. 6 to a.m. 2, with peak in p.m. 10 to p.m. 12.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.1
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• pp.55-64
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• 2019

The flowering seasons can be advanced due to climate change that would cause an abnormally warm winter. Such warm winter would increase the frequency of crop damages resulted from sudden occurrences of low temperature before and after the vegetative growth stages, e.g., the period from germination to flowering. The degree and pattern of freezing damage would differ by the development stage of each individual fruit tree even in an orchard. A critical temperature, e.g., killing temperature, has been used to predict freeze damage by low-temperature conditions under the assumption that such damage would be associated with the development stage of a fruit flower bud. However, it would be challenging to apply the critical temperature to a region where spatial variation in temperature would be considerably high. In the present study, a phenological model was used to estimate major bud development stages, which would be useful for prediction of regional risks for the freeze damages. We also derived a linear function to calculate a probabilistic freeze risk in spring, which can quantitatively evaluate the risk level based solely on forecasted weather data. We calculated the dates of freeze damage occurrences and spatial risk distribution according to main production areas by applying the spring freeze risk function to apple, peach, and pear crops in 2018. It was predicted that the most extensive low-temperature associated freeze damage could have occurred on April 8. It was also found that the risk function was useful to identify the main production areas where the greatest damage to a given crop could occur. These results suggest that the freezing damage associated with the occurrence of low-temperature events could decrease providing early warning for growers to respond abnormal weather conditions for their farm.