• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.4
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• pp.422-427
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• 1989

Weeds may compete detrimentally with the ginseng for moisture and nutrients but hand weeding is the only practical means of eliminating weeds after crop establishment. To define the effects of 2, 4-D herbicide application on the plant growth and root yield of Korean ginseng (Panax ginseng C. A. Meyer). the herbicide 2, 4-D was applied as a foliar spray with the rates of 0.5. 1.0. 1.5 and 2.0 times of the recommended herbicide dosage 70ml/l0a. The Korean ginseng treated with 2, 4-D in the rate of two times concentration was indistinguishable from nontreated plants in visual rating for foliar symptoms. There were no significant differences of the leaf length and width as well as the stem length and diameter in check plants and those recieving 2, 4-D treatments. The. berry maturing in 3 and 4-years old ginseng was not inhibited with 2, 4-D treatment. The root weight of the 4-years old ginseng plant was not reduced by 2, 4-D application of 2 times dosage. However. when the ginseng seedling was treated with 2, 4-D. detrimental phenomena as stem bending and dicoloration of marginal part of seedling leaf were occured but stem bending was recovered in a few days.

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.37-43
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• 2000

Effects of silicon application on development of colonies of Sphaerotheca fuliginea were examined. Cucumber plants were applied with nutrient solutions amended with different concentrations of soluble silicon and selected leaves were inoculated with known concentrations of conidia of the pathogen. Colony number per leaf, colony area per leaf, and germination rate of conidia of S. fuliginea collected from the inoculated leaves were reduced as silicate concentrations in the nutrient solutions increased from 0.05 to 4.10 mM. The increase in resistance of plants to mildew infection was apparently due to silicate accumulation in leaves, and there was no correlation between cation or ionic strength effects and the silicate treatments. Silicate treatment in growth medium remarkably suppressed powdery mildew development on cucumber. Colonies of mildew fungus were visible with over approx. 38.3% of the mature leaf surface, while that of the leaves in high Si plants was 2.3% observed at 51 days after transplanting. No significant differences were observed between 1.7 mM and 3.4mM silicate treatments. Conidial germination rates were significantly reduced by increasing Si amendments. Conidial germination ranged from 14.7 to 20.3% for plants grown in low Si solution(<1.40 mM), and from 9.0 to 12.4% for plants grown in high Si solution(>1.8 mM). Foliar applications of Si with ${\geq}$ 17.0 mM decreased the number of powdery mildew colonies. Persistence of Si foliar sprays effects on cucumber demonstrated that the 17 mM Si spray applied 4 days before inoculation with S. fuliginea reduced mildew colony formation. The relationship was positive and linear.

• Korean journal of applied entomology
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• v.47 no.1
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• pp.101-105
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• 2008

Effects of different application of nematicides (fosthiazate 5% G, ethoprophos 5% G, and diazinon 34% EC) for the control of Aphelenchoides fragariae in strawberry were evaluated in a greenhouse experiments. Mother strawberry (Fragaria grandiflora) cv. Yeohong were dipped in solution of nematicides (fosthiazate or ethoprophos at 2.5 g a.i./liter in $20^{\circ}C\;or\;46^{\circ}C$) for 10 min. and planted in a greenhouse for dipping treatment. For the compare, mother strawberry were dipped in hot water for 10 min. without chemicals. For soil treatment, fosthiazate or ethoprophos at 3 kg a.i./ha were mixed into soil. For foliar spray, diazinon at 3.4 g a.i./liter was sprayed at foliage until runoff. At 40, 80, and 100 days after planting, runners were harvested from each treatment and the rate of nematode infestation and the number of nematodes per plant were examined. After 100 days of planting, mother strawberry plants dipped in fosthiazate solution (2.5 g a.i./liter, $20^{\circ}C$) for 10 min. produced more number of healthy runners and reduced % of infected runner as much as 90% and also had fewer nematodes per runner. Fosthiazate was more effective than ethoprophos. Foliar application of diazinon was reduced A. fragariae populations only in early season. Hot water treatment and nematicide soil treatment were less effective.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.26 no.6
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• pp.155-164
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• 2023

Sedirea japonica is one of the critically endangered species in South Korea mostly due to artificial harms such as illegal collection and habitat destruction. Therefore, artificial propagation through improving germination rate, increasing growth, and controlling flowering is meaningful for the conservation and reintroduction of S. japonica. It is suggested that cytokinins are one of the multi-factors that contribute to plant growth and floral responses. Especially, exogenous cytokinins have been known to induce or promote shoot growth or earlier flowering in orchids. Therefore, it was investigated how the application of 6-benzylaminopurine (BA) influenced the growth and inflorescence of S. japonica. A foliar spray containing BA at 100, 200, 300, and 400 ppm was applied from 1st July to 30th December 2021. Leaf length, leaf length growth rate, leaf width, and width and length ratio were measured as growth-related factors. Visible inflorescence rate, inflorescence length, the number of flowers per inflorescence, and the distance between the stalks were measured as flowering-related factors. Growth-related factors except for leaf growth rate were not affected by BA treatments, while leaf growth rate was significantly increased by 200 ppm of BA treatment. The visible inflorescence rate increased by 200 ppm of BA treatment, and there seems an optimal concentration and threshold of BA treatment. An iterative experiment with more seedlings and measurement factors would be helpful to figure out the effects of exogenous BA treatment on S. japonica, and it can be applied for mass propagation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.6
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• pp.353-355
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• 2000

The seasonal occurrence of aphids was investigated in the soybean Held to increase the control efficiency of aphid vectors of Soybean Mosaic Virus. The patterns of aphids occurrence were different according to planting time. There were two peaks in late June and mid-August in aphid population in optimum seeding (May 20), whereas the peak was around mid-June in early seeding(Apr, 20). Acyrthosiphon solani was dominant Species in early seeding, while Aphis glycines was dominant in optimum seeding. In early seeding, SMV incidence increased rapidly between 20 June and 30 June, suggesting that virus spread was strongly correlated with increased colonization of aphids. Imidacloprid WP, benfuracarb EC and acephate WP showed a good effect for the control of aphids without phytotoxicity. In the plot with infurrow treatment of imidachloprid G until 52 days after shooting, aphids were controled effectively. Acephate WP was applied as a foliar spray at V4, V6, or V4/V6 stage and all the treatments were effective on reducing: SMV incidence.

• Korean Journal of Soil Science and Fertilizer
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• v.13 no.1
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• pp.45-51
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• 1980

The effects of propanil, MCPA; 2, 4 5-T and silvex on the numder of new root and tiller on Taichung Native 1, Caloro, PI 245717 and Bluebonnet 50 by root administration and foliar spray at 10 levels of concentration were investigated. Phenoxy herbicides changed the growth pottern in the way of increased number of tillers and new roots rather than plant height or root length. It was suggested that MCPA is only possible to increase tillering around applicable range. Silvex stimulated tillering at higher level than that required to stimulate new root formation. Varietal response on herbicides were different along with herbicide feeding part. There was trends that the higher nitrogen response varieties also have a greater response to stimulating effect of herbicide. Propanil had no effect on growth and no injury even about 20 times of higher concentration of phenoxy herbicide.

• Journal of Ginseng Research
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• v.42 no.2
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• pp.175-182
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• 2018

Background: The impact of fungicide azoxystrobin, applied as foliar spray, on the physiological and biochemical indices and ginsenoside contents of ginseng was studied in ginseng (Panax ginseng Mey. cv. "Ermaya") under natural environmental conditions. Different concentrations of 25% azoxystrobin SC (150 g a.i./ha and 225 g a.i./ha) on ginseng plants were sprayed three times, and the changes in physiological and biochemical indices and ginsenoside contents of ginseng leaves were tested. Methods: Physiological and biochemical indices were measured using a spectrophotometer (Shimadzu UV-2450). Every index was determined three times per replication. Extracts of ginsenosides were analyzed by HPLC (Shimadzu LC20-AB) utilizing a GL-Wondasil $C_{18}$ column. Results: Chlorophyll and soluble protein contents were significantly (p = 0.05) increased compared with the control by the application of azoxystrobin. Additionally, activities of superoxide dismutase, catalase, ascorbate peroxidase, peroxidase, and ginsenoside contents in azoxystrobin-treated plants were improved, and malondialdehyde content and $O_2^-$ contents were reduced effectively. Azoxystrobin treatments to ginseng plants at all growth stages suggested that the azoxystrobin-induced delay of senescence was due to an enhanced antioxidant enzyme activity protecting the plants from harmful active oxygen species. When the dose of azoxystrobin was 225 g a.i./ha, the effect was more significant. Conclusion: This work suggested that azoxystrobin played a role in delaying senescence by changing physiological and biochemical indices and improving ginsenoside contents in ginseng leaves.

• Korean Journal of Organic Agriculture
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• v.21 no.2
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• pp.265-270
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• 2013

Cooking oil and yolk mixture (COY) was applied to control the powdery mildew of sweet persimmon at the research field of Gyeongsangnam-do Agricultural Research and Extension Services from 2010 to 2011. COY was sprayed three times with 10 days interval on foliar parts of sweet persimmon and the disease development was monitored after 5 days of final spray. Diseased leaf area rate was 13.4% and the control efficacy of COY against powdery mildew was 80.5%. Disease rate was 68.6% on negative control. Using scanning electron microscope (SEM), the morphological changes of the powdery mildew fungus on the leaf surface were observed. On COY-treated leaves, fungal mycellia were morphologically characterized by a loss in cell volume, shriveling, plasma membrane rupture, and subsequent loss of intracellular contents. It may due to the destruction of fungal cell wall or membrane structure.

• Research in Plant Disease
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• v.11 no.1
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• pp.39-42
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• 2005

Powdery mildew, caused by Sphaerotheca aphanis var. aphanis, is an economically significant disease of strawberry in Korea. When powdery mildew is not controlled adequately, it often spreads rapidly through strawberry plants and damage is associated with reduced yields. Proper timing of fungicide applications is, therefore, essential for effective disease control. This study evaluated the efficacy by application schedule of fungicides before harvest stage for preventing powdery mildew in 2001-2003. The systemic fungicides, azoxystrobin, kresoxim-methyl, and cupper fungicide DBEDC were applied preventively during the first part of the cultivating season. Preventative applications of DBEDC by dipping treatment before transplanting and kresoxim-methyl by foliar spray before blooming stage were one of the most effective control schedule tested to prevent and manage this disease. This research demonstrated the significance of application time to control of powdery mildew, particularly provided elimination unnecessary sprays of agrochemicals and reduction costs for strawberry growers.

• The Plant Pathology Journal
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• v.37 no.2
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• pp.137-151
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• 2021

The present study describes the bacterial blight of walnut, caused by Xanthomonas arboricola pv. juglandis (Xaj) in the northern Gyeongbuk province, Korea. Disease symptoms that appear very similar to anthracnose symptoms were observed in walnut trees in June 2016. Pathogens were isolated from disease infected leaves, fruits, shoots, bud, flower bud of walnut, and cultured onto yeast dextrose carbonate agar plates. Isolated bacteria with bacterial blight symptoms were characterized for their nutrient utilization profiles using Biolog GN2 and Vitek 2. In addition, isolates were subjected to physiological, biochemical, and morphological characterizations. Furthermore, isolates were identified using 16S rDNA sequence analysis, and multi-locus sequence analysis using atpD, dnaK, efp, and rpoD. To confirm pathogenicity, leaves, fruits, and stems of 3-year-old walnut plants were inoculated with bacterial pathogen suspensions as a foliar spray. One week after inoculation, the gray spots on leaves and yellow halos around the spots were developed. Fruits and stems showed browning symptoms. The pathogen Xaj was re-isolated from all symptomatic tissues to fulfill Koch's postulates, while symptoms were not appeared on control plants. On the other hand, the symptoms were very similar to the symptoms of anthracnose caused by Colletotrichum gloeosporioides. When walnut plants were inoculated with combined pathogens of Xaj and C. gloeosporioides, disease symptoms were greater in comparison with when inoculated alone. Xaj population size was more in the month of April than March due to their dormancy in March, and sensitive to antibiotics such as oxytetracycline and streptomycin, while resistant to copper sulfate.