• The Korean Journal of Pesticide Science
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• v.13 no.2
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• pp.111-116
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• 2009

Juvenile hormone (JH) is an insect hormone mediating immature metamorphosis and adult reproduction. It also mediates immune responses to suppress hemocyte behavior, which is, however, activated by ecdysteroid. This study investigated an effect of a commercial pyriproxyfen (a JH agonist) formulation on a cellular immune response of the diamondback moth, Plutella xylostella, and analysed its mixture with Bacillus thuringiensis (Bt) in insecticidal potency. The commercial pyriproxyfen formulation significantly suppressed hemocyte-spreading behavior at low doses as did in pyriproxyfen technical grade. When the commercial pyriproxyfen formulation was mixed with Bt, Bt toxicity was significantly increased against P. xylostella larvae in laboratory. The mixture effect was then confirmed in field cultivating cabbage infested with P. xylostella larvae. The mixture showed a significantly enhanced mortality and reduced effective lethal time, compared to only Bt treatment.

• Journal of Environmental Science International
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• v.10 no.6
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• pp.451-459
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• 2001

Adsorption characteristics of triadimefon and diniconazole(pesticide) by natural zeolite($CLI_N$) and several synthetic zeolites were Investigated. The synthetic zeolites used En this study were as follows: Faujasite synthesized from coal fly ash($FAU_F$); Zeolite synthesized from the mixture of FAU and Na-Pl synthesized from the ratio of Cheju scoria 6 to coal fly ash 4 by weight($(FAU + Na-Pl)_{SF}$); waste fluid catalytic cracking catalyst($FCC_W$). The distribution coefficient, $K_D$ and Freundlich constant, $K_F$ decreased in the fellowing sequence : $FCC_W ＞ FAU_F ＞ (FAU + Na-Pl)_{SF} ＞CLI_N$ among the zeolites. The distribution coefficient and the adsorption capacity of $(FAU + Na-Pl)_{SF}$ for pesticides were 4.4 and 2.6 times higher for triamefon, and 2.0 and 2.4 times higher for diniconazole than those of $CLI_N$, respectively.

• The Korean Journal of Pesticide Science
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• v.19 no.2
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• pp.106-112
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• 2015

This experiment was carried out to investigate the best spray timing for the control of the bacterial shot hole with Bordeaux mixture (6-6) after wintering in the peach orchard. We sprayed Bordeaux mixture (6-6) on 'Mibaekdo', 'Yumyeong' and 'Cheonhong' of peach verities from late-March to mid-April in 2001, 2002 and 2014, and examined how much bacterial shot hole and chemical injure occurred. The infection rate of bacterial shot hole according to spray time was 10.2 to 11.7% at leaves, and 1.7 to 2.2% at fruits in 2002. And Efficacy of the Bordeaux mixture treatment for control of bacterial shot hole at full blooming time 21.2 to 30.4% at leaves, 1.7 to 4.4% at fruits in 2014. The chemical injure occurred slightly for one week hence. The fruit bearing rate was 20.7 to 29.8% at 'Mibaekdo', and 35.4 to 61.9% at 'Yumyeong' peach trees. When the spray at the time of blooming period by bordeaux mixture was investigated the control effect of bacterial shot hole disease. The infected leaves was better than 21 to 25% twice the quantity of finished products and bordeaux self-preparation about 28 to 30% base quantity of finished products, also the control efficacy was higher in infected fruits trends in bordeaux self-preparation method and twice the quantity of finished products.

• Journal of Microbiology and Biotechnology
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• v.22 no.1
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• pp.114-117
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• 2012

The biological control efficacy of a greenhouse soil bacterial mixture of Lactobacillus farraginis, Bacillus cereus, and Bacillus thuringiensis strains with antinematode activity was evaluated against the root-knot nematode Meloidogyne incognita. Two control groups planted in soil drenched with sterile distilled water or treated with the broad-spectrum carbamate pesticide carbofuran were used for comparison. The results suggest that the bacterial mixture is effective as a biocontrol agent against the root-knot nematode.

• The Korean Journal of Pesticide Science
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• v.19 no.4
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• pp.411-417
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• 2015

This study is conduced to investigate control efficacy of mixture of plant extracts which has been reported to control pest and Bacillus thuringiensis or alone. Control efficacy of 0.025% matrine or mixture of 0.016% matrine and BT ($5{\times}10^4cfu$) against $3^{rd}$ instar larvae of beet armyworm were best as 98.7% and 93.3%. Treatment of mixture of 0.01% matrine and BT ($5{\times}10^4cfu$) showed the mortality of 69.3%. In the case of neem, when the mixture of 0.1% neem and BT was applied to larvae of S. exigua, their mortality was 50.0% and weight of larvae were significantly different compare with control and only neem treatment. Therefore For effective control reducing population of beet armyworm and possibility to develop resistance against BT and eco-friendly agents, mixture of 0.016% Matrine and BT ($5{\times}10^4cfu$) could be used.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.376-382
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• 2014

The soluble loess-sulfur mixture allowed standing to remove insoluble component materials for five weeks after manufacturing. We decreased the pH level of soluble loess-sulfur mixture at pH 1.0 modified with decreasing 25% sodium hydroxide than original content. The pH ranges of soluble loess-sulfur mixture solutions were adjusted to pH 5.0-pH 11.0 (pH 1 unit) with brown rice vinegar (pH 2.8). The pH of original loess-sulfur mixture was about pH 13 and damaged the foliar parts and young leaves of tomato after twice application. These stock solutions can be diluted 500:1 with tap water to make a 0.05% working solution and were sprayed two times with 7 days interval to the leaf and stem of tomato, which were spontaneously infected with E. cichoracearum. Control efficacy of powdery mildew ranged from 85% to 90% at 7 days after first application. After second application, each loess-sulfur mixture solutions adjusted pH level significantly suppressed the powdery mildew disease in tomato. Consequently, loess-sulfur complex adjusted pH level with brown rice vinegar was suggested to be low in acute toxicity at all different pH values and suggested to use an agent for control of tomato powdery mildew in organic farming.

• The Korean Journal of Pesticide Science
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• v.13 no.4
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• pp.315-324
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• 2009

For the environmental friendly management of diamondback moth, Plutella xylostella (L.), Bacillus thuringiensis subsp. kurstaki ($30{\times}10^8\;cfu/mg$) and neem oil (0.5% azadirachtin) were used as green control agencies with mixed and alternative treatments on the chinese cabbage. When Bacillus thuringiensis subsp. kurstaki was applied to 1st and 2nd larva of P. xylostella with recommended concentration, their mortalities were reached to 100% by 2 days after treatment. In case of azadirachtin, its effect of mortality was continued for 7 days, and reached to 100% mortality. $LC_{50}$ values of Bacillus thuringiensis subsp. kurstaki and azadirachtin against 1st, 2nd, 3rd and 4th larva of P. xylostella were $2.8{\times}10^4$, $3.1{\times}10^4$, $3.4{\times}10^4$ and $1.5{\times}10^5\;cfu/ml$, and 2.7, 3.9, 4.7 and 7.1 ppm, respectively. The number of laid eggs of P. xylostella was reduced to 57.5 at 25 ppm of azadirachtin compared with control treatment. The hatch ratio was not significantly different with Bacillus thuringiensis subsp. kurstaki treatment in comparison with control treatment. However, when azadirachtin was applied, their hatch ratio were reduced to 25.8 and 45.4% at 25 and 50 ppm, respectively. On the other hand, emergence rate of eggs was not different with Bacillus thuringiensis subsp. kurstaki treatment, but 45.4% was shown in azadirachtin treatment with 50 ppm in comparison with control. When the mixture with Bacillus thuringiensis subsp. kurstaki and azadirachtin was applied to adults of P. xylostella, their mortality was higher than Bacillus thuringiensis subsp. kurstaki treatment only. These results are supposed that the mixture of Bacillus thuringiensis subsp. kurstaki and azadirachtin might be used as green control agents for reducing the demage of diamondback moth in the Chinse cabbage.

• The Korean Journal of Pesticide Science
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• v.18 no.3
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• pp.181-190
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• 2014

An entomopathogenic bacterium, Bacillus thuringiensis (Bt), can sporulate along with production of insecticidal Cry toxins. Bt Cry toxins exhibit relatively narrow spectrum to target insects due to their specific interactions with midgut receptors. This study designed several strategies to enhance Bt efficacy in target insect spectrum and insecticidal activity. Four Cry toxins were purified from four different Bt strains and showed relatively narrow target insect spectrum. However, the Cry mixtures significantly expanded their target insect spectra. The additional effect of baculovirus to Cry toxin was tested with recombinant baculoviruses expressing Cry1Ac or Cry1Ca. However, the baculovirus was little effective to expand target insect spectrum. Bacterial culture broth of Xenorhabdus nematophila (Xn) significantly suppressed insect cellular immune response and increased Cry toxicity. The addition of Xn culture broth to Cry mixture significantly enhanced Bt efficacy in target insect spectrum and insecticidal activity.

• The Korean Journal of Pesticide Science
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• v.11 no.3
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• pp.194-200
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• 2007

Insecticidal activity of 33 registered insecticides was tested against last nymphal instars and adults of ussur brown katydid (Paratlanticus ussuriensis). All experiments were tested at the recommended concentration of each insecticides by producer. Acephate, chlorpyrifos, diazinon, EPN and fenitrothion which were organophates, and a mixture combined with chlorpyrifos+${\alpha}$-cypemethrin showed 100% mortality of P. ussuriensis. But fipronil showed only 100% mortality in leaf-dipping method. Carbamates insecticidal groups, benfuracarb and furathiocarb were showed over 80% and phenthoate was $60{\sim}80%$ in mortality of P. ussuriensis. Among the mixture, etofenprox+diazinon and esfenvalerate+fenitrothion were showed 60-80% against last nymphal instars of P. ussuriensis. Otherwise, acephate, chlorpyrifos, diazinon, EPN and fenitrothion were showed 100% mortality of P. ussuriensis within only 24 hours after treatment, but there was no effective after then in residual tests with leaves.

• Korean Journal Plant Pathology
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• v.11 no.1
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• pp.17-29
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• 1995

This study was conducted from 1991 to 1993 to develop a fungicidal spray program for the apples exportable to the United States of America, in which quarantine and pesticide residue in agricultural products are strictly regulated. In 1991, 2 spray schedules were applied to an orchard, in one of which the 7 fungicides registered for apple both in Korea and U.S. were used, and in the other of which the Bordeaux mixture for which the tolerance was exempted in U.S. was used 2 times along with those 7 fungicides. The apple white rot and fruit infection by Alternaria mali were not effectively controlled by the 7 fungicides alone; however, the control efficacy was raised by adding the Bordeaux mixture to the spray schedule. In 1992, 4 spray schedules were applied in which the kinds of fungicides and spray intervals were different one another. The results suggested that an effective spray program can be developed by adopting the Bordeaux mixture for 3 times or adopting the imminoctadine-triacetate which has not tolerance level in U.S. for same times in the vulnerable stage of apple white rot and alternaria blotch. In spite of the high efficacies against major apple diseases, the Bordeaux mixture could not be recommended to the apple growers due to the various defects such as restrictions in compatibility with insecticides and acaricides, troublesomeness in preparation and spray, especially the harmful effect on the finish of Fuji apples. In 1993, a spray program adopting 3 times of imminoctadine-triacetate during the growing season of apple was developed, which not only can effectively control the major apple diseases but also avoid the pesticide residue problems if it was sprayed 2 or 3 times after bagging. On the basis of the 3 years results, a basic fungicide spray program was formulated in which 1~3 times of imminoctadine-triacetate and 1~2 times of bitertanol were adopted in addition of the 7 common fungicides registered in both countries. In the results of application of the spray schedule to the actual farming in the 4 areas of Kyungpook Province in 1994, no noticeable defects were detected at the first year trial. However, this spray program will be continuously evaluated and modified to obtain better control efficacies against major apple diseases.