• Applied Biological Chemistry
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• v.44 no.2
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• pp.109-115
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• 2001

The foliar uptake of dimethomoiph induced by several nonionic surfactants was measured in order to study the correlations between the uptake rate of dimethomorph and the fungicidal activity to cucumber downy mildew. Dimethomorph was not absorbed in cucumber leaf in the absence of activator surfactant. And the curative effect of dimethomoiph WP to cucumber downy mildew was very low under the concentration of 250 ${\mu}g/ml$. But dimethomorph uptake was remarkably enhanced by addition of nonionic surfactants, such as polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, and polyoxyethylene stearyl ether. And the curative effect to cucumber downy mildew was enhanced with proportion to uptake rate of dimethomorph. The protective effect to cucumber downy mildew, however, tends to decrease with the increase of foliar uptake of dimethomorph. The uptake rate of dimethomorph to cucumber leaf was proportional to the content of polyoxyethylene cetyl ether in formulation, but was decreased with dilution.

• The Korean Journal of Pesticide Science
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• v.12 no.2
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• pp.118-126
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• 2008

In order to find the best compositions of the dimethomorph formulation containing fatty alcohol ethoxylate surfactants as an activator adjuvant and recommend the good management way of the formulations to allow an intended uptake rate, factors affecting foliar uptake of active ingredients into cucumber were investigated and compared each other. Among tested, the most important factors were air temperature in which plants were located after spraying of aqueous formulations containing activator adjuvant, and deposit of wax on the leaf surface of cucumber. Dimethomorph uptake was found to be increased by sunlight. When aqueous formulations had long-polyethoxylated fatty alcohol surfactants, the relative humidity of the room in which the plants were located after spraying with the formulations did not severely influence the foliar uptake. Maintaining a mild temperature and avoiding too strong sunlight after spraying with dimethomorph formulations were found to be resonable management strategies.

• The Korean Journal of Pesticide Science
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• v.6 no.1
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• pp.16-24
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• 2002

Research trends in the measurement of foliar uptake of pesticides and the recently proposed action mechanism of the surfactant-induced uptake of pesticides were reviewed with the related reports and studies. Major techniques used in those fields are bioassay, radiotracer techniques with leaves or cuticular membrane. Recently, a new method using Congo Red as a tracer was proposed. The limiting factor in the pesticides uptake into leaves is the waxy layer which consists of the epicuticular and cuticular wax. Physico-chemical parameters such as molar volume, water solubility and partition coefficient of pesticides have limited influences on the pesticide uptake into leaves. Polydisperse ethoxylated fatty alcohol surfactants are well known as the good activator for many pesticides. It is now generally agreed that uptake activation is not related to the intrinsic surface active properties of surfactants such as surface activity, solvent property, humectancy and critical micelle concentration. Recent studies using ESR-spectroscopy revealed that the surfactants have an unspecific plasticising effect on the molecular structure of the wax and cuticular matrix, leading to increased mobilities of pesticides. Penetration of surfactants into waxy layer altered the pesticide mobility in wax and the partition coefficient of pesticide, and then the pesticides penetration into leaves was enhanced temporally. The enhancing effect of surfactant could be significantly different depending on the carbon number of aliphatic moiety and the number of ethoxy group in polyoxyethylene chain of surfactants. It is suggested that the rate of penetration of surfactants should have a significant relationship with the rate of penetration of pesticides.

• The Korean Journal of Pesticide Science
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• v.12 no.2
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• pp.127-133
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• 2008

The foliar uptake of dimethomorph into cucumber was assessed by spray application of aqueous dimethomorph solution containing fatty alcohol ethoxylate (FAE) or fatty acid alkyl ester as activator adjuvants. Afterward, the possible mechanism of action of FAE on foliar penetration of active ingredient was suggested by speculating on the effect of lipophile and hydrophile of FAEs. The amount of absorbed dimethomorph induced by polyoxyethylene mono-9-octadecenyl ether (6 moles ethylene oxide, $C_{18=9}E_6$) was linearly related to the concentrations of surfactant as well as dimethomorph in spray solution, suggesting that it is simply a diffusion phenomenon of the solute molecule through a cuticular membrane from leaf surface. Octadecanol attached to FAE was most effective lipophile on the leaf penetration of dimethomorph. And, the more ethylene oxide had the polyoxyethylene chain of FAE up to 20 moles, the higher the uptake rate was. Therefore, the role of lipophile of FAE on dimethomorph penetration to cucumber leaf, probably, is to modify the physico-chemical properties of cuticular membrane to be permeable to dimethomorph, and the polyoxyethylene chain having less than 20 moles ethylene oxide, which is moderately permeable to cuticular membrane by its molar volume, is to let the physically-modified cuticular membrane to be maintained for a longtime.

• Applied Biological Chemistry
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• v.51 no.2
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• pp.108-113
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• 2008

Azoxystrobin applied by aqueous WP suspension 50 mg/l was slightly absorbed into cucumber leaf in the absence of activator surfactant 24 h after spraying, but was increased to 25.7% by adding polyoxyethylene monohexadecyl ether (12 moles of ethylene oxide, CE-12) 500 mg/l. Only 4.1% of kresoxim-methyl WDG 100 mg/l in the absence of surfactant was absorbed into cucumber leaf 24 h after spraying, but was increased to 58.0% by adding polyoxyethylene monooctadecyl ether (14 moles of ethylene oxide, SE-14) 1,000 mg/l. The effect of CE-12 500 mg/l on foliar uptake of kresoxim-methyl at 50 mg/l was twice bigger than on azoxystrobin. Fungicidal activity of azoxystrobin WP against cucumber powdery mildew was marginally increased by adding surfactants to facilitate foliar uptake of azoxystrobin, so that the further increase of azoxystrobin uptake into cucumber plant by the addition of adjuvant was not a practical mean for enhancing the formulation efficacy in view of fungicidal activity. It was not possible for kresoxim-methyl to assess the adjuvant effect on the fungicidal activity in a greenhouse trial due to the vapor effect of active ingredient.

• Korean journal of applied entomology
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• v.43 no.4 s.137
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• pp.317-322
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• 2004

Insecticidal activity, systemic and residual effects, and effects on enzyme activities (esterase, acetylcholinesterase, glutathione S-transferase) of indoxcarb were evaluated against Plutella xylostella. The insecticide was very effective against larvae of P. xylostella. Also, indoxacarb showed only residual effect to P. xylostella when applied to vegetable leaves. It inhibited acetylcholinesterase activity, but didn't do esterase and glutathione S-transferase activities.

• Korean journal of applied entomology
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• v.26 no.1 s.70
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• pp.9-12
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• 1987

The control effect of three systemic insecticides on the brown planthopper; carbofuran 3G, disyston 3G, and omethoate 50% EC, which have been used to control of the insect pests on rice crop in its early growing season, were evaluated. Soil incorporation and water broadcasting methods before transplanation were used for carbofuran and disyston, and omethoate was applied as foliar spray 6 days after transplanation. Ten pairs of newly emerged adults were inoculated on June 11, 21, July 2, 11, and 25. The number of the brown planthoppers on the rice plane were examined by means of direct reading. The three insecticides were effective for about ten days regardless of application methods, thereafter, fail to control of the insects except carbofuran. By means of soil incorporation, carbofuran could control the insects effectively for 45 days or longer, and it seemed to be able to control the progeny of the migrated brown planthopper until middle or late June.

• The Korean Journal of Pesticide Science
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• v.11 no.4
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• pp.320-330
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• 2007

Mitochondrial 16S DNA sequences of Bemisia tabaci which were collected on rose greenhouse of Iwol and Jinchen in Chungbuk and red pepper field of Miryang, Gyeongnam, were analyzed. The mtCOI PCR product of B. tabaci collected on red pepper field of Miryang were digested with EcoT14I (Sty I) into two fragments 555bp and 311bp, while the PCR product of B. tabaci collected on rose greenhouse of Iwol were digested with Sty I into two fragments of 560bp and 306bp. As a result, B. tabaci collected on red pepper reveal biotype Q and those on rose greenhouse was biotype B. These was difference between two biotypes in insecticide susceptibility, and the biotype B was more susceptible than biotype Q. As a result of foliar systemic test, root-uptake systemic test and residual effect, the biotype B was more susceptible. In case of inhibition effect on enzyme activities of fenitrothion (organophosphorous) and fenothiocarb (carbamate), those of biotype Q was higher than those of biotype B. These results indicate that biotype Q was more resistant than biotype B against 12 insecticides.

• The Korean Journal of Pesticide Science
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• v.5 no.1
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• pp.46-54
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• 2001

These studies were carried out to investigate the toxicities of 33 registered insecticide to the American serpentine leafminer, Liriomyza trifolii. Insecticidal activities were evaluated by testing systemic action and residual effect in the laboratory, and control efficacy and phytotoxicity in the greenhouse. All insecticides used in this study did not effect on the egg of L. trifolii, although spinosad showed 70% of egg-hatch suppression. For L. trifolii larvae ($2{\sim}3$ instar), the insecticides with over 95% of insecticidal activity were abamectin, cartap, cyromazine, emamectin benzoate, diflubenzuron + chlorpyrifos. The Insecticide what showed over 90% of insecticidal activity or neonate larvae were abamectin, cartap, emamectin benzoate, diflubenzuron + chlorpyrifos and milbemectin. Only cartap + buprofezin showed over 95% insecticidal activity against L. trifolii pupae. Almost insecticides used in this study little or not effected on the adult of L. trifolii. Emamectin benzoate and milbemectin showed moderate foliar systemic effects on eggs of L. trifolii (53.3, 47.9%, respectively). However, other insecticides showed little systemic effect. For larvae and adults, all insecticides showed low systemic effects. Insecticides with over 90% residual effect for 10 days were abamectin, emamectin benzoate and milbemectin (91.4, 90.4, 91.9%, respectively). In the control efficacy test on L. trifolii 90% of control values were obtained at 14th day after treatment of the insecticides including abamectin, cyromazine, emamectin benzoate and milbemectin. Cartap and cartap + buprofezin showed slight phytotoxicity on kidney bean leaf, however, other insecticides showed no phytotoxic effects. These results indicate that abamectin, emamectin benzoate and milbemectin can be used for tile control of L. trifolii in field.

• Korean journal of applied entomology
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• v.57 no.3
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• pp.221-231
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• 2018

The susceptibility of the western flower thrips, Frankliniella occidentalis and garden thrips, Frankliniella intonsa was evaluated using 51 commercial insecticides. 15 kinds of insecticides which showed more than 90% mortality against both thrips, F. occidentalis and F. intonsa was selected. Many active ingredients were misused and abused in commercial mixture formulation insecticides. Since the F. intonsa was more susceptible than F. occidentalis, it was considered that both thrips can be controlled by insecticides that showed insecticidal activity on the F. occidentalis. Lethal time ($LT_{50}$ and $LT_{95}$), systemic toxicity and residual toxicity of selected insecticides were compared. Both chlorpyrifos WP and chlorpyrifos + diflubenzuron WP revealed the fastest toxicity within 2 h ($LT_{95}$), while spinetoram WG revealed the slowest toxicity as 62.3 h ($LT_{95}$). Chlorfenapyr SC showed toxicity at foliar and drenching application while spinetoram WG was toxic only in foliar application. Chlorfenapyr SC showed residual effect at 3, 5, 7, 10, 15 days after treatment and both benfuracarb WG and chlorpyrifos WP showed residual effect at 3 days after treatment. As a result of treatment of selected insecticides for field population of F. occidentalis, the population collected from horticultural crops showed lower susceptibility than the population collected from vegetable crops.