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1.
Two procedures are described for the determination of residues of triadimenol and compared on cereal material. After extraction, purification is carried out by Florisil column chromatography in method I and by semi-preparative High-Performance Liquid Chromatography in method II. Triadimenol residues are quantified by gas chromatography with a thermoionic detector. With method I, interference was observed but not with method II. This specific procedure has been tested on other plant materials. Recoveries in the range of 90–98% indicate that this procedure is suitable for residue analysis of this fungicide with detection limits of 0·008 mg kg?1 in wheat grains, 0·03 mg kg?1 in wheat straw and 0·004–0·008 mg kg?1 in other plants. Maximum residue limits in France are: 0·1 mg kg?1 in grain, 2·0 mg kg?1 in straw and 1·0 mg kg?1 in other vegetables and fruit.  相似文献   

2.
The simultaneous HPLC determination of clofentezine, fenoxycarb and hexythiazox in apples, pears and their pulps is described. The method is based on a clean-up procedure carried out on a Seppak C18 cartridge followed by HPLC analysis on an RP-18 column using acetonitrile + water as mobile phase. Average recoveries were 85.0% for clofentezine, 84.8% for fenoxycarb and 75.6% for hexythiazox on apple matrix; recoveries from pear matrix were in the same range. UV detection limits at 240 nm were 0.07 mg kg?1 for clofentezine, 0.064 mg kg?1 for fenoxycarb and 0.08 mg kg?1 for hexythiazox.  相似文献   

3.
The fungicides tebuconazole, tebuconazole + dichlofluanid, fenethanil, diethofencarb + carbendazim, and vinclozolin combined with chlorothalonil were tested for their ability to control grey mould (Botrytis cinerea Pers. ex Fr.) of cucumber and tomato grey mould in greenhouses under commercial conditions. In winter 1987/88 the number of diseased female fruits of cucumber (Cucumis sativus L.) was reduced by diethofencarb + carbendazim (2·5 mg dm?3 each) by 93% and by tebuconazole (2·5 mg dm?3)(phytotoxic when alone) or tebuconazole (1 mg dm?3) + dichlofluanid (4 mg dm?3) by 54–57%. Vinclozolin (5 mg dm?3) + chlorothalonil (25 mg dm?3) significantly reduced disease incidence on fruits by 40%. Infection foci on cucumber stems were significantly decreased by vinclozolin + chlorothalonil. A more pronounced decrease was obtained with diethofencarb + carbendazim, tebuconazole, or tebuconazole + dichlofluanid. During the season of winter 1988/89, tebuconazole + dichlofluanid (1·5 + 6 and 3 + 12 mg dm?3) and RH7592 (1 mg dm?3) significantly reduced diseased fruits by 30–71%. Grey mould of tomato (Lycopersicon esculentum Mill.) leaves was reduced by more than 90% and on fruits by 78–87% when tebuconazole + dichlofluanid (1·5 + 6 and 3 + 12 mg dm?3) or diethofencarb + carbendazim (2·5 mg dm?3 each) were applied. Yields of cucumber fruits of the common parthenocarpic cv. Kasem 292 were weighed. There was no correlation between disease level and yield in any experiment, plot or date except for two measurements. Compesation in fruit production by the plant may be regarded as the reason for no positive yield response to efficient control. The possibility of reducing fungicide application is discussed. Control of grey mould on tomato resulted in yield increase.  相似文献   

4.
The disappearance kinetics of the carbamate insecticide, carbosulfan, applied at 2 kg AI ha?1 (‘Marshal’ 250 g litre?1 EC) in peaches was studied. Degradation took place in two consecutive stages (0–28 and 28–57 days), with half-lives of 7.4 and 17.5 days, respectively. The residues obtained 57 days after treatment did not exceed 0.2 mg kg?1. When treatments were carried out 30, 21 and 14 days before the probable date of harvest (date of fruit maturation) with two doses (1.0 and 2.0 g formulated product litre?1) and two volumes applied (750 and 1500 litre ha?1), the residual levels detected were between 0.122 mg kg?1 (30 days before harvest) and 0.4 mg kg?1 (14 days before harvest). The major metabolite, carbofuran, was never detected above its determination limit of 0.004 mg kg?1 throughout the whole study.  相似文献   

5.
The long-term fate of the acaricide, fenbutatin oxide, in soil has been investigated. Residues of the compound and its two principal metabolites have been determined in soil samples obtained from citrus orchards in Italy and Spain where the product had been applied commercially over a period of 6–10 years. The average fenbutatin oxide content in the upper 0–15 cm soil layer ranged from ? 1 mg kg?1 to 5 mg kg?1 in sites receiving single and double applications per year. The residues were located primarily (> 95%) in the top 0–30 cm layer and there was virtually no movement of the compound through the soil to lower depths. Below 0.5 m depths, the sites contained average concentrations of ? 0.01 mg kg?1, the limit of determination. No significant build-up of residues was observed and the data indicate an approximate half-life in soil of just less than one year. Residues of the two metabolites, dihydroxy-bis(2-methyl-2-phenylpropyl)stan-nane and 2-methyl-2-phenylpropyl stannonic acid, were on average 11% and 16% of the fenbutatin oxide concentration, respectively. As with fenbutatin oxide, there was no significant movement through the soil to lower levels.  相似文献   

6.
A procedure has been developed for the determination of iron(III) dimethyldithiocarbamate by converting it into iron(III)- bathophenanthroline complex, which is then dissolved in water in the presence of sodium dodecyl sulphate as a surfactant, and the absorbance measured at 532 nm against a reagent blank. Beer's law is obeyed over the concentration range 0.3–20 µg ml−1 in the final solution. The method is sensitive, highly selective and can be used for the determination of ferbam in a commercial sample, in mixtures with various dithiocarbamates (ziram, zineb, maneb, etc.) and from wheat grains. © 1999 Society of Chemical Industry  相似文献   

7.
The study deals with the effect of common, annually-used pesticides on soil microorganisms, pesticide residues in soil, and carrot (Daucus carota) yields in Central Finland. Linuron residues in carrot roots were also analysed. Thiram+lindane and dimethoate were applied from 1973–1981 at the commercially recommended doses on experimental plots of carrots, linuron was applied at twice the recommended rate from 1973–1979 and at the normal rate thereafter and in addition TCA was applied in 1978. Maleic hydrazide was used in the years 1973–1976, and glyphosate after 1977. The numbers of different soil microorganisms, their activities and the pesticide residues were studied from autumn 1978 to 1981. The pesticide treatments reduced the growth of soil algae but increased the total number of microorganisms and the number of aerobic spore-forming bacteria. Linuron residues in the soil were 0.9–2.8 mg kg?1 in the growing season and 1.2–1.7 mg kg?1 in the autumn, 3 months after application. The residues of glyphosate in the soil were 0.7 mg kg?1 in the autumn, 41 days after the treatment, and had declined to a level of about 0.2 mg kg?1 by the following summer. In the pesticide-treated plots the carrot yield was only 20–60% of the yield in the hand-weeded plots. The herbicide programme controlled most of the annual weeds but not couchgrass Elymus repens and milk sow-thistle Sonchus arvensis.  相似文献   

8.
In laboratory experiments, whole wheat was treated with pirimiphos-methyl or carbaryl or combinations of these two insecticides; the treated grain was then adjusted to a 12% moisture content and stored at 25°C for bioassay at various intervals over a period of 39 weeks. Pirimiphos-methyl at 5.1 mg kg?1 effectively controlled Sitophilus granarius (L.) and Tribolium confusum Jacquelin du Val but was ineffective against Rhyzopertha dominica (F.) CRD 118, a strain showing malathion resistance. Conversely, carbaryl at 6.5 mg kg?1 (but not at 3.1 mg kg?1) was effective against R. dominica, but ineffective against the other two species. A combination of pirimiphosmethyl + carbaryl, at 1.8 + 5.1 mg kg?1, controlled S. granarius and R dominica but not T. confusum, whilst a 4.2 + 3.4 mg kg?1 combination was relatively more effective against T. confusum but less so against R. dominica. In a separate experiment, whole wheat was treated with carbaryl at 2.5, 5.0 and 7.5 mg kg?1 (nominal rates). Samples were stored and, at various times after the treatments, were bioassayed with R. dominica CRD 2, at 20, 25, 30 and 35°C. The results were comparable with those for the CRD 118 strain, but efficacy was reduced at higher temperatures. The combination of pirimiphos-methyl at 4–5 mg kg?1 and carbaryl at 5–6 mg kg?1 is suggested as a potentially useful grain protectant where R. dominica is a problem and long term storage is required. These results are discussed in relation to the protection of stored grain in Australia.  相似文献   

9.
A gas chromatographic method, using electrolytic conductivity detection, is presented for the determination of 2,4-0 as its methyl ester in triticale (X Triticosecale Wittmack). The method was used to monitor the dissipation of 2,4-0 residues in triticale over a growing season at two sites following post-emergence application of the dimethylamine salt of 2,4-D at 0.56 kkg ha?1. Initial residues, in the order of30 mg kg?1. on the day afer application (3- to 4-leaf stage of the crop), decreased to non-detectable levels in the mature straw and seed. Recoveries of 2,4-D were greater than 90% fiom green tissue fortified at 0.1 mg k?1., and in the order of 75% from seed fortified at 0.05 mg kg?1.  相似文献   

10.
Field trials with various pesticide combinations were carried out on bulk wheat in commercial silos in Queensland, South Australia and Western Australia. Laboratory bioassays on samples of treated grain at intervals over 8 months using malathion-susceptible and malathion-resistant strains established the following orders of efficacy: against Sitophilus oryzae (L.), chlorpyrifos-methyl 10 mg kg?1 + bioresmethrin 1 mg kg?1 = methacrifos 15 mg kg?1 in aerated storage > pirimiphos-methyl 4 or 6 mg kg?1 + bioresmethrin 1 mg kg?1 = bioresmethrin 4 mg kg?1 + piperonyl butoxide 16 mg kg?1; against Rhyzopertha dominica (F.), bioresmethrin 4 mg kg?1 + piperonyl butoxide 16 mg kg?1 > methacrifos 15 mg kg?1 > chlorpyrifos-methyl 10 mg kg?1 + bioresmethrin 1 mg kg?1 = pirimiphos-methyl 4 or 6 mg kg?1 + bioresmethrin 1 mg kg?1. All treatments completely prevented production of progeny in Sitophilus granarius (L.), Tribolium castaneum (Herbst), T. confusum Jackquelin du Val and Oryzaephilus surinamensis (L.). The biological efficacy of methacrifos was greater and the rate of degradation lower in aerated than in non-aerated storage. Residue levels of all compounds were determined chemically and were below proposed international residue levels to be considered by the Codex Alimentarius Commission.  相似文献   

11.
BACKGROUND: The parasitoid Trichogramma ostriniae (Pang and Chen) is a major natural enemy of many lepidopterans, but only a few studies have been conducted on the compatibility of biological and chemical controls. In this study, the selectivity of 30 insecticides to T. ostriniae adults was evaluated. RESULTS: Among the seven classes of chemicals tested, organophosphates and carbamates had the highest intrinsic toxicity to the wasp, with LC50 values ranging from 0.032 (0.029–0.038) to 2.38 (1.91–3.15) mg AI L?1. They are followed by phenylpyrazoles, avermectins, neonicotinoids and pyrethroids, which induce variable toxicity responses, with LC50 values ranging from 0.14 (0.11–0.21) to 56.67 (48.94–67.24) mg AI L?1, from 2.57 (1.85–4.28) to 4.48 (3.34–6.83) mg AI L?1, from 2.48 (1.80–4.03) to 503.6 (457.6–557.5) mg AI L?1 and from 5.44 (3.95–8.84) to 104.2 (92.48–119.7) mg AI L?1 respectively. The insect growth regulators (IGRs) exhibited least toxicity to the parasitoid. CONCLUSION: Risk quotient analysis classifies neonicotinoids, avermectins, pyrethroids, IGRs and phenylpyrazoles (with the exception of butane‐fipronil and fipronil) as safe agents to the parasitoid, but categorises organophosphates and carbamates as slightly to moderately toxic or dangerous to T. ostriniae. Copyright © 2012 Society of Chemical Industry  相似文献   

12.
During subacute toxicological testing of PYR-VU-TO2, a novel cypermethrin-like pyrethroid with a high (150:1) cis: trans ratio, its distribution in skeletal muscle and internal organ tissues of two groups of experimental sheep was investigated after oral administration of two different doses (1/10 and 1/20 of the LD10). Residual levels of PYR-VU-TO2 were also observed in sheep blood after administration of a single dose of the compound. Homogenized internal organ tissues and blood samples were extracted in light petroleum distillate+acetone for 15 min. After filtration, the extract was cleaned up on a ‘Florisil’R and sodium sulfate layer. The pyrethroid elution was processed with acetone+light petroleum distillate (2+98 by volume). Recoveries ranged from 80.7 to 93.5%. Unchanged PYR-VU-TO2 residues were determined on a 1.5-m stainless steel packed column under isothermal conditions with an electron-capture detector. The results were evaluated by the calibration curve method. The coefficients of variation were generally lower than 5% and determination limit for PYR-VU-TO2 was 20 μg kg?1. Mean unchanged PYR-VU-TO2 residues lay within a wide range. After six weeks of treatment the following order of tissue residue levels could be stated: heart>lung>muscle>spleen>kidney>liver>brain, and spleen>muscle>lung>heart>liver>kidney>brain for experimental groups I and II, respectively. Only small differences between the residues in the tissues of males and females were found in the first group (daily PYR-VU-TO2 dose of 50 mg kg?1 live weight). The experimental females of the second group (daily PYR-VU-TO2 dose of 200 mg kg?1 body weight) revealed higher levels (other than spleen) than did the males. Maximum PYR-VU-TO2 residues in sheep blood were found 24 h after administration of a single dose. Confirmation of the results was carried out by determination of 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid methyl ester by capillary GC.  相似文献   

13.
In order to obtain residue data from the application of the algicide endothal in Italian rice paddy fields, two experiments were carried out using a 50 g kg?1 granular formulation in a small pond and the same granular and two liquid formulations in actual paddy fields of the Italian rice growing area. Endothal decay in the pond water was very rapid, reaching residue levels of 0·01-1·02 mg litre?1 in two days and 0·004-0·01 mg litre?1 at the third day. The muddy soil of the pond was free from measurable endothal residues( <0·02 mg kg?1). In the paddy-field waters, the endothal decay was slower, with an average half-life time of 3·3 days, independently of the type of formulation. The actual residues in water after 6 days ranged from 0·3 to 1·3 mg litre?1 according to the initial amount of product applied, and, consequently, to the initial concentration in water. Rice samples collected at the normal harvest time from the two paddy fields, treated with three different formulations, showed no endothal residue at the minimum detectable level of 0·01 mg kg?1.  相似文献   

14.
Duplicate field trials were carried out on bulk wheat in commercial silos in Queensland and New South Wales. Laboratory bioassays on samples of treated grain at intervals over 9 months, using malathion-resistant strains of insects, established that treatments were generally effective. Fenitrothion (12 mg kg?1)+ (1R)-phenothrin (2 mg kg?1) was more effective than pirimiphos-methyl (6 mg kg?1) + carbaryl (10 mg kg?1) against Sitophilus oryzae (L.) and Ephestia cautella (Walker); the order of effectiveness was reversed for S. granarius (L.). Against Rhyzopertha dominica (F.), Tribolium castaneum (Herbst), T. confusum Jackquelin du Val and Oryzaephilus surinamensis (L.), both treatments effectively prevented the production of progeny. The order of persistence was pirimiphos-methyl> (1R)-phenothrin>carbaryl or fenitrothion. During processing from wheat to white bread, residues were reduced by 98% for carbaryl, >44% for (1R)-phenothrin, 98% for fenitrothion and 85% for pirimiphosmethyl.  相似文献   

15.
A spectrophotometric method has been developed for the determination of ziram (zinc bis(dimethyldithiocarbamate)) and zineb (zinc ethylenebisdithiocarbarnate) by converting these into a zinc-4-(2-pyridylazo)resorcinol complex, which is dissolved in acetone and water and the absorbance measured at 490 nm against a reagent blank. Beer's law is obeyed over the concentration ranges 0.025-1.25 and 0.025-1.5 mg litre?1 for ziram and zineb respectively in the final solution. The method is sensitive and can be used for the direct determination of ziram and zineb in commercial formulations, grains (rice and wheat) and synthetic mixtures (in the presence of various other dithiocarbamates). The limit of determination of ziram and zineb from foodstuffs in 0.2 mg kg ?1.  相似文献   

16.
Pyriproxyfen, a novel juvenile hormone mimic, is a potent suppressor of embryogenesis and adult formation of the sweetpotato whitefly, Bemisia tabaci (Gennadius), and the greenhouse whitefly, Trialeurodes vaporariorum (Westwood). Dipping of cotton or tomato seedlings infested with 0 to 1-day-old eggs in 0.1 mg litre?1 resulted in over 90% suppression of egg hatch of both B. tabaci and T. vaporariorum. Older eggs were affected to a lesser extent. Exposure of whitefly females to cotton or tomato seedlings treated with pyriproxyfen resulted in oviposition of non-viable eggs. The LC90 values for egg viability of B. tabaci and T. vaporariorum exposed to treated plants were 0.05 and 0.2 mg litre?1, respectively. Treatment of whitefly larvae with 0.04–5 mg litre?1 resulted in normal development until the pupal stage; however, adult emergence was totally suppressed. Second instars of B. tabaci exposed to 5 mg litre?1 pyriproxyfen, excreted honeydew at a level similar to the control level until the fourth instar (pupation), after which a strong reduction was observed. Inhibition of egg-hatch on the lower surface of cotton leaves was observed when their upper surface was treated with 1–25 mg litre?1, indicating a pronounced translaminar effect. These findings indicate that pyriproxyfen is an efficient control agent of both B. tabaci and T. vaporariorum. The compound has been used successfully for controlling whiteflies in Israeli cotton fields since 1991. Adults of B. tabaci collected from a rose greenhouse and from adjacent cotton fields were monitored during 1991–1993 for their susceptibility to pyriproxyfen. A high level of resistance was recorded in whiteflies collected from a greenhouse after three successive applications of pyriproxyfen. Based on LC50 values, the resistance ratio for egg-hatch suppression was 554-fold and, for adult emergence failure, 10-fold. However, a single treatment of pyriproxyfen in cotton fields during the summer season (according to an insecticide resistance management (IRM) strategy) did not alter appreciably the susceptibility of B. tabaci to this compound. In order to prevent development of resistance, an attempt should be made to restrict its use to one treatment per crop season applied during the peak activity of the pest. Pyriproxyfen can be alternated with other novel compounds such as buprofezin and diafenthiuron for controlling whiteflies in cotton, vegetables and ornamentals as part of integrated pest management (IPM) and IRM strategies. In pyriproxyfen- or buprofezin-resistant strains of B. tabaci or T. vaporariorum, no appreciable cross-resistance was observed among pyriproxyfen, buprofezin and diafenthiuron.  相似文献   

17.
Sorghum (Sorghum bicolor (L.) Moench) plants were grown in pots with 12.5 and 50 mg applied N kg?1 soil. With an increase of soil N, the Striga asiatica (L.) Kuntze infestation, as well as the sorghum shoot dry matter losses due to infestation, decreased. The relative differences in stimulant capacity to induce Striga seed germination among the four sorghum genotypes were not consistent over the 0 to 150 mg N 1?1 range. The sorghum root exudate was considerably more active at 0 mg N 1?1, than at 30 mg N 1?1, and the stimulant produced at 150 mg N 1?1 failed to induce Striga seed germination. Presence of N in the growth medium considerably reduced the effectiveness of the stimulating substance produced by sorghum roots, whereas K promoted stimulant activity only in the absence of N. The presence or absence of P in the growth medium did not affect Striga seed germinability, probably due to the inability of this element to interfere with the production or activity of the stimulating substance from the host plants. It can be concluded, therefore, that sorghum plants seem to produce active root exudate only in conditions of N deficiency.  相似文献   

18.
The build-up and decline of quintozene and hexachlorobenzene residues in protected lettuce, resulting from one to five treatments of the soil (each of 35 g m-2) with a quintozene formulation, have been studied. Residue levels were monitored in each experimental crop during growth until harvest. Residues in the soil at harvest were also determined. Quintozene residues in the harvested lettuce were in the range < 0.02–0.80 mg kg?1 and those of hexachlorobenzene were in the range < 0.02–0.05 mg kg?1 (expressed on a fresh weight basis). Residue levels in the soil were 5.4–231 mg kg?1 for quintozene, and 0.20–5.4 mg kg?1 for hexachlorobenzene (expressed on a dry weight basis). Under the experimental conditions of the trial there was no significant build-up of quintozene or hexachlorobenzene in harvested lettuce, even after five treatments to the same site.  相似文献   

19.
Various control strategies for Achillea millefolium L. (yarrow) were investigated in a dense stand of the weed at Lincoln College in 1977–1978. In early spring plots were either rotary cultivated or left undisturbed. In late spring, plots of both previous treatments were either left undisturbed, rotary cultivated or sprayed with glyphosate at 1·5 kg ha?1. The whole experiment was rotary cultivated twice 1 week later and sown with Hordeum vulgure L. cv. Zephyr (barley) at 144 kg seed ha?1. MCPA + dicamba at 0·9+0·15 kg ha?1 was applied to half of each plot when the second node was detectable (Zadok 32). Rotary cultivation and glyphosate both substantially reduced the regrowth of A. millefolium but glyphosate reduced regrowth by a greater proportion when applied to undisturbed plants than when applied to plants regenerating after cultivation. Both gave a more than 95% reduction compared to the control (rotary cultivation only at sowing time) in the amount of A. millefolium present in the barley stubble in the autumn. MCPA + dicamba caused seedling mortality but did not affect the numbers of primary shoots from rhizome fragments. The grain yield of the barley increased from 2·91 t ha?1 when A. millefolium was not controlled to 4·23 t ha?1 with good control. The barley yield appeared to be restricted by competition from regenerating A. millefolium and by a nitrogen deficiency induced in some regimes by nitrogen immobilization in decaying rhizomes.  相似文献   

20.
Organophosphorus insecticide residues have been monitored for two years in virgin olive oil after dimethoate and fenthion treatments to control the olive fruit fly. No dimethoate residues were detected in any of the samples. For the first and second years, 50% and 21%, respectively, of the samples contained no detectable fenthion residues, while 4% and 6%, respectively had residue concentrations exceeding the Codex Alimentarious Maximum Residue Limit (1 mg kg?1). The mean concentration was 0·236 mg kg?1 oil and the estimated daily intake of fenthion 0·0002 mg kg?1 body weight (Acceptable Daily Intake 0·001 mg kg?1 body weight). The parent compound was the most important residue in fresh samples, while aged samples contained a higher amount of the metabolite fenthion sulfoxide. The contribution of the oxygen analogues (P= 0 metabolites) of fenthion to the total residue concentration was<5% in most cases.  相似文献   

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