首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 390 毫秒
1.
Permethrin and deltamethrin, two synthetic pyrethroid insecticides, are registered in several countries for use on lettuce. Both chemicals were applied on autumn and spring grown lettuce in the glasshouse. When applied at the normal prescribed dose rates of 25 and 12.5 g a.i. ha?1, < 1 mg kg?1 of either compound was found in the lettuce at harvest, even when applied only a few days before harvest. The total amount of active ingredient applied was too low to reach the 1 mg kg?1 level when evenly applied on marketable lettuce heads weighing about 200 g each. Applying a higher dose than 25 g permethrin a.i. ha?1 or 12.5 g deltamethrin a.i. ha?1, or applying two applications in the 2 weeks prior to harvest, may well result in residue levels higher than the maximum residue limit of 1 mg kg?1 for permethrin and certainly higher than the maximum residue limit of 0.2 mg kg?1 for deltamethrin, which is more persistent.  相似文献   

2.
BACKGROUND: A mixture of trifloxystrobin and tebuconazole is excellent in controlling both powdery and downy mildew of grapes. The objective of the present work was to study the behaviour of trifloxystrobin and tebuconazole on grape berries and soil following treatment with Nativo 75 WG, a formulation containing both fungicides (trifloxystrobin 250 + tebuconazole 500 g kg?1). This study was carried out for planned registration of this mixture for use on grapes in India. RESULTS: Initial residue deposits of trifloxystrobin and tebuconazole on grapes were below their maximum residue limit (MRL) of 0.5 and 2 mg kg?1, respectively, when Nativo 75 WG was applied at the recommended dose of 175 g product ha?1. The residues dissipated gradually to 0.02 and 0.05 mg kg?1 by 30 days, and were below the quantifiable limit of 0.01 mg kg?1 at the time of harvest (60 days after the last treatment). Trifloxystrobin and tebuconazole dissipated at a pre‐harvest interval (PHI) of 36 and 34 days, respectively, from the recommended treatment dose. The acid metabolite of trifloxystrobin, CGA 321 113, was not detected in grape berries at any point in time. Soil at harvest was free of any pesticide residues. CONCLUSION: Residue levels of both trifloxystrobin and tebuconazole were below MRLs when grapes were harvested 30 days after the last of four applications of 175 g product ha?1 (trifloxystrobin 44 g AI ha?1, tebuconazole 88 g AI ha?1) under the semi‐arid tropical climatic conditions of India. Copyright © 2010 Society of Chemical Industry  相似文献   

3.
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   

4.
Blackcurrants, treated with 0.1 kg of 2,4,5-T ha?1 (as esters of mixed C4–C6 alcohols; ‘Tormona 80’), contained 0.1 mg of 2,4,5-T residues kg?1 in the berries at ripeness 29 days after treatment. Total residues in the berries were not reduced during growth and ripening, although the residue concentrations declined in the same period due to growth dilution. In spinach leaves from old plants, treated with 0.1 kg ha?1, 0.05 mg of 2,4,5-T kg?1 was found 14 days after treatment. Fodder peas showed no residues (< 0.002 mg kg?1) at harvest 62 days after treatment with 2,4,5-T esters. After application of 0.1 kg ha?1 on potato plants, the disappearance of 2,4,5-T was rapid during the first month, but residues were translocated into the tubers and reached a constant level of 0.02 mg kg?1 after 1 month until harvest at 108 days after treatment. In all crops, visible effects were observed after treatment with 0.1 kg ha?1. After the application at 0.01 kg ha?1, phytotoxic effects were observed only in blackcurrants, but negligible residues were found in all the test crops.  相似文献   

5.
The depletion of zeta‐cypermethrin residues in bovine tissues and milk was studied. Beef cattle were treated three times at 3‐week intervals with 1 ml 10 kg?1 body weight of a 25 g litre?1 or 50 g litre?1 pour‐on formulation (2.5 and 5.0 mg zeta‐cypermethrin kg?1 body weight) or 100 mg kg?1 spray to simulate a likely worst‐case treatment regime. Friesian and Jersey dairy cows were treated once with 2.5 mg zeta‐cypermethrin kg?1 in a pour‐on formulation. Muscle, liver and kidney residue concentrations were generally less than the limit of detection (LOD = 0.01 mg kg?1). Residues in renal‐fat and back‐fat samples from animals treated with 2.5 mg kg?1 all exceeded the limit of quantitation (LOQ = 0.05 mg kg?1), peaking at 10 days after treatment. Only two of five kidney fat samples were above the LOQ after 34 days, but none of the back‐fat samples exceeded the LOQ at 28 days after treatment. Following spray treatments, fat residues were detectable in some animals but were below the LOQ at all sampling intervals. Zeta‐cypermethrin was quantifiable (LOQ = 0.01 mg kg?1) in only one whole‐milk sample from the Friesian cows (0.015 mg kg?1, 2 days after treatment). In whole milk from Jersey cows, the mean concentration of zeta‐cypermethrin peaked 1 day after treatment, at 0.015 mg kg?1, and the highest individual sample concentration was 0.025 mg kg?1 at 3 days after treatment. Residues in milk were not quantifiable beginning 4 days after treatment. The mean concentrations of zeta‐cypermethrin in milk fat from Friesian and Jersey cows peaked two days after treatment at 0.197 mg kg?1 and 0.377 mg kg?1, respectively, and the highest individual sample concentrations were 2 days after treatment at 0.47 mg kg?1 and 0.98 mg kg?1, respectively. © 2001 Society of Chemical Industry  相似文献   

6.
Petroleum spray oil (2, 4 and 6% in water) was applied to Valencia orange, Citrus sinensis (L.) Osbeck, for the control of Chinese wax scale, Ceroplastes sinensis del Guercio, using a low-volume ( <2000 litre ha?1)air-blast (LV AB) sprayer, a low- to high-volume (L-HV) (up to 7000 litre ha?1) sprayer with four fan-assisted rotary atomiser (FARA) spray heads mounted on a vertical tower, and a high-volume (>7000 litre ha?1) oscillating boom (HV OB) sprayer. The most effective sprayer was the L-HV FARA sprayer. The most cost-effective treatment was a 20 ml litre?1 (60 litre oil ha?1) spray applied at 3000 litre ha?1 by the L-HV FARA sprayer. It gave mortality equivalent to a standard 20 ml litre?1, 10 700 litre ha?1 spray (214 litre oil ha?1) applied by the HV OB sprayer but with 72% less spray and significantly less oil deposited per cm2 of leaf area. Equivalent or significantly (P = 0·05) higher mortality than that given by the 10 700 litre ha?1 HV OB spray was given by the 40 ml litre?1, 3000 (120 litre oil ha?1) and 60 ml litre?1, 2180 and 3000 litre ha?1 (130·8 and 180 litre oil ha?1) L-HV FARA sprays, but the 60 ml litre?1 sprays deposited more oil per cm2 than the 20 ml litre?1 HV OB spray and were considered to be potentially phytotoxic. The least effective sprayer was the LV AB sprayer, which applied a 60 ml litre?1 spray (57·6 litre oil ha?1) at 960 litre ha?1. Linear relationships were established for Chinese wax scale mortality, transformed using an angular transformation (arcsin proportion), versus log10 spray volume for the 20, 40 and 60 ml litre?1 sprays applied by L-HV FARA at 1260,2180 and 3000 litre ha?1, mortality versus log10 μg oil cm?2 and log10 μg oil versus log10 volume of oil sprayed.  相似文献   

7.
Foliar applications of synthetic pyrethroids were made to several crops to determine residue levels at various intervals after application. On onions, residues of cypermethrin, permethrin and fenvalerate were negligible > 0.1 mg kg?1, 7 days after application. On lettuce, residues of fenvalerate and permethrin were 0.8 mg kg?1. On celery, residues of fenvalerate did not decline and ranged from 0.12 to 0.25 mg kg?1 during the 14-day period. On green bush-beans, residues of permethrin and cypermethrin did not decline during the 14-day period and ranged from 0.1 to 0.6 mg kg?1. By day 7, residues of cyfluthrin, cypermethrin, deltamethrin, fenvalerate and permethrin on strawberries were less than the acceptable maximum tolerance of 0.1 mg kg?1 with the exception of cypermethrin, applied at the rate of 0.14 kg a.i. ha?1 which gave a residue of 0.14 mg kg?1.  相似文献   

8.
The effects of two herbicides, glyphosate (as a 359 g litre?1 SL) and hexazinone (as a 50gkg?1 granule) on soil microbial population, carbon dioxide evolution, and in-vitro growth of five species of ectomycorrhizal fungi were investigated. Glyphosate at 0–54 and 3.23 kg a.i. ha?1 and hexazinone at 1. 2 and 8 kg a.i. ha?1 did not reduce soil microbial population or carbon dioxide evolution in the long term (6 months). However, there was a significant short-term (2 months) effect of glyphosate on both fungal and bacterial counts at the 0.54 kg ha?1 treatment. In in-vitro tests, Cenococcum graniforme. Hebeloma crustuliniforme and Laccaria laccata were more susceptible to both herbicides than was Suillus tomentosus. which was, in turn, more susceptible than Paxillus involutus. The growth of all five ectomycorrhizal fungi was significantly reduced when subjected to concentrations above 50 μl formulation litre?1 (glyphosate) or 50 μg formulation litre?1 (hexazinone).  相似文献   

9.
Following experimental and commercial applications to soil of a granular formulalation of phorate (O,O-diethyl S-ethylthiomethyl phosphorodithioate), residues in the soil and in lettuce were determined by gas-liquid chromatography. When applied by the bow-wave method as a continuous logarithmically-changing dose ranging from approximately 0.9 to 16.0 kg a.i. ha?1, the proportional rate of oxidation in soil of phorate sulphoxide to phorate sulphone was inversely related to dose. Ten weeks after application, total phorate residues in the soil had declined by about 35% at all dose levels. Residues in mature lettuce, from the 1-5 kg ha?1 dose-range, comprised the parent and oxygen analogue sulphoxides and sulphones; the relative proportions of the individual metabolites were independent of dose. Over this dose-range, total residue concentrations in the crop became proportionally slightly greater with increasing dose. When single doses of 1.1, 2.0 or 2.2 kg a.i. ha?1 were applied at drilling, the total residue concentrations in the lettuce declined from 5 mg kg?1 in seedlings from some treatments to <0.05 mg kg?1 at harvest. In plants raised in peat blocks containing 10 or 20 mg a.i. per block, however, residues in seedlings totalled 45-47 mg kg?1 and declined to only 0.7 mg kg?1 at harvest. It was concluded that bowwave applications of phorate when field-sowing lettuce were unlikely to lead to unacceptable residues in the harvested crop, but that residues in lettuce raised in phorate-treated peat blocks may be unacceptably high.  相似文献   

10.
A method is described for the analysis of small amounts of hydrazine in maleic hydrazide formulations. Following derivative formation with pentafluorobenz-aldehyde, the pentafluorobenzaldehyde azine was extracted with hexane and determined by gas-liquid chromatography with electron-capture detection. Recoveries of 72-80% were obtained from samples fortified with 1 and 10 μg of hydrazine. The limit of detection was 0.05 mg kg?1. Fourteen commercial formulations with maleic hydrazide concentrations ranging from 180-360 g litre?1 were investigated. The hydrazine content of the maleic hydrazide used in these formulations ranged from less than 0.05 to 53 mg kg?1. During the storage of two samples at 50°C for 10 weeks, the hydrazine contents increased from 2.2 to 124 and 0.4 to 54 mg litre?1, respectively.  相似文献   

11.
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   

12.
The mobility and decomposition of the herbicide fluroxypyr (4-amino-3,5-dichloro-6-fluoro-2-pyridyloxyacetic acid) was studied under field conditions in a sandy soil and a clay soil. Leachate was collected in lysimeters with undisturbed soil (sand) and in tile-drained plots (clay). Soil samples to a depth of one metre were also collected in both soils to characterize the temporal depth distribution of fluroxypyr in the profiles. The herbicide was applied as the I-methylheptyl ester of fluroxypyr at two rates, 187.5 and 375.0 g a.e. ha?1, representing the normal and double the dose of the compound used for spring cereals. Some lysimeters received supplementary watering. Only two leachate samples (one from each soil) had concentrations of fluroxypyr above the detection limit (1 μg litre?1), i.e. 2 and 5 μg litre?1. Both samples were collected within two months after application, when less than 2 mm of drainage had been collected. The methylheptyl ester of fluroxypyr was not found in any of the samples. Fluroxypyr levels above the detection limit in soil (5 μg kg?1 dry soil), were never found below the topsoil (0.2 m) in the clay profile, while, in the sandy profile, levels just above the detection limit were found occasionally in deeper soil layers. Concentrations were reduced to undetectable or very low levels within three months after spraying.  相似文献   

13.
The chitin synthesis inhibitor diflubenzuron, applied as a wettable powder spray to woven polypropylene at 100–500 mg m?2, was effective against Dermestes maculatus De Geer for at least 12 weeks. D. maculatus was unable to develop on ox hide dipped in a suspension of diflubenzuron (125 mg litre?1), or on fishmeal dusted at 1–10 mg of active ingredient kg?1. Diflubenzuron prevented the development of infestations of Callosobruchus maculatus (L.) on peas and of Acanthoscelides obtectus (Say) on beans dusted at 1–5 mg kg?1. The compound was also very effective against early instar larvae of Trogoderma granarium Everts on wheat. The persistence and activity of diflubenzuron at low dosage rates against D. maculatus appear to justify larger scale trials.  相似文献   

14.
M. ANDREWS 《Weed Research》1990,30(5):331-340
Avena saliva cv. Amuri and A. fatua were sprayed with diclofop methyl (1.0 kg a.i. ha?1) alone and in combination with 2,4-D (1.1 kg a.i. ha?1), bentazone (1.0 kg a.i. ha?1), chlorsulfuron (15 g a.i. ha?1) or dicamba (0.3 kg a.i. ha?1). Effects of the herbicides on leaf extension rate during the first 8 to 10 days after spraying and subsequent growth (dry weight) after 57–75 days were determined by comparison with unsprayed plants. Diclofop-methyl applied alone did not cause a decrease in leaf extension rate of A. saliva or A. fatua until at least 4 days after spraying. All broadleaf weed herbicides in combination with diclofop-methyl caused a decrease in leaf extension rate of both species within 2 days of spraying. Ten days after spraying, leaf extension rates for plants sprayed with a broadleaf weed herbicide plus diclofopmethyl (all combinations) were lower than for unsprayed plants but greater than for plants sprayed with diclofop-methyl alone. With the exception of A. fatua sprayed with bentazone, long-term growth of plants sprayed with a broadleaf weed herbicide plus diclofop-methyl (all combinations) was lower than for unsprayed plants but greater than for plants sprayed with diclofop-methyl alone. Bentazone applied with diclofop-methyl caused a substantial decrease in leaf extension rate of A. fatua within 24 h of spraying but at harvest, dry weight of plants from this treatment was similar to or less than that for plants sprayed with diclofop-methyl alone. Application of diclofop-methyl with bentazone at a rate of 0.3 kg a.i. ha?1 also caused a reduction in leaf extension rate of A. fatua within one day of spraying. At this rate of bentazone, dry weight of plants at harvest was intermediate to that of unsprayed plants and those sprayed with diclofop-methyl alone. It is proposed that decreased leaf expansion rate during the first few days afte spraying is the cause of broadleaf weed herbicide antagonism of diclofop-methyl.  相似文献   

15.
Ephestia elutella larvae in diapause were exposed at 25°C to methyl bromide at 12 mg litre?1 for 3.5 or 7.5 h and then immediately exposed to a lower concentration. The minimum effective concentration (that at which Haber's rule, concentration × time = k, a constant for mortality, still applied) was about 3 mg litre?1 in tests with no previous exposure toa high concentration, but it was about 2.5 mg litre?1 for individuals surviving a 3.5 h exposure to 12 mg litre?1, and was about 1.6 mg litre?1 for those surviving a 7.5 h exposure to 12 mg litre?1. These exposures to 12 mg litre?1, respectively, killed 2–20% and 50–75% of larvae exposed, and hence the smaller the proportion of survivors of exposure to a high concentration, the lower the minimum effective concentration needed against them. Thus the low concentration persisting at the end of a practical fumigation should contribute significantly to the success of the treatment and be much more effective than any similar low concentration present soon after the introduction of gas.  相似文献   

16.
Pesticide movement to subsurface drains was monitored in two typical crop production areas in Germany. Field trials were conducted on two subsurfacedrained soils, a silt loam and a poorly structured sandy soil, under different climatic conditions. Over a period of one year, the drainflow was measured and the drain water was analysed for all applied herbicides. Different leaching behaviour was observed at the two field sites. Following autumn application of pendimethalin and isoproturon to the Soester Börde soil, maximum concentrations of about 62 μg litre?1 for isoproturon and 0.7 μg litre?1 for pendimethalin were observed in drainflow from this silt loam. The early occurrence of both herbicides in the drain water only two days after application is consistent with fast flow through macropores. In contrast, on the subsurfacedrained sandy soil in Brandenburg, isoproturon did not reach the drains until two months after autumn application and was found at maximum concentrations of only 1.4 μg litre?1; pendimethalin was not detected in the drain water. Pesticide movement after spring application seemed to be of minor importance. At both locations, spring application led to low concentrations of pesticides in the drainflow (pendimethalin < 0.01 μ litre?1; metolachlor ? 0.05 μ litre?1; chloridazon ? 0.15 μ litre?1; metamitron ? 0.02 μg litre?1; terbuthylazine ? 1.4 μ litre?1).  相似文献   

17.
BACKGROUND: The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is a cosmopolitan insect pest of citrus and vectors the bacterium Candidatus Liberibacter asiaticus, a suspected causal organism of citrus greening or ‘huanglongbing’ disease. Aldicarb 150 g kg?1 GR (Temik® 15 G) was evaluated at three rates, two placements and three timings for ACP control in orange trees. RESULTS: Application of aldicarb at 5.6, 2.8 and 1.4 kg AI ha?1 in March 2006 reduced adults by 58–66%, 45–46% and 25–37% respectively compared with untreated controls in two separate trials. No difference was observed in placement (one versus two sides of the tree) or tree size (8 years old versus 12 years old). Application at 5.6 kg ha?1 in January 2007 reduced adults by 86% and shoot infestation by 77% in spring, and was generally better than the November and especially February applications. Even more striking results were evident on adults caged on treated plants for 25 days in March. Spiders and ladybeetles were equally abundant in treated and untreated trees. CONCLUSION: Aldicarb application at 5.6 kg ha?1 to the bed side of mature citrus trees 2–3 months before spring growth can suppress ACP through spring without a direct effect on principal psyllid natural enemies. Copyright © 2008 Society of Chemical Industry  相似文献   

18.
Residues of the herbicide dinoseb were determined gas chromatographically in lentils which had been treated at two locations in Saskatchewan with post-emergence applications of dinoseb at 1.4 and 1.7 kg ha?1. Herbicide residues, determined at selected times after application, were not detected at the limit of detection of the analytical method (0.05 mg kg?1) in either the seed and straw at maturity, or in the green foliage six to eight weeks after application. Recoveries of dinoseb were 76% from fortified green foliage at the 0.1 mg kg?1 level, and 64% from fortified seed at the 0.05 mg kg?1 level.  相似文献   

19.
Strawberries were sprayed with solutions of 200, 300 and 500 mg dimethoate litre?1 and analysed for dimethoate residues up to 21 days after the final spraying. The residues were found to be below the National Health and Medical Research Council limit of 2 mg kg?1, 1, 2 and 4 days after spraying. Consequently, the withholding period of 7 days could be reduced to 3 days to allow uninterrupted picking of the ripe strawberry crop.  相似文献   

20.
Residues of endosulfan insecticide (α- and β-isomers, and ‘endosulfan sulphate’) in fish and their predators were measured during and after operations to control tsetse fly in the Okavango Delta, Botswana. Six ultra-low-volume doses of endosulfan 35% e.c. (6–12 g a.i. ha?1) were applied from the air in a period of 12 weeks over 2500 km2. The concentration of residues found in living fish was up to 0.19 mg kg?1 wet wt in caudal muscle, and usually < 0.8 mg kg?1 wet wt in pooled viscera (maximum 2.8 mg kg?1). These values returned to near-normal within 3 months after cessation of spraying, but residues were still detectable after 12 months. By comparison, fish killed by spraying contained a maximum residue level (whole-body) of 1.5 mg kg?1 wet wt. The residue level in fish was approximately proportional to their fat content. Lean fish were more susceptible to poisoning than fat fish. The proportion of the ‘endosulfan sulphate’ metabolite in fish increased at least six times with respect to the parent isomers (α+β) during the period of spraying, but more advanced stages of metabolic breakdown were not monitored. Residue levels in fish predators (fish-eating birds and crocodiles) were similar to those in their prey, and the risk to them was consequently low.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号