bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photo‐dimers from the photolysis of 2‐dimethylamino‐5, 6‐dimethylpyrimidin‐4‐ol in aqueous solution
Authors: Sen Devdoot , Wells Clifford H. J. 
Published: November 2006

AbstractPhotolysis of 2‐dimethylamino‐5, 6‐dimethylpyrimidin‐4‐ol (I) in degassed aqueous solution yields two isomeric photo‐dimers which are formed by dimerisation across the 5, 6‐double bond of I. The yield of dimers is dependent upon the initial concentration of I and on the temperature; this can be explained in terms of a mechanism whereby pyrimidinol aggregates react to give dimers. The formation of aggregates can account for the fact that the quantum yield for the overall reaction of I was higher in degassed acetonitrile than in degassed aqueous solution, it can also account for four photo‐dimers being formed in the former solvent and only two in the latter solvent. The photo‐dimers revert to I when heated or on photolysis. That photodimers are not formed under natural conditions in the environment is considered to be partly because oxygen may react competitively with photo‐excited pyrimidinol species and so prevent dimerisation.
Studies on substituted aryloxyalkanols as potential fungicides
Authors: Giri Somari , Singh Yogendra , Srivastava Girish C. , Mekrani Shahid 
Published: November 2006

Abstract2‐(4‐Fluorophenoxy)ethanol and 2‐(4‐chloro‐m‐tolyloxy)ethanol, prepared by the reduction of appropriate esters with aluminium lithium hydride, have been found to be remarkably active against Aspergillus flavus, Helminthosporium oryzae, and four species of aquatic fungi that are responsible for fish mycoses. These chemicals were not lethal to fish even at the highest concentration used for fungicidal screening.
Influence of some 1,3,5‐triazine herbicides on peroxidase activity in corn seedlings
Authors: Tafuri Francesco , Scarponi Luciano , Perucci Piero , Giusquiani P. Lodovico 
Published: November 2006

AbstractThe effect of some 1,3,5‐triazine herbicides, on the rate of oxidative decarboxylation of tryptophan by peroxidase from corn seedlings, varied with the concentration. Atrazine was stimulatory in vivo at 10‐6M but not at 108 M or lower, whereas terbutryne was inhibitory at 10‐6M but not at 10‐8M or below. Prometryne inhibited enzyme activity at 10‐6M and stimulated it at 10‐10M and at 1012M, while simazine caused stimulation at 10‐6M and inhibition at 10−10M and 10−12M. Atraton reduced enzyme activity at 10−6M and 10−8M but had no effect at 10−10M and 10−12M. When peroxidase activity was assayed in acetone‐dried powders from seeds, harvested from fields that had received typical atrazine applications, the quantities of tryptophan consumed were significantly less than the quantity determined in the control powder. From the results obtained, by incorporating dealkylated and 2‐hydroxy metabolites of atrazine at 10−6M into the culture solutions, it seems possible that the inhibition observed may have been due to the presence of 4‐amino‐6‐ethylamino‐1, 3, 5‐triazin‐2‐ol and/or 4, 6‐diamino‐1, 3, 5‐triazin‐2‐ol residues in seeds from treated plots, even if, in previously reported experiments, analyses had not detected their presence.
The phytotoxicity of narrow distillation range petroleum spraying oils to valencia orange trees in South Australia. Part III: The influence of distillation temperature and spray timing on leaf and fruit drop
Authors: Furness Geoffrey O. 
Published: November 2006

AbstractPetroleum oil sprays are used as pesticides on citrus to control California red scale (Aonidiella aurantii Maskell), but may have phytotoxic effects on trees and fruit. As part of a programme to establish improved specifications for spray oils for South Australia, three oils with different 50 %‐distillation temperatures were applied to trees each month from October to May to observe their effects on leaf and fruit drop. The 50%‐distillation temperatures of the three oils were 211, 224 and 240°C at 10 mmHg (in order of increasing molecular weight). The oils caused significant leaf drop. The higher the 50%‐distillation temperature of the oil, the greater the leaf drop. Most leaf drop was caused when natural leaf drop was greatest. Oils applied from October to February caused severe leaf drop for periods of about 1–2 months, while oils applied from March to May caused severe leaf drop for up to 6 months or more. There was also a tendency for oils with a lower 50%‐distillation temperature to cause leaf drop sooner after spraying than oils with a higher 50%‐distillation temperature. Significant fruit drop was caused in only a few treatments, but the maximum fruit drop was less than 5% of the total fruit number and of little consequence when compared with the effects of oils on yield through reduced fruit set. Visually, a significant proportion of the total number of leaves present fell in many of the oil spray treatments, and the rate of disappearance of the oil film was directly related to the 50%‐distillation temperature of the oil, and to the spraying date.
Quantitative structure‐activity relationships of the inhibition of photosynthetic electron flow by substituted diphenyl ethers
Authors: Berg Gerard Van Den , Tipker Jacobus 
Published: November 2006

AbstractThe effect of 41 substituted diphenyl ethers (derivatives of nitrofen and chloroxuron) on photosynthesis in isolated spinach chloroplasts has been studied. All the chemicals were found to be inhibitors of non‐cyclic electron transport; the pI50 values varied from 3.17 to 7.16 (I50 is the molar concentration causing 50% inhibition; pI50= ‐log I50). Based on their structures, the compounds were divided into four groups; for most groups, a correlation between the inhibition of photosynthesis and physicochemical parameters was found. Lipophilicity proved to be the most important parameter; electronic effects did not play a role. Introduction of substituents into the nitrophenyl ring of nitrofen lowered activity considerably. Nitrofen and and chloroxuron analogues seemed to inhibit at different sites in the electron transport chain. A relationship between inhibition of photosynthesis and herbicidal activity was not clear.
Accumulation of endosulfan residues in fish and their predators after aerial spraying for the control of tsetse fly in Botswana
Authors: Matthiessen Peter , Fox Peter J. , Douthwaite Robert J. , Wood Alan B. 
Published: November 2006

AbstractResidues 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−1wet wt in caudal muscle, and usually < 0.8 mg kg−1wet 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−1wet 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.
Diurnal fluctuations in susceptibility to insecticides in several strains of the yellow fever mosquito (Aedes aegypti L.)
Authors: Bainbridge Carole A. , Margham Philip , Thomas Michael 
Published: November 2006

AbstractLarvae and adults of three strains of the yellow fever mosquito Aedes aegypti L. were tested to determine the presence or absence of a diurnal rhythm of susceptibility to the organochlorine insecticides dieldrin and DDT. Each strain showed different patterns of larval susceptibility to the toxicants. Larvae and adults of the same strains produced opposite time‐dependent responses to treatment. The significance of daily patterns of changing susceptibility in toxicological studies is discussed.
Studies of the disappearance of nine pesticides on celery and lettuce grown on muck soils in Ontario, 1977–1980
Authors: Braun Heinz E. , Ritcey Gwen M. , Ripley Brian D. , McEwen Freeman L. , Frank Richard 
Published: November 2006

AbstractNine experiments involving seven insecticides and two fungicides were conducted with celery and lettuce between 1977 and 1980 in order to provide data which would confirm or up‐date the current recommendations for registered compounds, and also to provide data on the disappearance rates of alternative non‐registered insecticides. Endosulfan, applied to celery at a rate of 0.8 kg ha−1, required 14 days to decline below the tolerance level of 1.0 mg kg−1; residues of methomyl on celery declined below the tolerance level of 2.0 mg kg−1 within the first 3 days. Parathion, when applied as an emulsifiable concentrate to celery, required greater than 21 days to decline to the tolerance level of 0.7 mg kg−1, compared with 10 days when applied as a wettable powder. Applications of parathion on celery, at repeated weekly intervals at a rate of 0.3 kg ha−1, produced significantly higher initial residues with five applications than when one or three applications were made; after 10 days from the terminal application, there were only slight differences in residue levels. Maneb and zineb residues declined below tolerance levels within 3–7 days following application. Alternative insecticides investigated for use on celery and lettuce included acephate, cypermethrin, fenvalerate and permethrin. Celery, treated with acephate at a rate of 0.75 kg ha−1, required more than 13 days for residues to decline below a negligible level (0.1 mg kg−1); the disappearance of acephate in lettuce appeared to be somewhat faster, requiring from 3 to 14 days to decline to the 0.1 mg kg−1 level. Cypermethrin, fenvalerate and permethrin, all applied at the rate of 0.08 kg ha−1, disappeared rapidly on both celery and lettuce, and the residues fell below 0.1 mg kg−1 within 8–14 days on celery, and within 3–7 days on lettuce.
A study of the stability of conjugates of N‐benzoyl‐N‐(3‐chloro‐4‐fluorophenyl)‐DL‐ alanine during extraction from Avena sativa
Authors: Pillmoor John B. , Roberts Terry R. , Gaunt John K. 
Published: November 2006

AbstractExtensive metabolism occurred within 24 h of treatment during studies of N‐benzoyl N‐(3‐chloro‐4‐fluorophenyl)‐DL‐alanine (I) in oats. However, marked differences were observed in the apparent pattern of metabolism when different methods of extraction were used. Two major groups of metabolites were found (based on chromatographic behaviour), the first containing mainly the glucose ester of I, and the second containing other sugar conjugates of I. These groups of metabolites and the residual I could be extracted from plants with either aqueous acetone or boiling ethanol to give the same quantitative distribution of metabolites. However, if 80% ethanol was used as extraction solvent, and sodium hydrogen carbonate was used as a leaf wash prior to extraction, dramatic decreases were observed in the concentration of conjugates formed, and large quantities of the ethyl ester of I were also formed. It is concluded that the common experimental practice of using sodium hydrogen carbonate or other alkaline reagents for washing residual herbicides from treated leaves should be avoided, particularly in studies with acidic herbicides.
Removal of the phytotoxicity of uracil herbicides in water by photodecomposition
Authors: Saltzman Sarina , Brates Nelly , Horowitz Menashe , Gevelberg Assia 
Published: November 2006

AbstractThe efficiency of a photo‐oxidation procedure for the detoxication of water containing herbicides of the uracil group was tested by bioassay. Treated herbicide solutions were checked for their inhibiting effect on germination and photosynthesis in sorghum (Sorghum bicolor). The treated solutions, and the main photodegradation products of bromacil and terbacil did not inhibit significantly either germination or seedling development at concentrations of up to 200 and 10 mg litre−1, respectively. Preliminary tests with industrial waste effluents containing added uracil compounds showed that these compounds were rendered non‐phytotoxic by the photo‐oxidation procedure.
Photolytic demethylation of monuron and demethylmonuron in aqueous solution
Authors: Tanaka Fred S. , Wien Ronald G. , Mansager Eugene R. 
Published: November 2006

AbstractPhotochemical demethylation of monuron [3‐(4‐chlorophenyl)‐1, 1‐dimethylurea] and of demethylmonuron [ 1‐(4‐chlorophenyl)‐3‐methylurea] in aqueous solution was investigated. The photoproducts identified in this study were formaldehyde, formic acid and carbon dioxide. These products indicate that demethylation occurs either by oxidation of a methyl group to hydroxymethyl which is readily cleaved to yield formaldehyde, or by further oxidation to an N‐formyl group, which is slowly hydrolysed under weakly acidic conditions to yield formic acid. Samples equilibrated either with air or oxygen (> 99 % purity) gave essentially the same yield of oxidation products. Experimental evidence indicated that extensive photodegradation of formaldehyde was occurring during photolysis, causing low recoveries of formaldehyde. Consequently, with [2H3‐methyl]demethylmonuron and deuterated water, only steady state concentrations of formaldehyde could be measured in an isotopic study.
Mode of action of the systemic fungicides furalaxyl, metalaxyl and ofurace
Authors: Fisher David J. , Hayes Ann L. 
Published: November 2006

AbstractThe systemic fungicides furalaxyl, metalaxyl and ofurace,Ofurace is the proposed BSI and ISO common name for α‐(2‐chloro‐N‐2,6‐xylylacetamido)‐γ‐butyrolactone.
used to control diseases caused by phycomycetes, were extremely active in vitro against Pythium ultimum, Phytophthora nicotianae and Phytophthora palmivora. Sporangia production was reduced more than mycelial growth but germination of sporangia and zoospores was relatively unaffected. Less than 1% of the metalaxyl or furalaxyl, present in media at the ED50 for hyphal growth, was firmly absorbed by Phyt. palmivora mycelium; uptake was against a concentration gradient and was characterised by a rapid accumulation followed by a more gradual release. Respiration and wall synthesis were not inhibited, whilst membrane permeability was unaffected. Lipid patterns were altered but these changes were probably of secondary importance. The fungicides inhibited protein and nucleic acid synthesis; RNA production was particularly affected. There was some evidence of a reduction in nuclear division. The primary effect of furalaxyl and metalaxyl probably involves impaired biosynthesis of RNA so that mitosis is inhibited; ofurace may act in the same way.
The toxicity of diflubenzuron to Oxya japonica (Willemse) and its effect on moulting
Authors: Lim Suat‐Jien , Lee Soo‐Seong 
Published: November 2006

AbstractA laboratory evaluation of the acute toxicity of diflubenzuron against the final stage of Oxya japonica nymphs showed that it was more effective in preventing the development of the nymphs into the adults when applied topically, than when injected. Histological studies revealed that treated nymphs that subsequently died, before or during ecdysis, suffered from severe endocuticular lesions. Comparable abnormalities and disruption of endocuticular deposition and growth were also seen in nymphs that were treated topically with diflubenzuron at 50 or 200 μg a.i. per insect, although these nymphs appeared normal externally.
Distribution and breakdown of DDT in orchard soil
Authors: Cooke Barry K. , Stringer Austin 
Published: November 2006

AbstractAmounts of DDT and its breakdown products were determined in soil in an apple orchard in Herefordshire. Samples were taken for a number of years (1972–79) after use of the insecticide in the orchard had ceased in 1969. The results were compared with those obtained in an investigation of the same orchard in 1968. From 1968 to 1979, soil residues of pp′‐DDT, p′‐‐DDT and pp′‐‐TDE decreased gradually whereas those of pp′‐‐DDE increased, and there were linear relationships between log (concentration) and time. The calculated time for 50% decrease in concentration (Dt50) was 11.7 years for pp′‐‐DDT, 3.3 years for pp′‐‐TDE and 7.1 years for op′‐‐DDT; the time for doubling the concentration for pp′‐‐DDE was 9.1 years. Regression analysis on the two major components (pp′‐‐DDT+pp′‐‐DDE) indicated that the total amount (2.7 mg kg−1) was not decreasing with time. It was concluded that during a post‐spray era, the breakdown of pp′‐‐DDT to pp′‐‐DDE was a significant feature of the persistence of DDT, and that, in contrast to the findings of other workers who sampled when DDT was being used, there were no losses by volatilisation. There was an exponential decrease in the amount of DDT residues with increasing soil depth and approximately 90% was found in the top 10 cm of the undisturbed soil profile.
A laboratory evaluation of the effectiveness of diflubenzuron against Dermestes maculatus De Geer and other storage insect pests
Authors: Webley David J. , Airey William A. 
Published: November 2006

AbstractThe 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.
Changes induced by phorate in the carbohydrate metabolism of the snail Lymnaea acuminata
Authors: Mahendru Vijay K. , Agarwal Ram A. 
Published: November 2006

AbstractCarbohydrate metabolism was studied in the hepatopancreas, mantle, intestine and foot of the snail Lymnaea acuminata, exposed to 40% and 80% of the LC50 dose of phorate (12 and 24 mg litre−1, respectively) for 24 and 48 h. Following treatment with the pesticide, the rate of oxygen consumption and the glycogen contents were reduced, while the levels of lactic acid and reducing sugars were enhanced. Withdrawal of the pesticide for 7 days after exposure of the snails to 12 mg of phorate litre−1 for 48 h did not reverse these changes.
Extraction and identification of a new degradation product of atrazine in the soil
Authors: Tafuri Francesco , Patumi Maurizio , Marucchini Cesare , Businelli Mario 
Published: November 2006

AbstractGas‐chromatographic analyses of extracts of soil samples from plots, treated with a 50% atrazine wettable powder at dose rates of 2 and 4 kg a.i. ha−1, showed the presence of a new atrazine degradation product. This product was isolated, concentrated and purified by column chromatography and high‐performance liquid chromatography. The chromatographic properties of this material were identical with those of a product isolated from a 0.02% methanolic solution of 2‐amino‐4‐chloro‐6‐isopropyl‐amino‐1,3,5‐triazine that had been stored under laboratory conditions. A combined gas‐liquid chromatographic/mass spectrometric assay identified the new product in soil as 2‐isopropylamino‐4‐methoxy‐6‐methylamino‐1,3,5‐triazine.
Diffusion and uptake of chemical vapour volatilising from a sprayed target area
Authors: Thompson Nigel 
Published: November 2006

AbstractEstimates are made of the concentrations of vapour near the surface at different distances down‐wind from sprayed areas of various sizes from which vapour is volatilising at a known rate. Deposition velocities are also calculated for vapour transfer to an underlying crop, the leaves of which either act as a perfect sink, or provide stomatal pathways through which vapour may be absorbed. Typical values of the deposition velocities calculated on these bases are found to be around 5 × 10−3m s−1 in the case of vapours with molecular weights around 300 (applicable to many spray chemicals). These results are combined and applied to cases in which the vapour source is a few hundred metres long in the direction of the wind, and very broad. It is found that the calculated rate of uptake of vapour by the down‐wind underlying surface may exceed 1% of the rate of production of vapour by the source (in each case, per unit area), even at distances more than 500 m from the source area. The reasons why field values of uptake may fall short of these theoretical estimates are briefly discussed.
Herbicide antidotes—A review
Authors: Parker Christopher 
Published: November 2006

AbstractThe history of herbicide antidotes is reviewed, beginning with the exploration of compounds to protect wheat (Triticum aestivum L.) against barban in the early 1960s, and the later introduction of naphthalic anhydride (NA, naphthalene‐1, 8‐dicarboxy‐licanhydride) as a seed dressing for protecting maize (Zea mays L.) against EPTC. This compound was largely replaced by Stauffer's R‐25788 (N, N‐diallyl‐2, 2‐dichloroacetamide) which has continued to be widely used in conjunction with EPTC and butylate in maize. This compound is highly specific to maize and can thus be applied in admixture with the herbicide, but has not proved of practical value on other crop species. NA on the other hand is less specific and is of potential value on sorghum [Sorghum bicolor (L.) Moench] and rice (Oryza sativa L.); experimental work continues on these crops. The only other antidote to be marketed so far is cyometrinil as a seed dressing for protecting sorghum against metolachlor and related herbicides. Other compounds are under development. Mode of action and structure‐activity relations are discussed, as well as the current and future potential for antidotes in respect of the control of weed species in closely related crops, the increased options for herbicide use in minor crops and the possibility of reduced costs for broad spectrum weed control in major crops.
Toxicology and metabolism of some synthetic pyrethroids in larvae of susceptible and resistant strains of the cattle tick boophilus microplus (Can.)
Authors: Schnitzerling Herbert J. , Nolan James , Hughes Suzanne 
Published: November 2006

AbstractLarvae of the Malchi and DDT‐R pyrethroid‐resistant strains of ticks, compared with larvae of the Yeerongpilly (susceptible) strain, exhibited knock‐down resistance equally to (1 RS)‐cis‐ and (1 RS)‐trans‐permethrin but little resistance to either (1 RS)‐cis‐ or (1 RS)‐trans‐cypermethrin. Kill resistance was higher in Malchi than in DDT‐R ticks and more pronounced against the permethrin isomers. The cis‐isomers were more potent overall than the trans‐isomers. Cypermethrin isomers penetrated more slowly than permethrin isomers, especially into Malchi larvae. Metabolic detoxication, mainly esteratic, was fastest in Malchi larvae, trans‐isomers consistently being attacked faster than cis‐isomers. The greatei resistance of Malchi ticks is therefore probably due to a combination of these two differences. Dual mechanisms of the toxic action of pyrethroids are discussed.