bluuebunny/crossref_metadata_2025_split huggingface dataset:
An ultrastructural study of the effect of metalaxyl on Phytophthora capsici infected stems of Capsicum annuum
Authors: Hwang Byung Kook , Ebrahim‐Nesbat Firous , Ibenthal Wolf‐Dieter , Heitefuss Rudolf 
Published: November 2006

AbstractStems of pepper seedlings were inoculated with zoospores of Phytophthora capsici 18 h after a soil‐drench with metalaxyl solution (5 μg ml−1) or water. Infected stem tissues were examined by electron microscopy 24 h after inoculation. Compared with untreated controls, in which the fungal cells were generally normal in shape and ultrastructure, the most conspicuous effects of metalaxyl treatment on the fungal ultrastructure in the stem tissue were an abnormal shrinking of the fungal cell, a separation of the plasma membrane from the hyphal wall, a peculiar invagination and breakdown of the plasma membrane, the presence of vesicles in the invaginated spaces and within the damaged fungal cells, and an indistinct structure of cell organelles. In metalaxyl‐treated stems, an electron‐dense material was apposed in those sites of the host cell wall in most intimate contact with the fungal cell wall, indicating that the deposition of these substances from the host cell walls may function as a plant defence reaction to the fungus, whereas in untreated controls, the dark‐stained host cytoplasm did not aggregate around the sites of fungal contact. The haustorium was encased by the extra‐haustorial matrix in treated stems. These results suggest that metalaxyl treatment not only changes the fine structure of P. capsici, but may also induce the plant defence reaction.
Rationalisation of the mass spectrometric and gas chromatographic behaviour of organophosphorus pesticides: Part 1–substituted phenyl phosphorothioates
Authors: Wilkins John P. G. 
Published: November 2006

AbstractThe mass spectrometric and gas chromatographic behaviour of a series of O,O‐dialkyl O‐(substituted phenyl) phosphorothioates, and some related compounds is reported. Several of these compounds are widely used as pesticides. Appraisal of these data has permitted an increased understanding of the influence of phenyl substituents on the appearance of the mass spectra of these compounds. In particular, the nature and extent of mass spectrometric ortho effects, which are associated with weak molecular ion intensity, and/or the generation of rearrangement ions are reported. Examples in which an understanding of these effects has been helpful in the identification of related compounds, such as technical impurities and degradation products, are given. Published mass spectrometric data for some of these compounds are critically appraised.
Herbicides inhibiting branched‐chain amino acid biosynthesis
Authors: Moberg William K. , Cross Barrington 
Published: November 2006

AbstractHerbicides inhibiting branched‐chain amino acid biosynthesis represent a signal advance in crop protection chemistry, with implications for both practical weed control and basic agricultural science. In practical terms, at least 20 different active ingredients are currently marketed or are in development, and more may be expected. They offer selectivity in virtually every major crop, unprecedented low use rates, and inherently selective toxicity to plants. In scientific terms, the research behind these compounds shows modern agricultural chemistry at its best. Synthesis has been integrated with other disciplines to understand and rapidly optimize properties. In the process, basic knowledge has been gained in chemistry, biochemistry, and strategies for finding new agrochemicals.This issue provides the first unified, interdisciplinary overview of the three major classes of inhibitors–sulfonylureas, imidazolinones, and triazolopyrimidines. The following introductory note explores some implications of this research.
Acetolactate synthase, mechanism of action and its herbicide binding site
Authors: Schloss John V. 
Published: November 2006

AbstractSeveral new structurally diverse classes of herbicide, including the sulfonylurea herbicides, act by inhibiting acetolactate synthase, the first common enzyme of branched‐chain amino acid biosynthesis. The interaction of acetolactate synthase isozyme II (ALSII) from Salmonella typhimurium with sulfometuron methyl (SM), a sulfonylurea herbicide, has been used as a paradigm in elucidating the mode of action of these herbicides at the molecular level. A number of different studies have collectively suggested that SM binds to ALSII near thiamine pyrophosphate and flavin adenine dinucleotide (FAD), with its binding site overlapping the second pyruvate (or ketobutyrate) substrate site. Most of SM, however, must be accommodated on ALSII at a site that is not equivalent to substrate or co‐factor binding sites. The identity of this herbicide‐specific site has recently been suggested by the discovery that poxB, the gene for pyruvate oxidase, shares substantial sequence homology with ilvB, ilvG and ilvI, the genes for the large subunits of ALSI, ALSII, and ALSIII, respectively. Unlike ALSII, pyruvate oxidase uses its FAD for normal redox chemistry, and binds one additional co‐factor in vivo, ubiquinone‐40. The latter co‐factor binds to pyruvate oxidase in a spatially and kinetically equivalent way to SM with ALSII, suggesting that the herbicide binding site of ALSII has a common evolutionary heritage with the ubiquinone site of pyruvate oxidase.
Imidazolinone inhibition of acetohydroxyacid synthase in vitro and in vivo
Authors: Stidham Mark A. , Shaner Dale L. 
Published: November 2006

AbstractImidazolinone herbicides inhibit the first enzyme of branched‐chain amino acid biosynthesis, acetohydroxyacid synthase. The inhibition of the enzyme in vitro by these herbicides increases with incubation time, but is not irreversible, as deduced by reaction progress curves. In contrast to this result is the apparent irreversible inhibition of the enzyme by these imidazolinones that occurs when the herbicide is applied to intact corn plants. Plants treated with imidazolinone herbicide and then extracted showed dramatically reduced enzyme activity. This effect on extractable enzyme level occurred with several different imidazolinone herbicides in either foliar or soil application. The decrease in extractable enzyme activity could be observed within four hours after treatment. Herbicides other than imidazolinones did not reduce the extractable enzyme level. These findings suggest that the enzyme‐ imidazolinone interaction in vivo may be different from the interaction observed in vitro.
Fungicidal activity of a series of 1‐substituted‐1‐aryl‐2‐triazol‐1‐yl‐ethanols
Authors: Chollet Jean‐François , Bonnemain Jean‐Louis , Miginiac Léone , Rohr Otto 
Published: November 2006

AbstractTwenty‐four I‐substituted‐I‐aryl‐2‐triazol‐I‐yl‐ethanols were prepared by the reaction between acetylenic, propargylic or allylic organometallics and aryl triazolylmethyl ketones. These were tested for antifungal activity against ten phytopathogenic fungi of different taxonomic classes. EC80 values were determined for the seven most active compounds and for two commercial compounds, hexaconazole and flusilazole. In these tests, the fungicidal activity of the new compounds was generally lower than that of the two reference triazoles except for two products which were more active than hexaconazole and flusilazole against powdery mildew on barley.
Trends in the formulation of pesticides—an overview
Authors: Seaman David 
Published: November 2006

AbstractThe customer increasingly requires safer and more convenient pesticide formulations. Emulsifiable concentrates and wettable powders are nowadays viewed less favourably by farmers and registration authorities. Suspension concentrates are now common and water‐dispersible granules and emulsions in water are receiving increasing attention. Capsule suspensions offer both safer and more effective performance in favourable cases. For convenience the farmer requires multi‐component products, either as mixtures of active ingredients, which might be as suspoemulsions, or with built‐in enhancing surfactants and oils. Seed treatments are now required as aqueous suspensions and the seed is increasingly of interest as an eficient carrier for pesticides. Research into biological control agents sets the difficult challenge of formulating these products as viable organisms. Three examples of developments are described. These are the applications of polymeric surfactants for suspension concentrates and suspoemulsions, studies of enhancement of pesticide uptake with surfactants and developments in microencapsulation.
The structure/physical property relationships of a model water‐dispersible granule
Authors: Bell Gordon A. 
Published: November 2006

AbstractThe particles constituting a water‐dispersible granule are arranged in a structure which determines the physical properties of that formulation. To examine the importance of such structures, four examples were prepared which were significantly different in terms of bonding and porosity. Examination by electron microscopy and mercury porosimetry indicated that granule strength and dispersion properties were determined by a combination of structure and bonding. A compact granule with weak bonds proved to be a suitable structure for fast dispersion and high solid strength.
A rapid method using Ricinus communisfor the estimation of phloem translocation of xenobiotics
Authors: Bromilow Richard H. , Chamberlain Keith , Patil Shantagouda G. 
Published: November 2006

AbstractA simple and relatively rapid test has been developed that enables the phloem mobility of xenobiotics to be assessed. Compounds are applied by injection of an aqueous solution into the petioles of plants of castor bean (Ricinus communis var. Gibsonii), and phloem sap is collected from two incisions made in the stem below the treated leaves over the period of 2 to 4 h after application. Amounts of compounds in the sap are measured by liquid scintillation counting following thin‐layer chromatography for radio‐labelled samples or by high‐pressure liquid chromatography for non‐radio‐labelled compounds. A semi‐quantitative estimate of mobility in phloem can be obtained from these tests, including an estimate of the potential for long‐distance transport via phloem. Mobilities in phloem measured for 28 compounds, mostly weak acids, are placed within a general framework for understanding the phloem transport of compounds in terms of their physico‐chemical properties. This approach can be used to predict and interpret the behaviour of new compounds from a knowledge of their polarity and acid strength.
Simultaneous determination of clofentezine, fenoxycarb and hexythiazox by HPLC on apples, pears and their pulps
Authors: Bicchi Carlo , D'Amato Angela , Tonutti Ivano , Cantamessa Liliana 
Published: November 2006

AbstractThe 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.
The fate of chlorpyrifos‐methyl in stored wheat: A comparison of a laboratory‐scale experiment with a pilot‐scale treatment
Authors: Matthews Wendy A. 
Published: November 2006

AbstractAn experiment was carried out in which a pilot‐scale treatment of a bulk of grain with chlorpyrifos‐methyl was compared with a laboratory treatment of 1 kilogram of grain with 14C‐radio‐labelled chlorpyrifos‐methyl. The conditions under which the grain was maintained in the laboratory resembled those of the pilot‐scale treatment as closely as possible, with sampling and analysis being carried out at the same time and in a similar manner in both. The results from the two experiments were in general agreement with approximately 60% of the chlorpyrifos‐methyl remaining intact at the end. A satisfactory level of insect control was achieved in the pilot‐scale treatment although it was not possible to assess efficacy in the radiochemical experiment. The use of the radio‐label enabled more information about the fate of the degraded insecticide to be obtained from the laboratory experiment. The majority of this radioactivity comprised a fraction which remained within the grain tissue after solvent extraction. The level of activity in the grain tissues gradually increased with time but its nature is as yet unknown.The good agreement obtained between the residue profile and the breakdown patterns in both experiments would suggest that such a laboratory‐scale experiment can be a satisfactory model for the situation obtaining in a larger‐scale treatment.
Plant‐growth‐regulating phosphono peptides
Authors: Wieczorek Piotr , Lejczak Barbara , Kaczanowska Malgorzata , Kafarski Pawel 
Published: November 2006

AbstractPhosphono peptides exhibited plant‐growth‐regulating activity when tested on Lepidium sativum and Cucumis sativus. The studies have provided evidence that the mechanism of action of these compounds may involve the uptake of the phosphono peptides into the plant, intracellular hydrolysis of the peptide bond and release of the P‐terminal aminoalkylphosphonic acid. This acid or its metabolite is then probably responsible for the observed physiological effect.
The kinetics of insecticide action. Part IV: the in‐vivo distribution of pyrethroid insecticides during insect poisoning
Authors: Greenwood Richard , Ford Martyn G. , Peace Edwin A. , Salt David W. 
Published: November 2006

AbstractThe distribution of pyrethroids in insects has been studied using a combination of mathematical modelling and experimental observation. This approach has resulted in the formulation of a physiological model of the pharmaco‐kinetics of cypermethrin applied topically to larvae of Spodoptera littoralis. Development of this model from simpler two‐ and three‐compartment models is described. Simple models, whilst capable of complex behaviour, consider only the average rates and magnitudes of pharmaco‐kinetic processes over whole animals, and cannot account for differences in concentration of insecticide between individual tissues. This can be achieved by using physiological models, but these require more experimental information for their validation. Moreover, unless simplifying assumptions are made, analytical solutions are not feasible for the large number of equations necessary to define such models.The modelling studies prompted an investigation of (1) in‐vivo binding of insecticide to insect tissues, (2) the sizes of body compartments, and (3) the factors which affect the distribution of toxicant between these compartments. Binding has a marked effect on pharmacokinetic profiles and may result in oscillatory behaviour. During poisoning, the total bound cypermethrin increases proportionally to the cube root of the elapsed time. This results in a rapid rate of increase over early elapsed times (< 3h) which slows to approach a more linear form thereafter. Average sizes for the body compartments of larvae of Spodoptera littoralis Boisd, and the steady‐state distribution of cypermethrin in these compartments are described. Although the haemolymph, which acts as the main distributive phase during poisoning, forms the largest compartment by volume, it has a low affinity for cypermethrin and distribution reaches steady state within 5 min after topical application. The nerve cord (the target tissue), which is the smallest compartment, has the highest steady‐state concentration of cypermethrin. The distribution of cypermethrin in larval tissues is related to the ratios of tissue dry matter to water content.
The determination of residues of 2,4‐D in post‐emergence‐treated triticale
Authors: Cessna Allan J. 
Published: November 2006

AbstractA 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.
Off‐target deposits and buffer zones required around water for aerial glyphosate applications
Authors: Payne Nicholas J. , Feng Joseph C. , Reynolds Philip E. 
Published: November 2006

AbstractOff‐target deposit has been quantified from various silvicultural glyphosate application methods and an estimate made of the buffer‐zone widths required around water to protect fish and their invertebrate food species from possible toxicological effects. To overcome the difficulty of estimating different buffer widths to meet the various use conditions encountered, a realistic worst‐case scenario was chosen for small‐drop drift and data were collected accordingly. Three glyphosate application methods were tested, employing a helicopter equipped with a ‘Microfoil’ boom, a ‘Thru Valve Boom’ and D8‐46 hydraulic nozzles respectively. Airborne glyphosate and off‐target glyphosate deposits on ground sheets and foliar surfaces were measured at downwind distances between 50 and 200 m from multiple overlaid crosswind swaths. Over this distance airborne glyphosate decreased by factors of 3‐130, ground deposits by factors of 4‐2200, and foliar deposits by factors of 5‐100. In general, airborne glyphosate and off‐target deposit was highest from the D8‐46 application, and lowest from the ‘Microfoil’ boom application. Using these measurements, mathematical equations were formulated to predict glyphosate deposits on water surfaces downwind of multiple swath applications, and calculations made for 100‐ha applications. Large‐drop drift was also calculated using a ballistic model. An estimate was then made of buffer widths required around water bodies to prevent toxicological effects from small‐ and large‐drop drift, using reported glyphosate toxicities to salmon, rainbow trout and various aquatic invertebrates. A buffer width of 25 m around water bodies limits mortality in populations of salmon, rainbow trout and aquatic invertebrates to less than 10% for the application methods employing the ‘Microfoil’ and ‘Thru Valve’ Boom. For the third application method a 30‐m buffer width is suggested.
Catalytic hydrolysis of diclofop‐methyl on Ca‐, Na‐ and K‐montmorillonites
Authors: Pusino Alba , Gessa Carlo 
Published: November 2006

AbstractThe decomposition of the herbicide diclofop‐methyl (methyl (RS)‐2‐(4‐(2,4‐dichlorophenoxy)phenoxy)propionate), on homoionic Ca‐, Na‐ and K‐montmorillonite in hydroalcoholic suspension was investigated. The results show that the solvolysis of the pesticide affords two products: diclofop (RS)‐2‐(4‐(2,4‐dichlorophenoxy)phenoxy)propionic acid) and diclofop‐ethyl (ethyl (RS)‐2‐(4‐(22,4‐dichlorophenoxy)phenoxy)propionate). The former is always the main product of hydrolysis on the Ca‐, Na‐ and K‐clays, whereas the latter, arising from a transesterification reaction, is favoured only by the presence of Ca‐and Na‐clays. The solvolysis reaction follows the adsorption of the herbicide on the clay, as evidenced by the shift of the IR stretching value of the ester group of the molecule, depending on the polarising power of the saturating ions.
Field movement and persistence of fenamiphos in drip‐irrigated pineapple soils
Authors: Schneider Randi C. , Green Richard E. , Apt Walter J. , Bartholomew Duane P. , Caswell Edward P. 
Published: November 2006

AbstractThe persistence and mobility of fenamiphos and its toxic oxidation products in soil with pineapple cropping were studied in three field experiments on the islands of Oahu and Lanai, and by sampling three commercial fields on Oahu. Fenamiphos was applied by drip irrigation after planting, following pre‐plant application of 1,3‐dichloropropene (1,3‐D) in most treatments. The Oahu experiments, conducted on highly weathered Oxisol and Ultisol soils, evaluated the impact of restricted irrigation to reduce leaching and also the effect of 1,3‐D on fenamiphos behavior. Total toxic residue (TTR) concentrations of 1000 ug kg−1 or greater were maintained in the root‐zone with fenamiphos applications of 3.4 kg ha−1 tri‐monthly on the Oxisol (Kunia site) and bi‐monthly on the Ultisol (Whitmore site). The relatively high applications, along with weekly irrigations and unseasonably high rainfall, resulted in leaching of fenamiphos TTR out of the root‐zone with concentrations between 10 and 100 ug kg−1 at 3 m depth. Reduced leaching with restricted irrigation was evident in the early months of both Oahu experiments. The potential to minimize leaching of fenamiphos by reduced application rates and limited irrigation during rainy periods was evident from nematicide concentration profiles measured on three commercial pineapple fields on Oahu; little fenamiphos TTR was detectable below 1 m.
Interaction of formamidine pesticides with insect neural octopamine receptors: Effects on radioligand binding and cyclic AMP production
Authors: Orr Gregory L. , Orr Nailah , Cornfield Linda , Gole John W. D. , Downer Roger G. H. 
Published: November 2006

AbstractThe formamidines chlordimeform, demethylchlordimeform (DCDM), amitraz and BTS‐2727l were tested for their respective abilities to inhibit [3H]mianserin binding in membrane preparations of cockroach brain and, in the same tissue, to stimulate octopamine‐sensitive receptors coupled to adenylate cyclase. Analysis of [3H]mianserin binding indicated negative cooperativity between two binding sites with respective Kd and Bmax values of 3.82 mM and 0.886 pmol (mg protein)−1 for a high‐affinity site and 218 nM and 13.56pmol (mg protein)−1 for a low‐affinity site. DCDM, BTS‐27271 and amitraz inhibit [3H]mianserin binding with IC50 values similar to those obtained with octopamine and the μ‐adrenergic antagonist, phentolamine, whereas chlordimeform is a poor competitor for the binding sites. Similarly DCDM, BTS‐27271 and amitraz elevate cyclic AMP production in brain membrane preparations in a dose‐dependent manner with Ka values of 0.32 uM, 1.5 uM and 3.4 uM respectively, whereas chlordimeform was again without effect. The formamidine‐mediated responses were fully additive with the evaluation of cyclic AMP obtained using the maximal concentration of dopamine but not with octopamine‐mediated increases; thus the formamidine effects appear to be expressed through partial agonism of octopamine receptors that are coupled to adenylate cyclase.