bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulatory pressures on pesticide formulations
Authors: Thomas Barry
Published: November 2006

A greater public, political and regulatory awareness of chemicals in general, and in particular of their environmental behaviour, has led to increased attention being given to the so called ‘inert’ ingredients of pesticide formulations. Specific controls of these ‘inerts’ have been developed and introduced in the USA whilst in Europe the approach at national and Community level has been more broad‐based. These legislative controls and their associated influence on the labelling and data requirements for pesticide formulations are discussed. The positive move towards ‘safer’ formulations is to be welcomed and will hopefully not lose momentum in the light of increasing regulatory pressure on the individual constituents.
Influence of solid/liquid ratio on the experimental frror of sorption coefficients in pesticide/soil systems
Authors: Boesten Jos J. T. I.
Published: November 2006

The influence of the solid/liquid ratio on the experimental error in the sorption coefficient in pesticide/soil systems was assessed by theoretical analysis. It was assumed that the sorption coefficient is derived from the measured decrease in concentration in the liquid phase of a soil suspension. A first analysis based on systematic errors in the concentration in the liquid phase showed that the relative error in the sorption coefficient is controlled by the product of the solid/liquid ratio and the sorption coefficient (a dimensionless quantity). If this quantity tends to zero, the relative error tends to infinity. A second analysis, based on random errors in the concentration in the liquid phase, gave a similar result. To minimize experimental errors the solid/liquid ratio should be taken as large as possible unless the equilibrium concentration becomes too low to be measured accurately.
The use of pharmacokinetic models in the development and evaluation of site‐specific drug delivery systems
Authors: Aarons Leon , Boddy Alan
Published: November 2006

The influence of the pharmacokinetics of drug‐carrier conjugates and free drug and of the pharmacodynamics of therapeutic and toxic responses on the potential for successful targeting is discussed. A simple physiologically based compartmental model is used to explore the potential of drug‐targeted systems versus conventional administration. The major kinetic factors affecting the therapeutic advantage of targeted systems are the blood flow to the target site, the systemic clearance of free drug and the selectivity of release of drug from its carrier. A model independent analysis based on linear systems theory using a recirculating model of drug disposition is also described.
Effect of seed treatment in preventing transmission of dwarf bunt of winter wheat to new areas
Authors: Mathre Don E. , Johnston Robert H. , Grey William E.
Published: November 2006

The effectiveness of various fungicide formulations containing carboxin and thiabendazole in eradicating teliospores of Tilletia controversa (dwarf bunt) from winter wheat seed was evaluated in the laboratory and the field. In the laboratory tests, the viability of teliospores washed from treated infested seed was greatly reduced as compared to the viability of teliospores washed from untreated infested seed, suggesting that carboxin and thiabendazole were primarily fungicidal. Field tests in two different years were established to determine if teliospores from treated infested seed could infect nearby untreated noninfested seed. Formulations containing carboxin were highly effective in reducing infection of healthy seed. No dwarf bunt infected plants developed in either year from seed treated with ‘Vitaflo 250’. Furthermore, seedborne common bunt caused by Tilletia foetida was nearly eradicated by carboxin‐containing formulations in one field test. Carboxin treatment of winter wheat seed infested with dwarf bunt teliospores will greatly reduce the danger of introducing this pathogen into new areas.
Invertebrate pharmacological assay of novel, potent glutamate receptor antagonists: Acylated spermines
Authors: Blagbrough Ian S. , Bruce Mary , Bycroft Barrie W. , Mather Alan J. , Usherwood Peter N. R.
Published: November 2006

Synthetic analogues of arthropod polyamine‐containing toxins have been investigated for antagonism of the quisqualate‐sensitive L‐glutamate receptor (quis‐GluR) of locust muscle. Block of the cation‐selective channel gated by quis‐GluR was demonstrated for N‐(4‐hydroxyphenylpropanoyl)‐and N‐(4‐hydroxyphenylacetyl)‐spermine at significantly lower concentrations than that for spermine.
Volatile analogues of penconazole and their activity against the take‐all fungus, Gaeumannomyces graminis var. tritici
Authors: Chamberlain Keith , Bateman Geoffrey L. , Nicholls Peter H.
Published: November 2006

Eight new sterol biosynthesis‐inhibiting fungicides, structurally related to penconazole and having vapour pressures up to 118 mPa, were synthesised. Their toxicities to the cereal take‐all fungus, Gaeumannomyces graminis var. tritici, on agar were measured; intrinsic activities were measured after incorporating the compounds into the agar and vapour activities were measured after their evaporation from glass and from moist soil. Vapour activity following evaporation from soil was shown to be a function of both the intrinsic activity of the compound and its partition coefficient between the air and moist soil (Kas). The latter is itself a function of vapour pressure, 1‐octanol/water partition coefficient (Kow) and the soil type. The compound most active as vapour from soil in the in‐vitro test, 1‐(pyridin‐3‐yl)‐2‐(4‐flurorophenyl)pentane, was ineffective against take‐all in wheat in a pot test in which the inoculated soil was treated unevenly, providing further evidence that the redistribution of fungicides in moist soil occurs predominantly via the water phase rather than the vapour phase.
Transformation rate of 1,3‐dichloropropene and 3‐chloroallyl alcohol in topsoil and subsoil material of flower‐bulb fields
Authors: Leistra Minze , Groen Ariette E. , Crum Steven J. H. , van der Pas Leo J. T.
Published: November 2006

The extent of the risk of (Z)‐ and (E)‐1,3‐dichloropropene and their transformation products (Z)‐ and (E)‐3‐chloroallyl alcohol causing a hazard to the quality of groundwater pumped up for public water supply from below flower‐bulb fields has been evaluated. The 1,3‐dichloropropenes were incubated at 10°C in water‐saturated subsoil material from three such fields. A first stage with gradual transformation was followed by a second stage with comparatively rapid transformation and after three months negligible amounts remained. The 3‐chloroallyl alcohols were incubated at 15°C in soils from the root zone of the same fields. Complete transformation had occurred in about a week or even less. The 3‐chloroallyl alcohols were also incubated in the water‐saturated subsoil material at 10°C. Again, a first stage with gradual transformation was followed by a second stage with fast transformation. In most instances, the concentrations had fallen to a very low level within three months. It was concluded that it is unlikely that residues in the upper groundwater would permeate into the deeper groundwater pumped up for public water supply.
Temperature effects on the action of acylurea insecticides against tobacco hornworm (Manduca sexta) larvae
Authors: Chandler Darren R. , King Robert G. , Jewess Philip , Reynolds Stuart E.
Published: November 2006

The toxic effects of six acylurea insecticides on larvae of the tobacco hornworm were investigated at each of four environmental temperatures (20, 25, 30 and 35°C). This spans the range of temperatures which the insects can tolerate. For all the acylureas tested, mortality increased with temperature when either newly hatched or fourth‐instar larvae were given insecticide in their food. Sub‐lethal growth inhibition also became more pronounced at progressively higher environmental temperatures. This temperature dependence of acylurea action was not due to altered uptake of the insecticide, since there was no significant variation with temperature in the amount of [14C]flufenoxuron taken up by fifth‐instar larvae when given a single meal containing labelled insecticide. Additionally, mortality of fourth‐instar larvae given a single intra‐haemocoelic injection of flufenoxuron was significantly greater at higher temperatures, implying that temperature affects a process that occurs after insecticide uptake. The intrinsic ability of acylureas to inhibit chitin synthesis is temperaturesensitive, since flufenoxuron inhibited the incorporation of [14C]N‐acetylalucosamine into chitin by proleg epidermis in vitro significantly less well at 20°C than at the higher temperatures tested. However, there was no significant variation between the effectiveness of in‐vitro chitin synthesis inhibition at 25, 30 and 35°C. These data show that the effectiveness of acylurea insecticides is subject to strong temperature effects in the range of temperatures likely to be experienced in the field.
Fungicidal β‐methoxyacrylates: From natural products to novel synthetic agricultural fungicides
Authors: Beautement Kevin , Clough John M. , de Fraine Paul J. , Godfrey Christopher R. A.
Published: November 2006

The strobilurins and oudemansins are natural β‐methoxyacrylates which inhibit mitochondrial respiration and, as a result, have fungicidal activity. A knowledge of the structures (configuration and conformation) and properties of these compounds has allowed the preparation of analogues in which both fungicidal activity and stability have been improved.
Light‐dependent herbicidal activity of 4‐pyridone‐3‐carboxanilide derivatives against Echinochloa oryzicola
Authors: Osabe Hirokazu , Morishima Yasuo , Goto Yukihisa , Masamoto Kazuhisa , Yagihara Hiroshi , Fujita Toshio
Published: November 2006

Novel 4‐pyridone‐3‐carboxanilide derivatives containing various substituents on the anilide benzene and 4‐pyridone rings were synthesized, and their herbicidal activity against Echinochloa oryzicola was evaluated. These compounds exhibited light‐dependent herbicidal activity, except for some 1‐N‐benzyl analogs substituted on the anilide moiety which were light‐independent. Among compounds synthesized, 5‐bromo‐2′,6′‐diethyl‐1,4‐dihydro‐2,6‐dimethyl‐4‐oxo‐1‐phenethylpyridine‐3‐carboxanilide was found to possess the highest light‐dependent herbicidal activity, being almost equivalent with that of oxyfluorfen. The effects of substituents of the anilide benzene and 4‐pyridone rings on the activity are discussed.
Comparative purification methods for determination of triadimenol residues in plant material
Authors: Reynaud Patricia V. , Rolle Sylvaine D. , De Cormis Louis
Published: November 2006

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.
Cipac collaborative study to test a colorimetric method for determination of the stability of dilute emulsions
Authors: Bernes Albert , Galoux Michel
Published: November 2006

A colorimetric method for the determination of the stability of dilute emulsions (down to 1 ml litre−1) of emulsifiable concentrates (EC) has been subjected to a collaborative study with 27 participating laboratories, on behalf of the Collaborative International Pesticides Analytical Council (CIPAC).

A dye is added to the emulsifiable concentrate and an aliquot is poured into standard water to obtain an aqueous emulsion. After a specified time, the absorbance of an aliquot of the dyed emulsion is measured and compared to the absorbance measured after initial formation of the emulsion.

Collaborators were furnised with four emulsifiable concentrate formulations and the dye, and requested to make three replicate determinations on each dyed sample in CIPAC standard waters A and D.

The repeatability and reproducibility figures obtained in these trials indicate that the method permits a good estimation of the stability of dilute emulsions when it is followed exactly.
Resistance to insecticides in winter‐ and summer‐forms of pear psylla, Psylla pyricola
Authors: Van De Baan Hugo E. , Croft Brian A.
Published: November 2006

Summer‐form pear psylla, Psylla pyricola Foerster, from sprayed pear were resistant to endosulfan (2·4‐fold), methiocarb (2·5‐fold), ethylan (5·8‐fold), azinphos‐methyl (7·7‐fold), and fenvalerate (40·1‐fold). Esterase (3·8‐fold), glutathione transferase (1·8‐fold), and cytochrome P‐450 monooxygenase (1·6‐fold) detoxification enzyme activity was higher in resistant than in susceptible summer forms. Synergism by piperonyl butoxide and S,S,S‐tributylphosphorotrithioate (DEF) was added evidence for cytochrome P‐450 monooxygenases and esterases as resistance mechanisms. Reduced penetration may also have contributed to resistance, as indicated by a 1·6‐fold slower penetration of azinphos‐methyl in resistant than susceptible summer‐forms. Similar differences in insecticide toxicity and esterase and glutathione transferase activities were observed between winter‐forms of resistant and susceptible pear psylla. Winter‐forms of P. pyricola were up to three times more tolerant to insecticides than summer‐forms. Higher cytochrome P‐450 monooxygenase activity (1·7‐fold) and slower azinphosmethyl penetration (2·1‐fold) in winter‐forms may have contributed to their greater insecticide tolerance; however, sequestration may also have been involved.
The influence of spray droplet characteristics on the efficacy of permethrin against the diamondback moth Plutella xylostella: The effect of drop size and concentration on the potency of ulv‐ and ec‐based residual deposits
Authors: Omar Dzolkhifli , Matthews Graham A. , Ford Martyn G. , Salt David W.
Published: November 2006

The effect of droplet diameter (36‐274 μm) and concentration (10‐400 g litre−1) of permethrin on the knockdown and mortality of 2nd‐instar Plutella xylostella larvae was investigated. Larvae were placed on brussels sprout leaf discs treated with residual deposits of permethrin applied as ULV or emulsion formulations. The LD50 of permethrin decreased with droplet size at all concentrations tested. This effect could not be accounted for solely by increased drop numbers per unit area of leaf, suggesting that for both formulations transfer of permethrin to larvae is more efficient for deposits composed of small drops. The concentration of permethrin in the ULV formulation could be reduced to approach a minimum quantity of toxicant per unit area to maintain 50 per cent mortality. The approach to the minimum dose varied with drop size and drop number per unit leaf area. The ULV formulation was approximately 2.7 times more effective at killing larvae than the emulsion, presumably as a result of greater availability of toxicant and transfer to larvae.
Excitation of central neurons by dieldrin and picrotoxinin in susceptible and resistant Drosophila melanogaster (meigen)
Authors: Bloomquist Jeffrey R. , Ffrench‐Constant Richard H. , Roush Richard T.
Published: November 2006

Neurophysiological studies were used to characterize the resistance mechanism in a new cyclodiene‐resistant strain of Drosophila melanogaster. Suction electrode recordings were taken from the peripheral nerves of transected larval central nervous system. Treatment of nerve preparations with 1 mM GABA reduced the spontaneous firing of peripheral nerves. This inhibition was effectively reversed within 10 min by exposing preparations from susceptible insects (Oregon‐R wild type) to 10 μM dieldrin. In contrast, 30 min incubations with 10 μM dieldrin had no effect on preparations from resistant individuals. At 10 μM, picrotoxinin was also effective in antagonizing the action of GABA in susceptible nerve preparations. In recordings from resistant insects (n = 3), picrotoxinin displayed either no antagonism of GABA‐dependent inhibition, weak antagonism of GABA, or hyperexcitation indistinguishable from those of susceptible preparations. These results demonstrate that cyclodiene resistance in the Maryland strain of D. melanogaster is present at the level of the nerve, and that the resistance extends to picrotoxinin, albeit at a reduced level. The possible role of an altered GABA receptor in this resistance is discussed.
Neuropharmacological studies of an insecticidal trihaloimidazole derivative in the crayfish neuromuscular preparation
Authors: Umeda Kimitoshi , Hirano Masachika
Published: November 2006

A trihaloimidazole derivative (S‐377; 1‐(4‐chlorobutoxymethyl)‐2,4,5‐trichloroimidazole) caused giant excitatory junctional potentials by a single electrical stimulus to the excitatory nerves. Repetitive discharges were simultaneously induced in the nerve fibres. S‐377 also caused repetitive firing in the inhibitory nerve fibres. Permethrin showed quite similar actions on both the junction and nerve fibres. It was supposed that S‐377 inhibited the inactivating system of the sodium channel, like pyrethroids. However, S‐377 reduced the number of spikes of the permethrin‐induced repetitive discharges on the excitatory nerve fibres. These observations suggest that binding sites of S‐377 on sodium channels are different from those of pyrethroids.
Distribution and activity of spray deposits in an oak canopy following aerial application of diluted and undiluted formulations of Bacillus thuringiensis Berliner against the gypsy moth, Lymantria dispar L. (Lepidoptera: Lymantriidae)
Authors: Van Frankenhuyzen Kees , Wiesner Charles J. , Riley Chris M. , Nystrom Carl , Howard Craig A. , Howse Gordon M.
Published: November 2006

The distribution and biological activity of spray deposits resulting from aerial applications of diluted and undiluted Bacillus thuringiensis, ‘Dipel 64AF’ against the gypsy moth, Lymantria dispar L., were examined in oak stands in south‐eastern Ontario, Canada. The sprays were applied by fixed‐wing aircraft equipped with four ‘Micronair AU4000’ atomizers. Application of diluted formulation at 30 BIU ha−1 in 6.0–6.4 litre generally resulted in a higher droplet density (10–28 cm −2 leaf) than application of undiluted product at the same dosage rate in 1.8 litre ha−1 (4–10 cm −2). However, spray deposits of undiluted product with a volume median diameter (Dv.5) of 90–130 μm caused as much mortality of gypsy moth larvae in bioassays of sprayed foliage as deposits of diluted product with a Dv.5 of 150–350 μm despite a two‐ to three‐fold reduction in droplet density. Our data suggest that by using fine spray atomization, undiluted application of these formulations can offer the same efficacy against gypsy moth as coarsely atomized sprays of diluted product.
An association between triazine resistance and powdery mildew resistance inEpilobium ciliatumandSenecio vulgaris
Authors: Clay David V. , Nash Caroline , Bailey John A.
Published: November 2006

The response of four naturally occurring biotypes ofEpilobium ciliatumand four sources of Senecio vulgaris to the herbicide atrazine were compared with their susceptibility to the powdery mildewsSphaerotheca epilobiiand Erysiphe cichoracearum. Biotypes that were resistant to atrazine were also resistant to mildew. Mechanisms that might explain the association between atrazine resistance and mildew resistance are discussed, along with possible implications of these findings for farmland ecology and for the production of herbicide‐ and mildew‐resistant crop plants.
Activity of fumaramidmycin mimics against oomycetes
Authors: Loubinoux Bernard , Gérardin Philippe , Kunz Walter , Herzog Jürg
Published: November 2006

Various fumaric acid derivatives have been prepared from the corresponding vinyl acylisocyanates. They exhibit interesting fungicidal activity, especially against the two important oomycetes Plasmopara viticola and Pythium ultimum.
Acaricidal and insecticidal activities of three synthetic oxazolidinones
Authors: Roberts Ralph R. , Williams Lawrence A. D.
Published: November 2006

The effects of three synthetic 2‐oxazolidinones were investigated on two arthropod pests: (1) Boophilus microplus (Canestrinii), the Southern cattle tick; and (2) Cylas formicarius elegantulus (Summer), a sweet potato weevil.
Structure‐activity relationships of triazinone herbicides on resistant weeds and resistant Chlamydomonas reinhardtii
Authors: Oettmeier Walter , Hilp Ursula , Draber Wilfried , Fedtke Carl , Schmidt Robert R.
Published: November 2006

Weeds resistant to the s‐triazine herbicide atrazine also show resistance to the triazinone herbicide metribuzin. However, with highly lipophilic triazinones, thylakoids isolated from atrazine‐resistant Amaranthus retroflexus (mutation at position Ser264 of the photosystem II D‐1 reaction centre protein) in general show a higher pI50 value in photosystem II electron transport than those from the wild type (i.e. negative cross‐resistance; ‘supersensitivity’). A quantitative structure–activity relationship (QSAR) can be established, wherein the lipophilicity of the compound plays a major role. In in‐vivo experiments, it was found that the triazinone DRW2698 killed resistant Amaranthus retroflexus and Chenopodium album whereas the wild type was almost unaffected. Triazinones were further investigated in five different mutants of Chlamydomonas rheinhardtii (mutations in the D‐1 protein at positions Ser264, Ala251, Leu275, Phe255, and Val219). Inhibitory activity of all triazinones was generally enhanced in the Phe255 mutant but decreased in the Val219 mutant. In the other mutants, biological activity was decreased when position 3 of the triazinone was substituted by CH3, OCH3, SCH3, NHCH3 or N(CH3)2. However, negative cross‐resistance was again observed when this position was occupied by free thiol. It is therefore suggested that these two groups of triazinones orient themselves differently within the herbicide binding niche of the photosystem II D‐1 protein.
Comparative fate in soil of the enantiomers of triadimenol when applied individually to barley seed
Authors: Clark Terence , Wong Wilson W.‐C. , Vogeler Klaus
Published: November 2006

The systemic fungicide triadimenol is a mixture of four enantiomers which have different biological activities. Dissipation and metabolism of the individual enantiomers in soil were investigated after seed treatment. Forty‐nine days after 1R2S and 1S2S treatments, more of the radioactivity (87% for both) had dissipated from the seeds into the 0–10 cm soil layer than after the 1S2R (76%) and 1R2R (73%) treatments. After 1R2S treatment 56% of the radioactivity extracted from soil was accounted for as the parent isomer and 44% as its 1R2R epimer. After 1S2R treatment 76% of the radioactivity was in the parent form and 24% was converted to the 1S2S (17%) and 1R2R (7%) isomers.
Pyrethroid resistance mechanisms in Australian Helicoverpa armigera
Authors: Gunning Robin V. , Easton Clive S. , Balfe Marjorie E. , Ferris Ian G.
Published: November 2006

In 1983, at the onset of pyrethroid resistance in Australian Helicoverpa armigera, three resistance mechanisms were identified. They were: a strong nerve insensitivity (Super‐Kdr), penetration resistance (Pen), and a factor which was overcome by piperonyl butoxide (PBO). Super‐Kdr nerve insensitivity appeared to be a major cause of pyrethroid resistance and contributed to high‐order resistance (> 100‐fold). From 1987 to 1990, to monitor the effect of the Australian Helicoverpa insecticide resistance management strategy on insecticide resistance, we conducted a survey of the frequencies of these mechanisms in field‐collected H. armigera. The relative importance of the Pen and Pbo mechanisms in resistant H. armigera have increased but Pen and Pbo confer only low order (∼ 20‐fold) resistance. We found no evidence of the 1983 Super‐Kdr mechanism in the latest samples, but, instead, found another distinct Kdr‐type mechanism. This mechanism was correlated with very low‐order nerve insensitivity and was of little toxicological significance. The impact of the Helicoverpa insecticide resistance management strategy on pyrethroid resistance in H. armigera is discussed.
Off‐target glyphosate from aerial silvicultural applications, and buffer zones required around sensitive areas
Authors: Payne Nicholas J.
Published: November 2006

Off‐target glyphosate deposits were measured downwind of aerial silvicultural applications which used D8‐46 hollow‐cone hydraulic nozzles, ‘Micronair’ AU 5000 rotary atomisers, and the ‘Thru Valve Boom’ (030), with volume application rates of 35, 20 and 20 litre ha−1respectively, and a glyphosate application rate of 2·1 kg ha−1. Crosswind spray lines were released 10 m above ground level over a short forest canopy, from a fixed‐wing aircraft flying at 45 m s1in atmospheric boundary layers with average wind speeds and air temperatures of 2·2‐3·7 m s−1and 8‐23°C at release height. Ground sheets and artificial foliage clusters were exposed at downwind distances of between 50 and 300 m. Glyphosate deposit measurements at various downwind distances (x) were fitted with non‐linear regression lines; deposits were attenuated at rates inversely proportional to x at powers of 1·3‐2·3. For a particular trial, deposits on ground sheets and artificial foliage were generally similar, and ranged between 19 and 0·04 mg m−2over the sampling distances used. For 100‐ha applications the estimated buffer‐zone widths around water bodies were less than 50 m, whereas those around non‐target vegetation ranged between 75 and 1200 m, depending on the application method and the meteorological conditions.
1(R)‐(2,6‐cis‐dimethylmorpholino)‐ 3(S)‐(p‐tert‐butylphenyl)cyclopentane: A representative of a novel, potent class of bio‐rationally designed fungicides
Authors: Huxley‐Tencer Alica , Francotte Eric , Bladocha‐Moreau Michelle
Published: November 2006

Inhibition of the Δ8‐Δ7 sterol isomerase in the ergosterol biosynthesis pathway is known to lead to fungistatic or even fungicidal effects. Our approach to the rational design of new putative inhibitors of the enzyme was based on the assumed mechanism of the enzymic transformation and in particular on the structure of the unstable carbocationic intermediate, i.e. the ‘transition‐state‐analogue’ principle. The synthesis and the biological properties of 1(R)‐(2,6‐cis‐ dimethylmorpholino)‐3(S)‐(p‐tert‐butylphenyl)cyclopentane, a representative of a novel, potent class of rationally designed fungicides, as well as the synthesis and biological activities of several other related compounds are described and discussed.
Some physicochemical factors influencing foliar uptake enhancement of glyphosatemono(isopropylammonium) by polyoxyethylene surfactants
Authors: Gaskin Robyn E. , Holloway Peter J.
Published: November 2006

Structure‐concentration–foliar uptake enhancement relationships between commercial polyoxyethylene primary aliphatic alcohol (A), nonylphenol (NP), primary aliphatic amine (AM) surfactants and the herbicide glyphosatemono(isopropylammonium) were studied in experiments with wheat (Triticum aestivumL.) and field bean (Vicia fabaL.) plants growing under controlled‐environment conditions. Candidate surfactants had mean molar ethylene oxide (EO) contents ranging from 5 to 20 and were added at concentrations varying from 0·2 to 10 g litre−‐1to [14C]glyphosate formulations in acetone–water. Rates and total amounts of herbicide uptake fromc. 0·2–μl droplet applications of formulations to leaves were influenced by surfactant EO content, surfactant hydrophobe composition, surfactant concentration, glyphosate concentration and plant species, in a complex manner. Surfactant effects were most pronounced at 0·5 g acid equivalent (a.e.) glyphosate litre−‐1where, for both target species, surfactants of high EO content (15–20) were most effective at enhancing herbicide uptake: surfactants of lower EO content (5–10) frequently reduced, or failed to improve, glyphosate absorption. Whereas, at optimal EO content, AM surfactants caused greatest uptake enhancement on wheat, A surfactants gave the best overall performance on field bean; NP surfactants were generally the least efficient class of adjuvants on both species. Threshold concentrations of surfactants needed to increase glyphosate uptake were much higher in field bean than wheat (c.2 g litre−‐1and < 1 g litre−‐1, respectively); less herbicide was taken up by both species at high AM surfactant concentrations. At 5 and 10 g a.e. glyphosate litre−‐1, there were substantial increases in herbicide absorption and surfactant addition could cause effects on uptake that were different from those observed at lower herbicide doses. In particular, the influence of EO content on glyphosate uptake was now much less marked in both species, especially with AM surfactants. The fundamental importance of glyphosate concentration for its uptake was further emphasised by experiments using formulations with constant a.i./surfactant weight ratios. Any increased foliar penetration resulting from inclusion of surfactants in 0·5 g litre−‐1[14C]glyphosate formulations gave concomitant increases in the amounts of radiolabel that were translocated away from the site of application. At these low herbicide doses, translocation of absorbed [14C]glyphosate in wheat wasc.twice that in field bean; surfactant addition to the formulation did not increase the proportion transported in wheat but substantially enhanced it in field bean.
The use of ecotoxicological risk assessment in deriving maximum acceptable half‐lives of pesticides
Authors: Van Straalen Nico M. , Schobben John H. M. , Traas Theo P.
Published: November 2006

Approaches in ecological risk assessment are usually based on estimating the probability that organisms will be exposed to environmental concentrations of chemicals greater than some toxicological criterion (LC50, NOEC). Following this approach, quality standards for persistent chemicals in soil can be derived. For readily degradable chemicals emitted at intervals, the ecological risk can be related to the time taken for the chemical concentration to fall to a level causing no effect on most, e.g. 95%, of the species. A formula is derived for the maximum acceptable half‐life, assuming a log–logistic distribution of species susceptibilities and a simple exponential decay of the chemical. It is also assumed that the pesticide is distributed homogeneously through the top 20 cm of the soil. A numerical example is elaborated for carbofuran, demonstrating that for a recommended dose applied to soil, the maximum half‐life should be 47 days, if the ecotoxicological protection level is to be reached within one year after a single application. This estimate may vary between 35 and 61 days, depending on the margins of uncertainty attached to ecotoxicological data. Complete recovery not only includes the disappearance of the chemical but also the recolonization of treated soils. The half‐life condition derived in this paper should therefore be considered as a minimum requirement.
Studies on wetting phenomena on plant leaf surfaces. 3: A retention model for droplets on solid surfaces
Authors: Watanabe Tadakazu , Yamaguchi Isamu
Published: November 2006

To investigate the factors governing retention of pesticidal spray solutions on plant surfaces, a new retention model for droplets on solid surfaces has been introduced as

magnified image

where ΔΘ = Θa – Θr. The minimum sliding volumes (MiSV) of surfactant aqueous solutions (2 g litre−‐1; surface tensions; 28·5 – 72·5 mN m−‐1) on smooth surfaces of paraffin wax and polymer sheets were measured and the validity of the above retention equation was verified on combinations of these solutions and surfaces. A concept of the specific adhesional force (Fa) of a droplet was defined as

magnified image

which was the maximum adhesional force on a unit length of the width of the contact circle of a droplet, and Fa values of the solutions on the surfaces were compared. The predominant factors for droplet retention are discussed on the basis of this model.
Determination of the sulfonylurea herbicides chlorsulfuron and metsulfuron‐methyl in soil, water and plant material by gas chromatography of their pentafluorobenzyl derivatives
Authors: Cotterill Edward G.
Published: November 2006

The measurement of the sulfonyl urea herbicides, chlorsulfuron and metsulfuron‐methyl as pentafluorobenzyl derivatives has been investigated and the kinetics of reaction optimised. The reaction product was identified by mass spectroscopy as N,N‐bis(pentafluorobenzyl)‐2‐chlorobenzenesulfonamide. Amounts of herbicide derivative as low as 0·1 pg per injection can be detected. Suitable conditions for both packed and capillary chromatography are given. Application of the method to residue determination is discussed and the method is shown to be suitable for residues in soil and water but less so for plant material.
Methyl bromide in natural fresh waters: Hydrolysis and volatilisation
Authors: Gentile Irene Abbattista , Ferraris Lucia , Sanguinetti Mario , Tiprigan Marinela , Fisichella Giuseppina
Published: November 2006

The effect of some physical factors on the processes (hydrolysis, volatilisation) regulating the persistence of methyl bromide in fresh surface waters was investigated to complement previous research.

It has been confirmed that electromagnetic radiation in the visible field has no influence on the hydrolysis kinetics of the fumigant.

The removal of methyl bromide by volatilisation from stirred and ventilated solutions appears to be of greater importance in practice. It has been shown that under these conditions the half‐life is directly proportional to the liquid depth.

Without stirring volatilisation is greatly reduced, due to the low diffusivity of methyl bromide in the aqueous phase.
Towards the rational design of crop protection agents
Authors: Goosey Michael W.
Published: November 2006

The crop protection industry has consistently provided new and improved products during the past forty years. The discovery process has, to a large extent, relied upon empirical procedures and imitative chemistry to generate these compounds. Although these methods will continue to be employed, it is envisaged that additional technology will be incorporated into the process and in this respect the development of molecular biology, computational sciences and biophysical techniques is discussed. The successful integration of these skills requires an open and communicative environment involving multi‐disciplinary research groups.
Simulation modelling to assess the potential value of formulation development of lambda‐cyhalothrin
Authors: Day Roger K. , Collins Martyn D.
Published: November 2006

Simulation modelling was undertaken to investigate the likely practical benefits of more persistent formulations of a synthetic pyrethroid for control of Heliothis sp. on cotton. A model was built describing mortality to first‐instar Heliothis larvae on cotton during the period following a spray application and used to evaluate the influence of formulation type on persistence of effect. The product used in the study was lambda‐cyhalothrin. Data for the model were gathered principally from published and unpublished reports. Two parameters were used to describe a formulation; the half‐life of the biologically active residue, and the toxicity relative to a standard formulation. To achieve a 50% increase in persistence of effect, defined as days' mortality above 50%. it was necessary to treble the values of both parameters. Persistence of effect was more sensitive to the way in which larvae were distributed over the plant than to the growth rate of the plant but the relative increase in persistence of effect from improved formulation was robust to changes in larval distribution and plant growth.
Evaluation of the membrane approach to solid‐phase extractions of pesticide residues in drinking water
Authors: Davi Letizia M. , Baldi Massimo , Penazzi Luciano , Liboni Michelina
Published: November 2006

The purpose of this work was to compare the method and analytical results obtained by liquid/liquid extraction with those of solid‐phase extraction, in particular with the use of an Empore disc, in the investigation of pesticide residues in drinking water.
Spectrophotometric determination of ferric dimethyldithiocarbamate (ferbam) in formulations, grain and apples using 1, 10‐phenanthroline
Authors: Malik Ashok Kumar , Rao A. L. J.
Published: November 2006

A procedure has been developed for the determination of ferbam (ferric dimethyldithiocarbamate) by converting it into ferbam‐phenanthroline complex, which is dissolved in acetone + water (1 + 1 by volume), and the absorbance measured at 490 nm against a reagent blank. Beer's law is obeyed over the concentration range 0–8–20‐0 mg litre−1 in the final solution. The method is sensitive, selective and can be used for the direct determination of ferbam in commercial samples, in mixtures with various other dithiocarbamates (ziram, zineb, maneb, etc.) and from grains (rice and wheat) and apples. The limit of determination from foodstuffs is 0–4 mg kg−1.
Synthesis and bioactivity of some fluorine‐containing benzoyl arylureas. Part II: Insecticidal products in which the aryl group bears a polyfluoroalkoxy or (polyfluoroalkoxy)alkoxy side chain
Authors: Rama Franco , Meazza Giovanni , Bettarini Franco , Piccardi Paolo , Massardo Pietro , Caprioli Vincenzo
Published: November 2006

This paper reports the synthesis and insecticidal activities of benzoyl arylureas in which the aryl group bears a polyfluoroalkoxy or (polyfluoroalkoxy)alkoxy side‐chain. The activity of these compounds has been evaluated against larvae of S. littoralis, A. aegypti and L. decemlineata.

The effects have been studied of varying (a) the substituents, R1 and
R2 in the 2‐and 6‐positions of the benzoyl moiety; (b) the polyfluoroalkoxy chain R1 in the 4‐position of the aryl moiety; and (c) the other substituent(s), R3, on this ring.

In general, the highest activities were achieved against S. littoralis when R1, R2 = F, R3 = 2‐F and R1 = OCF2CFHOCF3 or R1 = Cl and R2 = H. R3 = 2‐Cl and R1 = OCF2CFHOCF3; against A. aegypti when R1, R2 = F. R3 = 3‐F and R1 = OCF2CFHOCF3 or R1 = Cl and R2 = H. R3 = 3‐F and R1 = OCF2CFHOCF3; and against L. decemlineata by compounds in which R1 = Cl and R2 = H. R3 = 3. 5‐CI and R1 = OCF2CFHOCF3, R1, R2 = F, R3 = 3.5‐Cl and R1 = OCF2CFHOCF2CF3, R1, R2 = F, R3 = 3‐CI and R1 = OCF2CFHOCF2CF2CF3. The greatest overall insecticidal activities were achieved when R1, R2 = F, R3 = 2‐F and R1 = OCF2CFHOCF3 and when R1, R2 = F, R3 = 3‐Cl and R1 = OCF2CFHOCF3.
Activity of adjuvants in ‘aliette’ against Botryotinia fuckeliana (botrytis cinered) and their cross‐resistance with benzimidazole fungicides
Authors: Faretra Francesco , Pollastro Stefania , Sansiviero Francisco
Published: November 2006

‘Aliette’, a formulation of the fungicide fosetyl‐aluminium, is moderately active in vitro against the ascomycete Botryotinia fuckeliana (Botrytis cinerea). In contrast, fosetyl‐aluminium and related chemicals, such as phosphonic acid and sodium phosphonate, have low efficacy, although it is enhanced by media with low phosphate content. This indicates that the effectiveness of ‘Aliette’ against B. fuckeliana is not due to fosetyl‐aluminium but to adjuvants included in the formulation.

The genetic basis of differences in sensitivity to ‘Aliette’ was investigated in field and laboratory isolates of B. fuckeliana. Genetic analysis showed that reduced sensitivity to ‘Aliette’ always co‐segregated with resistance to benzimidazole fungicides in meiotic progeny of sexual crosses. This indicates that differences in sensitivity to ‘Aliette’ in B. fuckeliana are due to the major gene Mbcl of resistance to benzimidazole fungicides and active adjuvant(s) present in ‘Aliette’ are linked to benzimidazoles by cross‐resistance.
Fenitrothion‐induced alterations in ammonia metabolism in the crab, Oziotelphusa senex senex fabricius
Authors: Reddy Pamanji Sreenivasula , Bhagyalakshmi Avilala
Published: November 2006

Fresh water crabs, (Oziotelphusa senex senex) were subjected to short‐term (1 day) and long‐term (30 days) exposure to a sublethal concentration of fenitrothion (0.04 mg litre‐1), and the hepatopancreatic nitrogen metabolism was investigated. Differential patterns of nitrogen metabolism were observed in the hepatopancreas in response to both short‐term and long‐term exposure. Levels of ammonia in hemolymph of crab after short‐term exposure were markedly increased, with an increase in excretion of ammonia. The activity levels of aspartate aminotransaminase (AAT), alanine aminotransaminase (AIAT) and glutamate dehydrogenase (GDH) were found to increase in the hepatopancreas during short‐term exposure, which suggests increased transamination and deamination of amino acids. The AMP‐deaminase activity increased in the hepatopancreas during short‐term exposure indicating increased deamination of nucleic acids. The activity levels of ornithine cycle enzymes such as arginino succinate synthetase (ArSS) and arginase indicated diminished activities resulting in a low level of operation of the urea cycle and consequent accumulation of ammonia during short‐term exposure. The whole view of ammonia production and utilization mechanisms suggests the probable synergistic manifestation of ammonia toxicity during short‐term fenitrothion poisoning.

However, during long‐term exposure, the haemolymph had a low ammonia level. The excretion of ammonia was also found to decrease. The activity levels of AAT, AIAT and GDH in the hepatopancreas were found to increase. In contrast to these, the AMP‐deaminase activity decreased in the hepatopancreas suggesting decreased deamination of nucleic acids. ArSS and arginase activities increased indicating active operation of the urea cycle and consequent accumulation of urea. Glutamine synthetase activity rose with the accumulation of glutamine which may help in averting toxic effects of ammonia. The possible effects of fenitrothion toxicity on energy requirements, transdeamination patterns, ureogenesis and glutamine production have been discussed.
Evaporation and Uptake of the Herbicide 2,4‐ D‐Butyl Applied to Barley Leaves
Authors: Breeze Victor G. , Simmons Joanna C. , Roberts Matthew O.
Published: November 2006

Simultaneous measurements were made of evaporation and foliar uptake of formulated [2‐14C]2,4‐D‐butyl, applied as 10‐μl droplets to the leaves of three‐week‐old barley plants, at different temperatures and boundary layer conductances using an air‐flow system. Evaporation was measured both by trapping the vapour and by the difference between the amount applied and the amount recovered from the plant. Assimilation of vapour by the plants during the experimental periods of about 6 h was found to be about 0·4% of the total amount of herbicide applied initially to the leaves. Uptake and evaporation were described in terms of rates and velocity constants. Uptake was generally the more rapid, by about 2·5 times, of the two processes. Temperature affected evaporation strongly whereas uptake was largely unaffected. Kinetics of evaporation from glass slides and leaf surfaces were very similar if surface temperature was taken into account. Evaporation from leaves increased in darkness and in conditions of high boundary layer conductance caused by rapid air circulation. The importance of the boundary layer has been underestimated in previous studies, and some misleading results have been reported as a consequence. Most of the herbicide that penetrated the plant (95%) remained in the leaf to which it was applied, but it affected physiological processes within the plant because transpiration and carbon dioxide exchange were reduced by about 8 and 18%, respectively. Comparison with published values of herbicide uptake suggested that 2,4‐D‐butyl is relatively rapidly taken up by barley leaves. Results predicted that, at 27°C, about 30% of the 2,4‐D‐butyl sprayed onto barley leaves would evaporate, and 70% would remain in the plant.
Knowledge‐based systems for pest management: an applications‐based review
Authors: Edwards‐Jones Gareth
Published: November 2006

Since the first application of artificial intelligence (AI) techniques to agricultural problems in 1982 nearly 300 further systems have been reported, of which 50 have been developed for pest management. Typically, these systems perform one of three tasks; diagnostics, treatment prescription or strategy development. The characteristics of all three types of system are discussed with reference to several examples. Although these examples serve to emphasise the power of AI techniques for aiding management decisions, few existing agricultural knowledge‐based systems utilise this potential to the full, and as yet there has not been a widespread adoption of this technology by practising pest managers. Despite the failure to transfer this technology from the laboratory to the field, the potential of knowledge‐based systems is widely recognised. However, further development of this technology for agricultural use within the UK is likely to be hindered by funding constraints.
Aspergillus niger and a Penicillium sp. are not directly involved in the degradation of chlorsulfuron
Authors: Stevens Melita , Duxbury Trevor
Published: November 2006

When Aspergillus niger or a Penicillium sp. were grown in potato dextrose broth supplemented with chlorsulfuron, the herbicide concentration decreased by 97–99% within 78–96 h and the pH of the medium fell from 7.2 to between 2.4 and 3.1. If, during growth, the pH was maintained at or near neutrality, no decrease in herbicide concentration occurred. When sterile medium containing the herbicide was titrated with acid to mimic acid formation during fungal growth, the herbicide concentration again declined. Precipitation was not responsible for the observed decrease. The data indicate that, in laboratory media, these fungi do not directly metabolise the herbicide as previously thought. Chlorsulfuron degradation in perfused soil cores was not enhanced by inoculation with A. niger. Our results show that A. niger and a Penicillium sp. do not degrade chlorsulfuron.
Comparison of the impact of a neem seed‐kernel extract formulation, “Margosan‐O” and chlorpyrifos on non‐target invertebrates inhabiting turf grass
Authors: Stark John D.
Published: November 2006

Several laboratory studies have indicated that neem seed‐kernel extracts, or the neem insecticide azadirachtin, are active against certain types of pestiferous insects but do not harm several types of beneficial arthropods. The abundance of several groups of invertebrates inhabiting a turf grass ecosystem was determined in 1991 after application of a neem‐based insecticide formulation, “Margosan‐O®” (MO; W. R. Grace & Co., Columbia, Maryland, USA) containing 3.0 g litre−1azadirachtin, and chlorpyrifos. MO was less detrimental than chlorpyrifos to most of the invertebrates studied. However, oribatid mites were more sensitive to MO than to chlorpyrifos. Sminthurid and non‐sminthurid collembola were also susceptible to MO, although less so than to chlorpyrifos. MO had no significant effect on non‐oribatid mites and spiders. Environmental implications of using selective versus broad‐spectrum insecticides in agriculture are discussed.