bluuebunny/crossref_metadata_2025 huggingface dataset:
Action of pesticides on earthworms. Part IV: Uptake and elimination of oxamyl compared with carbofuran
Authors: Stenersen JØRgen , Øien Nils
Published: November 2006

Uptake and excretion of the two carbamates, oxamyl and carbofuran, which differ greatly in their toxicity to earthworms, were studied in one worm species; the metabolism of oxamyl was studied in six worm species. Carbofuran was taken up by the worms at a much higher rate (13 times greater) than oxamyl when the worms were dipped in aqueous solutions of the pesticides. The relative rates of elimination were the same (half‐life 2.5 h). Metabolism of oxamyl was low in all the earthworms studied. The low rate of uptake may therefore be the main factor for the safety of oxamyl in respect of these important non‐target organisms.
The effect of the fruit container on a commodity treatment of mangoes with 1,2‐dibromoethane against the queensland fruit fly, Dacus tryoni (froggatt)
Authors: Swaine Gordon , Corcoran Robert J. , Cranny Anne E. , Davey Marguerite A.
Published: November 2006

Fruit packed in fibreboard cartons required a higher dosage of 1,2‐dibromoethane (EBD) for an effective commodity treatment than fruit packed in polystyrene trays. This was due to considerably greater sorption of EDB by fibreboard compared with polystyrene, as indicated by concentration‐time products. However, compensating factors in the form of a lower sorption of EDB by the fruit itself when in fibreboard cartons, and a residual fumigant effect for fruit in such cartons, reduced the expected increase in dosage requirement. The required dosages of EDB for effective treatments were 20 g m−3 in fibreboard cartons and 16 g m−3 in polystyrene trays, for 2 h at 20°C.
Dissipation rates of insecticides in six minor vegetable crops grown on organic soils in Ontario, Canada
Authors: Braun Heinz E. , Ritcey Gwen M. , Frank Richard , McEwen Freeman L. , Ripley Brian D.
Published: November 2006

Dissipation rates of diazinon, endosulfan, leptophos, methamidophos, methomyl, parathion and pirimicarb were studied on five minor vegetable crops, including cos and head lettuce, endive, cauliflower and Chinese cabbage. Residues from foliar treatment generally followed an exponential rate of decline. The number of days for residues to drop to below acceptable tolerances was highly dependent on the magnitude of the initial residue; large variations in initial residues were observed between years, between insecticides, and between crop types. Residues of five insecticides and two fungicides used in furrow treatments for onions intended for pickling were determined in the onions at harvest and after pickling. Fensulfothion and fonofos levels were below the accepted tolerance of 0.1 mg kg−1 at harvest, while chlorfenvinphos, chlorpyrifos and ethion were present above this level; fungicide residues were not detected. Following pickling, only ethion residues were still present in the onions at levels greater than 0.1 mg kg−1.
Cross‐resistance spectrum in pyrethroid‐resistant Culex quinquefasciatus
Authors: Priester Thomas M. , Georghiou George P.
Published: November 2006

Strains of Culex quinquefasciatus Say, selected with biopermethrin [(1R)‐trans‐permethrin] or with (1R)‐cis‐permethrin, were examined in the larval stage for crossresistance to 30 pyrethroids, DDT, dieldrin, temephos, propoxur, and two organotin compounds. The (1R)‐trans‐Permethrin‐R strain [resistance factor (RF) = 4100‐fold] and the (1R)‐cis‐Permethrin‐R strain (RF= 450‐fold) of C. quinquefasciutus were cross‐resistant to all pyrethroids tested [RF= 12‐fold for an allethrin isomer to about 6000‐fold for (RS,RS)‐fenvalerate] as well as to DDT (RF= about 2000‐fold). However, they were not significantly Cross‐resistant to dieldrin, temephos, propoxur, and the two organotin compounds. Changes in the alcohol moiety, structural isomerism, and susceptibility of the cyclopropane C‐3 side chain to oxidative attack are important factors in determining the level of cross‐resistance to various pyrethroids. Limited synergism of the pyrethroids by S,S,S‐tributyl phosphorotrithioate and piperonyl butoxide (PB), and of DDT by chlorfenethol and PB, suggested that some non‐metabolic mechanism, such as kdr, may be an important component of resistance to pyrethroids as well as to DDT in this mosquito.
Dissipation rates in soil of 1,2‐dichloropropane and 1,3‐ and 2,3‐dichloropropenes
Authors: van Dijk Hendrik
Published: November 2006

The rates of dissipation in soil and chloride‐ion release, of the main components of dichloropropane‐dichloropropene mixtures used as nematicides, were studied in sealed glass containers at different temperatures and moisture conditions. Half‐lives of (Z)‐ and (E)‐1,3‐dichloropropenes at 20°C in soils were found to vary from 3 to 25 days; those of 1,2‐dichloropropane and 2,3‐dichloropropene were about four times and twice as long, respectively. The dissipation rates changed by a factor of about 2 per 10°C change in temperature. Judging from the release rates of waterextractable inorganic chloride in the soil (0‐4% per week), the total degradation of all components applied at normal field rates was extremely slow. This indicated the formation of residues containing covalently bound chlorine. Only in ‘enrichment cultures’ was complete degradation indicated.
Simulation of herbicide persistence in soil; a revised computer model
Authors: Walker Allan , Barnes Anthony
Published: November 2006

Empirical equations were used to calculate the moisture content of surface soil from measurements of rainfall and daily maximum and minimum air temperatures. Air temperatures were also used to calculate soil temperatures. There was good agreement between calculated and measured moisture contents and temperatures from Wellesbourne and from some sites in North America. The equations were incorporated into a simulation model for the prediction of herbicide persistence. Results from the model were essentially the same, whether calculated or measured soil moistures and temperatures were used in the calculations.
The extraction, estimation and persistence of benodanil fungicide in tobacco tissues
Authors: Cole James S. , Zvenyika Zvenyika
Published: November 2006

The results of determinations of benodanil, extracted with acetone from freeze‐dried tobacco leaves and estimated by thin‐layer chromatography and bioautography, correlated well with those obtained by Soxhlet‐extraction with acetone‐light petroleum and determined by gas‐liquid chromatography. A greater percentage of the amounts applied was usually recovered from leaves than from stems and more was always recovered 10 days after application than after 1 day. Similar changes in extractability with time were found in field samples; less was extracted from roots, stems and leaves at transplanting (2 days after treatment) than several days later. Comparatively large amounts of benodanil were present in roots, stems and leaves, 4 weeks after transplanting, and stem damage from Rhizoctonia solani was restricted.
A review of methods for the determination of polychlorodibenzo‐p‐dioxins and polychlorodibenzofurans in phenoxyalkanoic acid herbicides
Authors: Baker Paul G. , Hoodless Richard A. , Tyler Joseph F. C.
Published: November 2006

A review is presented of the analytical methods for the detection and determination of polychlorodibenzo‐p‐dioxins and polychlorodibenzofurans in phenoxyalkanoic acid herbicides.
Preparations for the treatment of pruning wounds
Authors: Gendle Peter , Clifford Derek R. , Mercer Peter C.
Published: November 2006

Benodanil, triadimefon or triadimenol, prepared as solutions (30 g litre−1) in a mixture of N‐methyl‐2‐pyrrolidone and xylene(1+ 9 by volume), or benodanil, prepared by diluting an emulsified concentrate with water, were applied to the surface of stumps produced by removing branches from apple trees. The active ingredients penetrated in fungitoxic amounts at least 6 cm below the wound surface, except when diluted benodanil e. c. was used. No such penetration occurred when the stumps were treated with acrylic paints containing the same ingredients. Triadimefon and triadimenol persisted within the wood for at least 273 days. No treatment inhibited callus formation but none appeared to enhance it. There were more saprophytic fungi in samples taken from treated than from untreated stumps, and the number of microorganisms present in the wood decreased with distance from the wound surface. Only one basidiomycete fungus was present in wood samples taken 273 days after treatments were carried out.
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

Photolysis 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

2‐(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

The 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

Petroleum 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

The 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

Residues of endosulfan insecticide (α‐ and β‐isomers, and ‘endosulfan sulphate’) in fish and their predators were measured during and after operations to control tsetse fly in the Okavango Delta, Botswana. Six ultra‐low‐volume doses of endosulfan 35% e.c. (6–12 g a.i. ha−1) were applied from the air in a period of 12 weeks over 2500 km2. The concentration of residues found in living fish was up to 0.19 mg kg−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

Larvae 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

Nine 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

Extensive 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

The 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

Photochemical 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

The 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

A 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

Amounts 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

The chitin synthesis inhibitor diflubenzuron, applied as a wettable powder spray to woven polypropylene at 100–500 mg m−2, was effective against Dermestes maculatus De Geer for at least 12 weeks. D. maculatus was unable to develop on ox hide dipped in a suspension of diflubenzuron (125 mg litre−1), or on fishmeal dusted at 1–10 mg of active ingredient kg−1. Diflubenzuron prevented the development of infestations of Callosobruchus maculatus (L.) on peas and of Acanthoscelides obtectus (Say) on beans dusted at 1–5 mg kg−1. The compound was also very effective against early instar larvae of Trogoderma granarium Everts on wheat. The persistence and activity of diflubenzuron at low dosage rates against D. maculatus appear to justify larger scale trials.
Changes induced by phorate in the carbohydrate metabolism of the snail Lymnaea acuminata
Authors: Mahendru Vijay K. , Agarwal Ram A.
Published: November 2006

Carbohydrate 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

Gas‐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

Estimates 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

The 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

Larvae 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.
Spectroscopic investigation of electron donor‐acceptor processes involving organic free radicals in the adsorption of substituted urea herbicides by humic acidsa
Authors: Senesi Nicola , Testini Ciro
Published: November 2006

Products of the interaction between soil humic acids and substituted‐urea herbicides were prepared in the laboratory and subjected to elemental, functional group, differential thermal, infrared spectroscopic and electron‐spin resonance analysis, in order to examine the various chemical mechanisms that may take place upon adsorption. The results indicate that, besides the involvement of hydrogen bonding, a prominent role is played by electron donor‐acceptor processes involving organic free radicals, which leads to the possible formation of charge‐transfer complexes. The phytotoxicity of the urea herbicides, expressed as the inhibition potency towards the Hill reaction (pl50 values), appeared to be correlated with their capacity to interact with soil humic components, and it is suggested that these two processes depend upon the same molecular parameters.
Evaluation of inexpensive thin‐layer chromatographic procedures for the estimation of some organophosphorus and carbamate insecticide residues in fruit and vegetables
Authors: Wood Alan B. , Kanagasabapathy Lalitha
Published: November 2006

Modified versions of previously published procedures for the extraction and clean‐up of some organophosphorus insecticide residues in fruits and vegetables are described, and their usefulness in combination with selected thin‐layer chromatographic procedures is experimentally assessed for several pesticides in apples, oranges, tomatoes, carrots and peas. A simple extraction procedure for insecticidal carbamates is similarly evaluated for carbaryl and propoxur residues in apples, carrots and peas. Semi‐quantitative estimation, by visual comparison with standards, is shown to be possible in many cases at residue levels as low as 0.4 mg kg−1, and the combined procedures should be useful in the screening of fruits or vegetables for compliance with maximum residue limits.
Chemical control of soil‐borne pathogens in tuff medium for strawberry cultivation
Authors: Sneh Baruch , Katan Jaacov , Abdul‐Raziq Ali
Published: November 2006

The phytopathogenic fungi Fusarium oxysporum f. sp. lycopersici and Rhizoctonia solani were completely eradicated after exposure for 30 min to a 0.4‐0.5 % aqueous solution by weight of formaldehyde. With metham‐sodium, higher concentrations or longer exposures were needed to obtain similar results. When tested in tuff (a granular plant growth medium of volcanic rock origin), the toxicity of formaldehyde was lower and that of metham‐sodium was higher, compared with the corresponding toxicities in aqueous solutions. Both fungicides eradicated the two fungi, as well as Pythium myriotilum, when tested under practical conditions in vertical aluminium tubes filled with tuff. No detrimental effect could be observed on strawberry plants subsequently grown in these columns.
The effects of temperature and humidity on the toxicity of three organophosphorus insecticides to adult Oryzaephilus surinamensis (L.)
Authors: Barson Graham
Published: November 2006

The toxicities, to a laboratory susceptible strain and to a resistant strain of Oryzaephilus surinamensis (L.), of water‐dispersible powder formulations of pirimiphos‐methyl, fenitrothion or chlorpyrifos‐methyl under constant conditions of 25°C and 70% r. h. were compared to the toxicities when the insects were exposed to a diurnal cycle of 12.5–20–12.5°C and 70–50–70% r. h. to simulate grain store conditions in the UK during spring and autumn. All the insecticides were more effective at 25°C and 70% r. h. The LD50 values for the susceptible strain were low, being 4.4 and 1.4 mg m−2 at 12.5‐20°C and 25°C, respectively, for chlorpyrifos‐methyl, 18.3 and 4.1 mg m−2, respectively, for pirimiphos‐methyl, and 4.0 and < 1.O mg m−2, respectively, for fenitrothion. The LD50 values obtained from the two sets of environmental conditions for a resistant strain (484) differed by factors of 1.8 for chlorpyrifos‐methyl, 4.8 for pirimiphos‐methyl, and 7.3 for fenitrothion.

Toxicity studies were also made with chlorpyrifos‐methyl under various constant conditions of temperature and humidity from 5–30°C (5°C intervals) and 30, 50, 70 and 90% r. h., and also at O°C and 60% r. h.

Chlorpyrifos‐methyl was very effective and there was little or no cross resistance to chlorpyrifos‐methyl in the resistant strain. From 15 to 30°C, mortality was high, and differences in mortality at the LD50 level for the various humidities were slight, but there was a decrease in mortality with decreasing humidity at any one temperature, in particular, at 5°C, 50 and 70% r. h., and 10°C and 50% r. h. Chlorpyrifosmethyl was more toxic to both strains at the highest humidity (90%) throughout the whole temperature range. The LD50 values for each strain decreased at each temperature as the water vapour concentration was increased. At O°C and 60% r. h., all the insects from both strains died but the cause of death was not clear.
A test for repellency to non‐biting flies and a comparison of repellents using Musca domestica L.
Authors: Campbell Malcolm M.
Published: November 2006

A system for testing the effect of a repellent against nonbiting flies attracted to man was developed for Musca domestica L. and Musca vetustissima Walk., and was used to compare the repellency of a range of chemicals against the former. Both arms of one person were simultaneously exposed to large numbers of the test insect in a cage, with repellent applied to a 45 cm2 area on one arm, and the solvent to an identical area on the other arm. By varying the dose of repellent, a dose‐to‐repellency relationship was established and evaluated using probit analysis to determine 50% (RD50) and 90% (RD90) repellency. Both values were required to characterise a repellent. Greatest uniformity of results was obtained with even illumination of the cages from above and exclusion of side lighting. RD50 and RD90 values were not affected by prior exposure of the flies in a cage and did not change with time. Of the repellents tested, dipropyl isocinchomeronate was the most effective against M. domestica. The repellent effect of mixtures of the compounds was tested against M. domestica and was less than expected by summation of the components acting alone, suggesting that to minimise the total dose of chemical applied to skin, single compounds are preferable to mixtures.
New possibilities for controlling foliar absorption via stomata
Authors: Mansfield Terence A. , Pemadasa Malawara A. , Snaith Paul J.
Published: November 2006

Stomatal guard cells are known to be preferential sites for foliar absorption. Uptake of herbicides has been shown to increase when the stomata are open, probably because the pore provides access for solutions to areas where the cuticle is thinner and where less wax is deposited. Stomatal closure in dry seasons has been suggested as a reason for reduced herbicide uptake in those periods. New evidence is presented that indol‐3‐ylacetic acid can overcome the influence of natural agents causing stomatal closure, thus providing the possibility of regulating stomatal aperture in the field to facilitate the uptake of applied chemicals.
Phytotoxicants from microorganisms and related compounds
Authors: Fischer Hans‐Peter , Bellus Daniel
Published: November 2006

Phytotoxic compounds produced by microorganisms are reviewed. Their utilisation as leads to new herbicides is explored in three chemical classes : 2‐aminoalk‐3‐enoic acids, ether derivatives of 3‐hydroxycyclobut‐3‐ene‐1,2‐diones, and 2‐(acylaminooxy)acetic acid derivatives. It is concluded that some bacteria and fungi yield compounds possessing sufficient herbicidal activity to be valuable as herbicides as such, or as leads for chemical optimisation.
Effect of fungicides on stages of the life cycle of Phytophthora cinnamomi
Authors: Geissler Art E. , Katekar Gerard F.
Published: November 2006

An assessment was made of the effects of several fungicides on the formation of zoosporangia, the release of zoospores from zoosporangia, zoospore motility, germ tube formation and mycelial growth, by Phytophthora cinnamomi Rands. Compounds active against mycelial growth (such as metalaxyl and furalaxyl), as well as those active against zoospores (such as captafol and zineb), could be detected by a lupin (Lupinus angustifolius L.) assay which has been developed. This assay may be useful as a screening procedure to detect new fungicides.
Atrazine hydrolysis. Part I: Proton catalysis at 25°C
Authors: Gamble Donald S. , Khan Shahamat U. , Tee Oswald S.
Published: November 2006

Six new results have been obtained in an investigation of the catalysed hydrolysis of atrazine. A procedure was developed for determining rate constants from the first 20 mol% of the reaction. The reduced length of the experiments increased the experimental productivity and minimised the risk of sample deterioration. The proton catalysis rate was measured at 25°C, over the H+ concentration range of 1 to 10 mmol litre−1. This shortened the extrapolation to the pH values of field conditions, and guaranteed the absence of doubly‐protonated atrazine. Because spectrophotometry has been regarded as a controversial method for studying the hydrolysis kinetics of the 1,3,5‐triazine herbicides, this method was re‐examined. Excellent agreement was obtained from a comparison of the gas‐liquid chromatographic and spectrophotometric methods of monitoring the kinetics experiments. Of the widely diverging relationships found in the literature for the extrapolation of laboratory half‐lives to the pH range of field conditions, the one deduced from the reaction scheme of Plust et al. was found to be theoretically correct. Its parameters have been calibrated with several hundred experimental measurements. The proton is not the dominant catalytic agent in soils, but its calibration is essential for identifying those catalytic agents that are dominant. It has been deduced that the temperature dependence of the experimental rate constant is governed by the temperature responses of two parameters.
Synthesis, fungicidal activity and structure‐activity relationships of a series of 1‐(3‐pyridyl)‐1‐substituted‐but‐3‐yn‐1‐ols
Authors: Arnoldi Anna , Betto Eliseo , Ceresa Lucia , Farina Gandolfina , Formigoni Attilio , Galli Remo , Scaglioni Leonardo
Published: November 2006

A series of 1‐(3‐pyridyl)‐1‐substituted‐but‐3‐yn‐1‐ols and some related compounds were synthesised and tested for antifungal activity against eight phytopathogenic fungi of different taxonomic classes. High activity was shown in particular against Sphaerotheca fuliginea on Cucumis sativus. The compounds containing aromatic substituents gave the best results, not only in protectant but also in systemic and eradicant tests. The quantitative structure‐activity relationship suggests that steric effects play an important role in determining fungicidal activity.
Persistence on cotton foliage of insecticide residues toxic to Heliothis larvae
Authors: Wilson Angus G. L. , Desmarchelier James M. , Malafant Kim
Published: November 2006

Control measures for Heliothis spp. on cotton are usually applied against eggs and newly hatched larvae that infest plant terminal growth. In order to investigate the rate of degradation of a range of insecticides, leaf disc samples were collected, at intervals after application, from both fully expanded cotton leaves and unfolding terminal leaves. The samples were subjected separately to bioassay with newly hatched larvae, and to chemical analysis of the surface deposits.

On old leaves, larval mortality caused by two biological insecticides declined by half after field exposure for 36 h, but for the synthetic insecticides, the interval ranged from 4.5 days with endosulfan to 18 days with fenvalerate. On new leaves, the longest interval was 7 days with fenvalerate. Chemical half‐life on old leaves ranged from 1 day with endosulfan to 12 days with DDT, and was also shorter on young leaves than the equivalent biological half‐life. Bioassay appears to be the most reliable method of assessing insecticidal activity over time. Dosage/mortality data were integrated to give LC50 and LC90 values.

Leaf expansion may have the greatest effect on insecticide persistence during the 6 week period of rapid growth commencing 2 months after sowing. Expansion was slower when plants were water stressed, and accelerated following irrigation. The implications of the above findings for cotton pest management are discussed.
The enantiomeric composition of triadimenol produced during metabolism of triadimefon by fungi. Part II: Differences between fungal species
Authors: Deas Adrian H. B. , Clark Terence , Carter Geoffrey A.
Published: November 2006

The fungi Coriolus versicolor, Cladosporium cucumerinum, Botrytis cinerea and Fusarium culmorum, in shake culture, metabolised triadimefon to triadimenol. Analyses by gas–‐liquid chromatography of the triadimenol showed that the fungi produced different qualitative and quantitative combinations of the four possible enantiomers, and that these differences were reproducible. The relationship between the enantiomeric composition of the triadimenol produced and the sensitivity of the test fungi to triadimefon, is discussed in the light of published data on the differences in antifungal activity shown by these enantiomers.
Fluorescence microscope studies of Ustilago maydis and Penicillium italicum after treatment with imazalil or fenpropimorph
Authors: Kerkenaar Antonius , Barug Daniel
Published: November 2006

Imazalil and fenpropimorph caused morphological changes in sporidia of Ustilago maydis and in germinating conidia of Penicillium italicum, as observed by fluorescence microscopy using an optical brightener. Sporidia of U. maydis appeared swollen, distorted, multicellular and, sometimes, branched; conidia of P. italicum swelled in size, and extension of the germ tubes was strongly inhibited. Mycelium of P. italicum, treated with fenpropimorph, showed much enlarged hyphal diameters and relatively short distances between septa. Imazalil and fenpropimorph also caused an irregular deposition of β–1,3 and β‐1,4 polysaccharides, probably chitin, in U. maydis and P. italicum. The latter phenomenon is discussed in relation to the following observed effects of fungicides that inhibit ergosterol biosynthesis: differences in effect on the morphology of budding and filamentous fungi; preferential inhibition of yeast‐hypha conversion in dimorphic fungi; disorganisation of septum formation in budding fungi; and inhibition of spheroplast formation from budding fungi.
Structure‐activity relationships in a group of azoles, with special reference to 1,3‐dioxolan‐2‐ylmethyl derivatives
Authors: Heeres Jan
Published: November 2006

Substituted imidazoles and substituted 1,2,4‐triazoles are active to varying degrees in the control of fungi pathogenic to plants, animals and man. The relationship between chemical structure and their antifungal activity, both in‐vitro and in‐vivo, is reviewed.
Synthesis and fungicidal activity of a series of 1,1‐disubstituted‐but‐3‐yn‐1‐ols
Authors: Arnold Anna , Betto Eliseo , Farina Gandolfina , Formigoni Attilio , Galli Remo , Merlini Lucio
Published: November 2006

Twenty‐three aromatic or heterocyclic 1,1‐disubstituted‐but‐3‐yn‐1‐ols were prepared by the reaction between prop‐2‐ynylmagnesium bromide and suitable ketones. They were tested in vivo for antifungal activity against eight phytopathogenic fungi of different taxonomic classes. Four compounds had noteworthy activity on Sphaerotheca fuliginea in protectant, systemic and eradicant assays. The relationship between structure and activity is discussed on the basis of the recent hypotheses on the mechanism of action of ergosterol biosynthesis inhibitors.