Showing papers in "Pesticide Science in 1978"
TL;DR: The levels of cross-resistance to diflubenzuron as a larvicide are low and the compound can be used effectively in the field against populations that are highly resistant to conventional insecticides.
Abstract: Diflubenzuron, 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea, possesses larvicidal and ovicidal activities. On larvae it acts mainly as a stomach poison, yet it sometimes exhibits important contact activity. Though all instars can be controlled, older instars are generally less susceptible than younger ones. Histological inspections of Leptinotarsa decemlineata larvae revealed that after ending exposure to the compound, distortions in newly deposited cuticular layers decreased gradually. Ovicidal effects resulted from direct contact of diflubenzuron with eggs or from contamination of females by contact or feeding. Electron microscopic observations of embryos of Leptinotarsa decemlineata, contaminated via the female, also showed disturbed cuticule formation, suggesting a similar activity of the compound in larvae and in eggs.
Spraying the eggs of Leucoptera scitella shows the compound to be mainly ovidical at a rate of 100 mg litre−1, whilst with lower concentrations (10 and 1 mg litre−1) the young larval instar will be killed. The levels of cross-resistance to diflubenzuron as a larvicide are low and the compound can be used effectively in the field against populations that are highly resistant to conventional insecticides. Laboratory and field results, based on larvicidal and ovicidal activities of diflubenzuron, are discussed in respect of species belonging to the Diptera, Lepidoptera, Coleoptera, Acarina (Phyllocoptruta oleivora) and Hemiptera (Eurydema oleraceum and Psylla piri).
150 citations
TL;DR: The action of allethrin has been studied in the free-walking cockroach, Periplaneta americana, using implanted electrodes, at 15 and 32°C, following topical application of an LD95 dose.
Abstract: The action of allethrin has been studied in the free-walking cockroach, Periplaneta americana (L) using implanted electrodes, at 15 and 32°C, following topical application of an LD95 dose (that at 32°C being approximately ten times the LD95 at 15°C). At both temperatures there was marked hyperexcitation of the peripheral nervous system. At 32°C there was also hyperexcitation of the central nervous system but central effects at 15°C were probably secondary. Likewise, nerve blockage often did not occur until many hours after paralysis and could thus be a secondary consequence of allethrin poisoning.
73 citations
TL;DR: The dip-test, a simple, rapid and inexpensive bioassay designed to detect resistance and its different levels gave satisfactory results which warrant its use where biochemical detection of resistance is not possible.
Abstract: Examination of the enzyme that determines the level of resistance to organophosphorus insecticides and carbamates in Myzus persicae (Sulz.) and bioassays were used to establish the frequency and resistance levels of resistant aphids on outdoor crops in Britain in 1976. The biochemical tests, staining esterase-4 after electrophoresis and total esterase determination, were more sensitive than bioassays. However the dip-test, a simple, rapid and inexpensive bioassay designed to detect resistance and its different levels gave satisfactory results which warrant its use where biochemical detection of resistance is not possible. Carboxylesterase activities of M. persicae collected in 1976 fell into three groups: low, moderate and high, and these were correlated with differences in tolerance to dimethoate, demeton-S-methyl and pirimicarb. Aphids with low esterase activity were susceptible(S). Those with the moderately active enzyme (R1) had five- to seven-fold resistance to the two organophosphorus insecticides and were marginally resistant (about two-fold) to pirimicarb. The insects with the most active esterase (R2) were strongly resistant to dimethoate (resistance factor, RF × 126) and moderately resistant to demeton-S-methyl (RF × 17) and pirimicarb (RF × 8). Some R1, but no S aphids survived the recommended dose of demeton-S-methyl on field crops probably because they were under the lowest leaves and therefore protected from direct contact with the spray. Laboratory tests demonstrated that these R1 aphids tolerated the residual deposit and systemic dose present in the leaves of the treated potato-plants. This enabled their numbers to recover in treated fields much faster than the susceptible insects which could do so by immigration only when the residual dose in the plant was no longer toxic. R1 aphids were common throughout the country particularly in eastern England where susceptible aphids were rare, but in the Shardlow area of Derbyshire susceptible aphids were in the majority throughout the summer. R2 aphids were found only in samples from the west of Scotland and northern England. The implications of the presence of aphids with different levels of resistance for aphid control are discussed.
67 citations
TL;DR: The half-life of atrazine, calculated from first-order plots, was lowest at low pH and increased as the pH of the reaction mixture increased as discussed by the authors, and the only product identified after hydrolysis in aqueous fulvic acid solution was 2-ethylamino-4-hydroxy-6-isopropylamino 1,3,5-triazine.
Abstract: The hydrolysis of atrazine in aqueous fulvic acid solution followed first-order kinetics with respect to the herbicide concentration. The half-life of atrazine, calculated from first-order plots, was lowest at low pH and increased as the pH of the reaction mixture increased. Increase in fulvic acid concentration resulted in a higher hydrolysis rate constant and a shortened half-life but had no effect on the activation energy. However, the latter increased with increase in pH of the reaction mixture. The only product identified after hydrolysis in fulvic acid solution was 2-ethylamino-4-hydroxy-6-isopropylamino-1,3,5-triazine.
52 citations
TL;DR: In this paper, the insecticidal activities of a series of 3-phenoxybenzyl pyrethroid esters with a cyano substituent at the 2-, 6-, (R)-α-, or (S)-α-position were compared with those of the unsubstituted analogues.
Abstract: The insecticidal activities to Musca domestica L. and Phaedon cochleariae Fab. of a series of 3-phenoxybenzyl pyrethroid esters with a cyano substituent at the 2-, 6-. (R)-α-, or (S)-α-position are compared with those of the unsubstituted analogues. Only an (S)-α-substituent enhances activity; others diminish or almost eliminate it. (RS)-α-mixtures are generally less active than would be predicted from the potencies of their separate constituents.
49 citations
TL;DR: Aldicarb was incubated in seven soils at 15°C and its loss was well described by first-order kinetics as mentioned in this paper, and the rate constants varied between 0.078 day−1 in a peaty sand to 0.35 day− 1 in a clay loam.
Abstract: Aldicarb was incubated in seven soils at 15°C and its loss was well described by first-order kinetics. Rate constants varied between 0.078 day−1 in a peaty sand to 0.35 day−1 in a clay loam. The concentration-time relationships for aldicarb, its sulphoxide and its sulphone were approximated by a computation model which was used to analyse the importance of the various consecutive and simultaneous reactions. It was computed that 91 to 100% of the aldicarb would be oxidised to its sulphoxide.
45 citations
TL;DR: Triadimefon, 1-(4-chlorophenoxy)-3,3-dimethyl-1-( 1,2,4-triazol-1-yl)butanone, applied at low dosage rates to leaves of marrow, apple or barley plants gave effective control of the appropriate powdery mildew fungi as discussed by the authors.
Abstract: Triadimefon, 1-(4-chlorophenoxy)-3,3-dimethyl-1-( 1,2,4-triazol-1-yl)butanone, applied at low dosage rates to leaves of marrow, apple or barley plants gave effective control of the appropriate powdery mildew fungi. The compound appeared to be systemic and to have considerable vapour-phase activity. In marrow plants, up to 56% of triadimefon was metabolised to a mixture of two corresponding diastereoisomeric secondary alcohols. The mixture was identical with that obtained by chemical reduction of triadimefon. This mixture was also a very effective systemic fungicide and active in the vapour-phase. Triadimefon was also reduced when incubated with Aspergillus niger but this was important only in shake culture. In replacement culture experiments, mycelial mats of this fungus converted the compound into a different metabolite, its isopropyl analogue. This may have resulted from participation of triadimefon in the C-4 demethylation processes involved in fungal biosynthesis of ergosterol. Photolysis caused cleavage of the C-1 to triazole bond liberating 1,2,4-triazole, 4-chlorophenol and 4-chlorophenyl methyl carbonate, all of which were non-fungitoxic. The importance of this photolysis in the in-vivo situation is discussed.
45 citations
TL;DR: In this paper, aldicarb sulphoxide was studied in incubation experiments with soil from four plough layers and two deeper layers, and the loss during the 111 days of the experiment could be described by first-order kinetics.
Abstract: The loss of aldicarb sulphoxide was studied in incubation experiments with soil from four plough layers and two deeper layers. The loss during the 111 days of the experiment could be described by first-order kinetics. The half-lives at 15°C ranged from 20 days in a clay loam to 46 days in a peaty sand. The loss of sulphoxide in deeper layers was considerably slower than in the corresponding top layers of a soil profile. In soil from a silty layer at 70–90 cm depth the half-life was about 53 days. In soil from a sand layer at 90–110 cm depth a loss of only about 15% was measured after 111 days of incubation. First-order rate constants for sulphoxide conversion in a clay loam at 6, 15 and 25°C were found to be 0.009, 0.033, and 0.05 day−1 respectively; in a greenhouse soil these rate constants were 0.0052, 0.019 and 0.04 day−1 respectively. The fractions of aldicarb sulphoxide that were oxidised to sulphone at 15°C in soil from plough layers were computed to range from 0.52 to 0.76.
42 citations
TL;DR: The response of susceptible (S), moderatelyresistant (R1) and strongly resistant (R2) peach-potato aphids, Myzus persicae (Sulz.) to organophosphorus, carbamate and pyrethroid insecticides was tested by a leaf-dip bioassay.
Abstract: The response of susceptible (S), moderately resistant (R1) and strongly resistant (R2) peach-potato aphids, Myzus persicae (Sulz.) to organophosphorus, carbamate and pyrethroid insecticides was tested by a leaf-dip bioassay. The aphids were placed on potato leaves (dipped in insecticide solutions 1–2 or 24 h before infestation) and their mortality examined 48 h later. R1 aphids were virtually susceptible to most of the carbamates, demephion and acephate, but were slightly to moderately resistant (2.1–9.4 times) to permethrin, cypermethrin and (S)-α-cyano-3-phenoxybenzyl (1R)-cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate (I), (NRDC 161), to 5,6,7,8-tetrahydro-2-methylquinolin-4-yl dimethylcarbamate (II), (Hoechst 25 682) and demeton-S-methyl. R2 aphids resisted more strongly or very strongly (between 65 and 1280 times) the pyrethroids, demeton-S-methyl (×94), II (×83) and demephion (×9), and were slightly to moderately (2–5 times) resistant to acephate, pirimicarb, ethiofencarb and 2-(dimethylcarbamoyloxyimino)-3-methoxyimino-N,N- dimethylbutyramide (III), (DPX 3853). Both resistant strains were susceptible to nitrilacarb [4,4-dimethyl-5-(methylcarbamoyloxyimino)pentanenitrile] complex (1:1) with zinc chloride (IV), (AC 85 258). The implications of these results in terms of practical aphid control are discussed.
37 citations
TL;DR: In this paper, a chart relating half-life to temperature and relative humidity is presented in a form suitable for field use, and a mechanism is proposed for loss of fenitrothion.
Abstract: Loss of fenitrothion from post-harvest application to wheat, oats, paddy rice and sorghum followed a second-order rate process, with rate of loss being proportional, at a fixed temperature, to the amount of fenitrothion and the activity of water, which was obtained from the equilibrium partial pressure of water vapour. The effect of temperature on loss was of the form of the Arrhenius equation. A chart relating half-life to temperature and relative humidity is presented in a form suitable for field use, and a mechanism is proposed for loss of fenitrothion.
33 citations
TL;DR: To provide an attractant source in traps, pheromones have been incorporated into solid polymers, notably polythene and rubber, whilst for communication disruption, microencapsulation and ‘hollow fibre’ techniques have been developed.
Abstract: Insect pheromones, in particular sex pheromones, are becoming increasingly important in pest management. As they are both expensive to synthesise and biologically very active, efficient means of controlled release are essential if they are to be used effectively and economically in the field. Pheromone-baited traps can be used for monitoring insect pest populations and for this purpose a long-lasting attractant source with release rate closely simulating that of the insect is required. A second approach involves permeation of the atmosphere with attractant or inhibitory components of sex pheromones in order to disrupt communication between the sexes and thus reduce mating and diminish subsequent larval infestations. For this method to be effective is necessary to maintain the pheromone concentration in treatment areas at a suitably high level for several weeks. The two approaches have led to the development of different kinds of dispensing systems. To provide an attractant source in traps, pheromones have been incorporated into solid polymers, notably polythene and rubber, whilst for communication disruption, microencapsulation and ‘hollow fibre’ techniques have been developed. Recent advances are reviewed and future prospects discussed.
TL;DR: In this article, the degradation of the herbicide diclofop-methyl, ( ± )-methyl 2-[4-(2,4-dichloro-phenoxy)phenoxy]propionate, was investigated in two agricultural soils under aerobic and anaerobic conditions.
Abstract: The degradation of the herbicide diclofop-methyl, ( ± )-methyl 2-[4-(2,4-dichloro-phenoxy)phenoxy]propionate, was investigated in two agricultural soils under aerobic and anaerobic conditions. Using two differently labelled forms of [14C]-diclofop-methyl the qualitative as well as the quantitative formation of extractable metabolites was followed for 64 days. The mineralisation of the uniformly labelled aromatic rings was pursued by monitoring the 14CO2 generated for 25 weeks. As a first step of the degradation a very rapid hydrolysis of the ester bond was detected under all conditions. Diclofop, the corresponding substituted propionic acid formed, was extensively degraded under aerobic conditions, the final product being 14CO2. As an intermediate, a compound later identified by GLC/MS to be 4-(2,4-dichlorophenoxy)phenol, was found in the extracts. Furthermore, traces of six other unknown metabolites were detected. Under anaerobic conditions the degradation proceeded to a small extent. At most 3% of the applied radioactivity was accounted for by the degradation product 4-(2,4-dichlorophenoxy)phenol. No other metabolite, including 14CO2, was observed, implying lack of any further degradation.
TL;DR: In this article, Diquat dibromide can be incorporated into the alginate and this is slowly released into the water close to the plants to become more firmly attached to the weeds.
Abstract: Viscous solutions of sodium alginate can be extruded under water in the form of a string which will stick to weeds. The sodium alginate reacts with calcium ions to form an insoluble gel of calcium alginate so that the strings become more firmly attached to the weeds. Diquat dibromide can be incorporated into the alginate and this is slowly released into the water close to the plants. Two experiments are described in which this technique is tested in a fast-flowing river and for localised control in a lake. Diquat dihromide was found to be effective, when formulated with alginate, on Ranunculus spp. in the river and Groenlandia densa in the lake.
TL;DR: The effect of diflubenzuron, an inhibitor of chitin synthetase, on the deposition of both these components is reviewed in this article, where intermediate degrees of stability are found.
Abstract: Cuticle consists of chitin microfibrils embedded in a matrix composed largely of hydrated proteins. The effect of diflubenzuron, an inhibitor of chitin synthetase, on the deposition of both these components is reviewed. The polymerisation reaction is but one step in the pathway leading to chitin microfibrils. Possibly interactions to other steps in the pathway serve to enhance the consequences of the inhibition. Such enhancement could help to explain the abrupt changes in the rate of chitin synthesis that can be observed as diflubenzuron is cleared from epidermal cells. Cuticle proteins differ widely in their ability to form a stable layer when chitin is largely absent. In the most stable regions, diflubenzuron has no effect on the amount or nature of the proteins deposited. In contrast, there are many regions where the deposition of solid cuticle is stopped, presumably because the proteins involved cannot form a coherent layer. Intermediate degrees of stability are found. There is an association between the regions of stability and those of high sclerotisation; though sclerotisation often takes place long after deposition. Even when the protein layer is fairly stable it may not be deposited in a regular manner. This statement is illustrated by electron micrographs of cuticle from the hind tibiae of adult locusts. These micrographs also show that diflubenzuron can affect epidermal cells. In normal cells the plaques are in contact with the newly secreted cuticle; they are still present but this contact is not maintained after treatment with diflubenzuron.
TL;DR: During the early phase of imbibition and before membrane integrity is fully established, solutes leak out of imbIBing seeds, and it is suggested that this period could be used to advantage if it is wished to insert hormones, micronutrients or pesticides into seed cells.
Abstract: In dry seeds membrane phospholipids adopt a quite, different orientation (the hexagonal phase) to that found in the membranes of cells in growing plants (the lamellar phase). As a seed imbibes water early in germination the phospholipids must change from the hexagonal to the lamellar configuration. Biophysical and biological data indicate that this change occurs as the water content reaches 20–30% of fresh weight. During the early phase of imbibition and before membrane integrity is fully established, solutes leak out of imbibing seeds, and it is suggested that this period could be used to advantage if it is wished to insert hormones, micronutrients or pesticides into seed cells.
TL;DR: The accumulation of 14-methyl sterols suggests that triadimenol acts as a potent inhibitor of one of the metabolic steps involved in the demethylation at the 14-position during ergosterol biosynthesis.
Abstract: In Ustilago avenae sporidia, following the first doubling period of about 4 h, triadimenol (2 μg ml−1) affected sporidial multiplication more severely than other growth processes; daughter cells failed to separate from the parent sporidia resulting in chains of interconnected cells. Triadimenol incubated with the fungus for 8 h interfered neither with respiration nor with protein and nucleic acid synthesis but after 6 h the toxicant had induced a higher content of free fatty acids. Triadimenol markedly altered, both quantitatively and qualitatively, the sterols in sporidia of U. avenae. Incorporation of [14C]acetate (in the form of sodium acetate) into lipid fractions for a period of 2 h revealed that the toxicant powerfully inhibited the synthesis of the 4-demethyl sterol fraction (predominantly ergosterol), whilst the 4,4-dimethyl sterol fraction rapidly accumulated. This was confirmed by g.1.c. analysis of the sterols after 6 and 8 h incubation which showed that the amount of ergosterol, the major sterol in untreated sporidia, was diminished while simultaneously 4,4-dimethyl, 4-methyl and 14-methyl sterols increased. The accumulation of 14-methyl sterols suggests that triadimenol acts as a potent inhibitor of one of the metabolic steps involved in the demethylation at the 14-position during ergosterol biosynthesis.
TL;DR: It is suggested that the effects of DDT on the cockroach nervous system could account for the negative temperature coefficient of toxicity ofDDT.
Abstract: Some effects of DDT on the cockroach nervous system have been correlated with poisoning symptoms, using free-walking cockroaches with implanted electrodes. Experiments at 16.5°C and 32°C used LD95 doses and at 25°C, an estimated LD95. DDT had excitant actions on each nerve studied; cercal afferent and efferent neurones, and abdominal interneurones. The effects on the central nervous system became more marked as temperature was reduced, despite the smaller quantity of DDT employed, but the excitant actions on the peripheral nervous system were not quantified. It is suggested that the effects of DDT on the cockroach nervous system could account for the negative temperature coefficient of toxicity of DDT.
TL;DR: In this article, the extraction from several field soils of the four herbicides benzoylprop-ethyl, nitrofen, profluralin, and tri-allate applied at least 6 months previously was compared using six solvent systems.
Abstract: The extraction from several field soils of the four herbicides benzoylprop-ethyl, nitrofen, profluralin, and tri-allate applied at least 6 months previously was compared using six solvent systems. The residues extracted were quantified using gas chromatographic techniques. Similar recoveries were achieved using 30% aqueous acetonitrile or acetonitrile + water + glacial acetic acid mixtures. The presence of the acetic acid was found to increase residues extracted only in the case of tri-allate. Methanol and 10% aqueous acetonitrile were slightly less efficient in recovering residues from the weathered field soils whereas acetone tended to be a poor solvent for the extraction of the chemicals studied.
TL;DR: Under typical commercial conditions the smaller drop- size approximately halved the incidence of apple mildew found when the conventional 180 μm MMD drop-size spray was used; there was no conclusive advantage against red spider mite.
Abstract: A two-season trial of a mist blower-sprayer with improved air-flow characteristics was made to assess the relative efficiency of 120 and 180 μm mass median diameter (MMD) drop-size sprays for the control of apple powdery mildew (Podosphaera leucotricha) and fruit tree red spider mite (Panonychus ulmi Koch) in a hedgerow-type apple orchard. The principal pesticide was binapacryl, applied at two rates for each drop-size. Under typical commercial conditions the smaller drop-size approximately halved the incidence of apple mildew found when the conventional 180 μm MMD drop-size spray was used; there was no conclusive advantage against red spider mite. Unexpectedly large variations occurred in the deposits from the weekly applications and were related to the humidity during spraying.
TL;DR: An effective but simple integrated control system has been evolved over many decades in East Africa, using a combination of cultural, biological and chemical control.
Abstract: Coffee pests have been estimated to cause losses of about 13 % of the world yield but are most serious in Africa, particularly where Arabica coffee is grown. Coffee pests are normally indigenous and except for the berry borer beetle (Hypothenemus hampei Ferrari) there has been little movement between the main production areas. There is a great variety of pests but because the crop is perennial, evergreen and only grown in areas without climatic extremes, pest populations only rarely become intolerable, being held in check for most of the time by parasites, predators and diseases. Routine spIaying of insecticides in coffee plantations is undesirable for these kill parasites and predators and often result in pest outbreaks. An effective but simple integrated control system has been evolved over many decades in East Africa, using a combination of cultural, biological and chemical control. Pest numbers are monitored continuously by growers and insecticides are used as selectively as possible. The system is ideally suited to areas where labour is cheap but technology is expensive.
TL;DR: In this article, residues of halogenated hydrocarbon fumigants occurring in cereals and their products as a result of use for insect control continue to be of concern in technologically advanced as well as developing countries.
Abstract: Residues of halogenated hydrocarbon ‘liquid’ fumigants occurring in cereals and their products as a result of use for insect control continue to be of concern in technologically advanced as well as developing countries. Carbon tetrachloride and ethylene dibromide residues remaining in wheat, maize, barley and sorghum shortly after fumigation, during storage for periods of up to 1 year and after processing have been determined, with the fumigants applied either as liquids or vapours. Amounts of residues occurring in bread made from wheat containing residual fumigants were also measured. Current methods of use of these fumigants are discussed with reference to the results of these experiments and interim recommendations are made for post- treatment handling of cereals.
TL;DR: In this article, it is shown that the partition coefficients for ethylene between air and various plant organs are relatively high and may change in the course of development, and the possible implications of such compartmentation for the control of plant growth and development are discussed.
Abstract: Work is described showing that ethylene does not move about the plant in physiologically significant amounts due to resistance in the longitudinal direction and loss by emanation from the surface of the plant. Nevertheless, changes in ethylene concentration in one part of the plant may influence concentrations in other parts. It is shown that the partition coefficients for ethylene between air and various plant organs are relatively high and may change in the course of development. These results are discussed in relation to compartmentation of ethylene within the plant and the possible implications of such compartmentation for the control of plant growth and development.
TL;DR: In this article, the half-life for degradation of methazole, 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU) and diuron were incubated in soil at 20°C and field capacity soil moisture content.
Abstract: [14C]-Labelled methazole, 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU), 1-(3,4-dichlorophenyl)urea (DCPU), and diuron were incubated in soil at 20°C and field capacity soil moisture content. Decomposition followed first-order kinetics; half-lives for degradation of these four compounds were 2.4, 144, 30 and 108 days respectively. The amount of DCPMU and DCPU that could be extracted decreased with time and the decrease was accompanied by the generation of an equivalent amount of 14CO2. This was not so in the studies with diuron and methazole, however, and the decrease in the concentrations of radioactivity extracted from soil treated with these compounds could not be entirely accounted for as carbon dioxide. It is concluded that the unextractable radiochemical that was present was DCPMU. Methazole appeared to be degraded through DCPMU to 3,4-dichloroaniline (DCA) with the production of only traces of DCPU.
TL;DR: The degradation of methazole and 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU) was affected by soil temperature and moisture content.
Abstract: [14C]-Labelled methazole was incubated in six soils at 25°C and with soil moisture at field capacity. Under these conditions, methazole was unstable, the concentration declined following first-order kinetics with half-life values in the soils ranging from 2.3 to 5.0 days. The main degradation product was 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU) which was more stable than the parent compound. After about 160 days, DCPMU accounted for 30 to 45% of the initial methazole concentration. Degradation of methazole and DCPMU was affected by soil temperature and moisture content. With methazole, half-lives in one soil at field capacity moisture content and temperatures of 25, 15 and 5°C were 3.5, 8.7 and 31.1 days respectively. The half-life at 25°C was increased to 5.0 days at 50% of field capacity and 9.6 days at 25% of field capacity. A proportion of the initial radioactivity added to the soil could not be extracted and this proportion increased with time. After 160 days this unextractable radioactivity accounted for up to 70% of the amount applied.
TL;DR: In this article, the preparation of 3-phenoxybenzyl chrysanthemates and their dihalovinyl analogues substituted with a cyano group at the 2-, 6-, (R)-α-, or (S)-α- positions is described.
Abstract: Preparation of 3-phenoxybenzyl chrysanthemates and their dihalovinyl analogues substituted with a cyano group at the 2-, 6-, (R)-α-, or (S)-α- positions is described. The (R)- and (S)- isomers of α-cyano-3-phenoxybenzyl esters of 2,2-difluoro-, -dichloro-, and -dibromo-vinyl analogues of cis- and trans- chrysanthemic acid are separated chromatographically, as are the separate pairs of enantiomers of fenvalerate, (RS)-α- cyano-3-phenoxybenzyl (RS)-2-(4-chlorophenyl)-3-methylbutyrate. An optically active ester of α-cyano-3-phenoxybenzyl alcohol (obtained using D-oxynitrilase) with 2,2,3,3-tetramethylcyclopropanecarboxylic acid is synthesised.
TL;DR: Although the yield of fruit from most sprayed trees was greater than from controls, the best mildew eradicants did not produce greatest yields in the same year, perhaps indicating adverse effects of treatments on the trees.
Abstract: Of twenty non-ionic surfactant formulations tested in 1974–75 several were successful as eradicants of overwintering apple mildew as were two ionic materials. The incidence of Nectria canker was increased by sprays applied in October but less so by the same materials applied in January or February when phytoxicity measured in terms of fruit yield was also less. PP 222, a non-ionic surfactant introduced in 1975, proved to be an efficient eradicant of mildew in 1976. Although the yield of fruit from most sprayed trees was greater than from controls, the best mildew eradicants did not produce greatest yields in the same year, perhaps indicating adverse effects of treatments on the trees. However, significantly better yields of fruit obtained in the year following the dormant season eradication of primary mildew, suggest long term beneficial effects of these treatments.
TL;DR: Studies on polymer size, concentration and mode of application, either as foliar spray or soil drench, in relation to the induction of resistance to tobacco mosaic virus (TMV) in Nicotiana tabacum cv xanthi-nc by poly(acrylic acid) (PA) are reported.
Abstract: Studies on polymer size, concentration and mode of application, either as foliar spray or soil drench, in relation to the induction of resistance to tobacco mosaic virus (TMV) in Nicotiana tabacum cv xanthi-nc by poly(acrylic acid) (PA) are reported. PA also induced resistance to TMV in N. glutinosa, to pelargonium leaf curl virus in Datura stramonium, to cucumber mosaic virus in Vigna sinensis and to tobacco ring-spot virus in N. tabacum cv White Burley. No TMV was detected in PA-treated tomato cv Virocross 11 days after inoculation; but the susceptible cultivar Craigella became infected. PA treatment had no effect on TMV replication in White Burley tobacco but resistance was induced to Peronospora tabacina, a fungal pathogen of N. tabacum cv xanthi-nc. The potential of PA-induced resistance as a control measure for viruses and fungi is discussed.
TL;DR: The light-induced decomposition of chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile) in benzene and toluene was found to give rise to one and three products respectively as discussed by the authors.
Abstract: The light-induced decomposition of chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile) in benzene and toluene was found to give rise to one and three products respectively. These were shown by gas chromatography-mass spectrometry to be trichlorodicyanobiphenyls and the benzene adduct was fully identified by 13C n.m.r. spectroscopy as 2,4-dicyano-3,5,6-trichlorobiphenyl.
TL;DR: In this paper, the authors investigated the pathway of degradation of diuron to phytotoxic derivatives when diuron was used as a soil-residual herbicide in irrigation canals.
Abstract: Thin-layer and gas-liquid chromatography, ultraviolet analysis and bioassay with Chlorella spp. have been used to investigate the pathway of degradation of diuron to phytotoxic derivatives when diuron was used as a soil-residual herbicide in irrigation canals. Observations suggest that 1-(3,4-dichlorophenyl)-3-methylurea and 1-(3,4-dichlorophenyl)urea make a contribution to total residues equivalent to a maximum of about 40 and 55%, respectively, of diuron concentrations. Application of a phyto-toxicity rating suggests that in this environment, measurement of diuron specifically would underestimate the total phytotoxicity of residues by a maximum of about 7%.
TL;DR: In this paper, the combination of diffusion and partition processes in controlled release formulations is examined in some detail via theoretical consideration of encapsulated material, and the advantages and disadvantages of controlled release are discussed and the relevance of theoretical considerations of this type to commercial objectives is touched upon.
Abstract: Several physicochemical factors which can influence the interactions between pest and pesticide are described. These relate mainly to the pesticides partition, reaction and diffusion processes. The combination of diffusion and partition processes in controlled release formulations is examined in some detail via theoretical consideration of encapsulated material. Extensive control of release can be obtained this way with the release time ranging from minutes to years. The advantages and disadvantages of controlled release are discussed and the relevance of theoretical considerations of this type to commercial objectives is touched upon.