bluuebunny/crossref_metadata_2025 huggingface dataset:
Spider webs are efficient collectors of agrochemical spray
Authors: Samu Ferenc , Matthews Graham A. , Lake Debra , Vollrath Fritz
Published: November 2006

Spiders are important arthropod predators in natural and agricultural environments. This laboratory study aims to determine the uptake of agrochemical spray by orb webs. Orbs of Araneus diadematus were exposed under controlled conditions to sprays of variable pressure, volume, forward speed and droplet size. Using a tracer dye we determined, by photospectrometry, the amount of spray collected under different conditions which enabled us to calculate the exact volume collected by webs. The spraying treatment simulated four different field practices as well as drift to the field edge. In all cases webs were excellent collectors of spray. Regarding the pure area of the threads, they collected one order of magnitude more of the spray than paper strips did. Moreover, webs were especially efficient in collecting small droplets. We conclude that orb webs (and the spiders who ingest them) are severely exposed to agricultural sprays. Furthermore, due to the uptake of drift, even webs in hedgerows and at field margins may receive high levels of pesticides. The risk of exposing these beneficial arthropods to spray might be reduced by better control of droplet size.
The Affinity Purification of Serum Carboxylesterase from Pigeons Columba livia
Authors: Jackson John B. , Thompson Helen M. , Walker Colin H.
Published: November 2006

Preliminary studies indicate that 3‐butylthio‐1,1,1‐trifluoropropan‐2‐one (BTFP) is a potent, competitive inhibitor of pigeon serum α‐naphthyl acetate esterase (α‐NAE); I50, 9·5 nM.

The synthesis of an affinity resin with 3‐(4‐mercaptobutylthio)‐1,1,1‐trifluoropropan‐2‐one (MBTFP) as the ligand is reported; α‐NAE from serum bound strongly to this. To remove protein from the resin, washing with 3‐octylthio‐1,1,1‐trifluoropropan‐2‐one (OTFP) and subsequent boiling in aqueous sodium dodecylsulfate (SDS) were employed. Recovered protein run on SDS‐PAGE showed a single major protein band at 58–60 kDa which agrees well with previous determinations of the molecular weights of carboxylesterases.
Fate of [14C]Mancozeb in Egg Plants (Solanum melongena L.) during Summer under Sub‐tropical Conditions
Authors: Kumar Uday , Agarwal Hari C.
Published: November 2006

The fungicide mancozeb belongs to ethylenebis(dithiocarbamate) group of fungicides which is used to control brown and black rust, leaf spot, leaf blight, downy mildew etc. on a variety of plants including egg plants, tomato, potato and others. [14C]mancozeb, when applied to the foliage of egg plants (Solanum melongena L.) during summer months, dissipated very rapidly with a half‐life of only 10·6 days. Ethylenethiourea (ETU), ethyleneurea (EU), ethylenethiuram disulfide (ETD), ethylenethiuram monosulfide (ETM) were the metabolites of [14C]mancozeb detected in all the plant parts at different times after the treatment. The amount of ETU in fruits after fourteen days of treatment was only 206 μg kg−1 which is below the maximum permissible level and ultimately came down to 4·6 μg kg−1 after 42 days. EU was found to be the predominant metabolite, suggesting the breakdown of unstable ETU to relatively stable EU under subtropical conditions.
Mobility and persistence of isazofos in granular and microencapsulated formulations in two soils, using field lysimeters
Authors: Bowman Bruce T.
Published: November 2006

Field lysimeters were used to assess the mobility and persistence of microencapsulated and granular formulations of the soil insecticide, isazofos, in Plainfield sand, and the microencapsulated formulation in Vittoria loam soil, using two moisture regimes, rainfall and supplementary watering. Mobility and persistence comparisons were made with an earlier lysimeter study which used emulsifiable concentrate (EC) and granular formulations of isazofos in Plainfield sand. Isazofos mobility in Plainfield sand increased in the following order for the tested formulations: microencapsulated < granular ≦ EC. Atrazine, which was applied as a suspension concentrate to all lysimeters as an internal reference, appeared to exhibit retarded disappearance rates during initial stages of the study when in the presence of granular isazofos in the rainfall treatment. The degradation of isazofos was faster in Vittoria loam than in Plainfield sand for the microencapsulated formulation in the field lysimeters (only formulation tested), and for all three formulations in a laboratory study.
Measured and computed concentrations of 1,3‐dichloropropene in the air around fumigated fields
Authors: Berg Frederik Van Den
Published: November 2006

Concentration patterns of both isomers of 1,3‐dichloropropene in air around two fields were computed with a gaussian plume model for six time intervals after injection of the fumigant into the soil and compared with concentrations measured in the air. During the first three days after the injection of 1,3‐dichloropropene into the soil of one field, the downwind concentrations of 1,3‐dichloropropene in air computed for a height of 1.5 m above the ground ranged up to 19 μg m−3, whereas the downwind concentrations measured ranged up to 29 μg m−3. For the period from five to ten days after injection, the concentrations computed and those measured ranged up to 36 μg m−3 and 16 μg m−3, respectively. For the other field, the computed downwind concentrations in air ranged up to 0.6 μg m−3 during the first three days after injection, whereas those measured ranged up to 23 μg m−3. For the period from four to nine days after injection, the concentrations computed and those measured ranged up to 2.3 and 1.3 μg m−3, respectively. The computations under‐estimated the concentrations in air during the first three days following application, but on later days the computed and measured concentrations were mostly at the same level.
Synthesis and fungicidal activities of CGA 80000 (α‐[N‐(3‐chloro‐2,6‐xylyl)‐2‐methoxyacetamido]‐ν‐butyrolactone) and of its four isomers
Authors: Eckhardt Wolfgang , Francotte Eric , Herzog Jürg , Margot Paul , Rihs Grety , Kunz Walter
Published: November 2006

The preparation of CGA 80000 (α‐[N‐(3‐chloro‐2,6‐xylyl)‐2‐methoxy‐acetamido]‐ν‐butyrolactone) and the separation of the four optical isomers and the diastereomeric pairs of enantiomers are described. The relationships between their absolute configurations and fungicidal activities have been examined. Biological tests have proved that one of the four isomers, with the absolute configuration (aS, 3R) is mainly responsible for the fungicidal activity of CGA 80000.
Conformational analysis of the fungicide fenpropimorph by molecular mechanics calculations and NMR spectroscopy
Authors: Jensen Jette Sandholm , Jørgensen Flemming S. , Klemmensen Per D. , Hacksel Uli , Pettersson Ingrid
Published: November 2006

Fenpropimorph is an inhibitor of Δ8→Δ7‐isomerase and Δ14‐reductase in fungi and cycloeucalenol‐obtusifoliol‐isomerase and Δ8→Δ7‐isomerase in higher plants. A detailed conformational analysis of the most potent enantiomer (S)‐fenpropimorph is described. The conformational analysis is based on three different methods: molecular mechanics calculations. NMR spectroscopy and X‐ray crystallography.

In solution several conformations coexist. The molecular mechanics calculations using MM2(85) show a folded conformation of the unprotonated form of fenpropimorph to be stabilized by at least 3 kcal mol−1 relative to the next lowest energy conformer, suggesting only one conformation of fenpropimorph to be present. A corresponding stabilization of the protonated form (5.4 kcal mol−1) is obtained. However, this stabilization is found partly to be due to attractive steric interactions and may be a phenomenon occurring only in vacuum. In the solid state, fenpropimorph exists in an L‐shaped conformation resembling one of the low‐energy conformers obtained with MM2(85).

Based on comparison with the natural substrate, a totally extended conformation of fenpropimorph is suggested to be the biologically active conformation for interaction with the Δ8 → Δ7‐isomerase in fungi.
Targets for pathology research in protected crops
Authors: Rattink Henk
Published: November 2006

Due to the need to diminish the amount of pesticides used, alternative ways of controlling fungal diseases have to be developed. Foliar diseases have been managed mainly by chemicals, but research has been started to develop integrated control programmes. Data from studies on epidemiology, in combination with nutritional and climatic management and use of partial resistant cultivars will lead to a reduced use of chemicals. Models used are: Botrytis cinerea in gerbera and roses, and powdery mildew in roses and cucumbers. Research has been intensified on biological control of these pathogens. In closed systems, with recirculation of the nutrient solution, soil‐borne fungi can cause serious problems. Not only do diseases known from traditional cultural systems, like fusarium wilt of carnation, fusarium crown and root rot of tomato and Phytophthora and Pythium spp. in several crops occur, but also new problems like a new Phytophthora sp. and Gnomonia sp. in roses and a Cylindrocladium sp. in Spathiphyllum spp. To prevent introduction of pathogens in recirculation systems, emphasis is put on developing an integrated disease management programme by using disease‐free planting material, disease‐free irrigation water, strict hygienic measures, resistant cultivars, methods of disinfecting the nutrient solution and biological control. Research over the last 5–6 years has revealed good prospects for biological control, especially in closed systems with a limited amount of substrate. Wilt in carnation, caused by Fusarium oxysporum f.sp. dianthi can be prevented effectively by adding a non‐pathogenic isolate of F. oxysporum and/or Pseudomonas spp. There are indications that non‐pathogenic isolates of F. oxysporum are also effective against wilt disease in other crops. An isolate of Trichoderma harzianum appears to be very effective against fusarium crown and root rot of tomato. More applications of this, and other, biocontrol agents seem possible. However, translation of the results of research to practical application and registration is still very difficult.
Metabolism of amitrole in apple: II. Bound residues from mature fruits
Authors: Schneider Bernd , Stock Manfred , Schütte Horst R. , Schreiber Klaus , Köster Johannes , Kaußmann Ernst U.
Published: November 2006

Significant radioactivity detected in mature fruits, harvested from apple trees (Malus domestica Borkh., cv. ‘Golden Delicious’ and ‘Gloster’) that were soiltreated with [3,5‐14C]amitrole, remained in the insoluble plant material after exhaustive extraction. These bound residues were solubilized with a mixture of pectinases and cellulases. Thus, separation and characterization of carbohydrates and xenobiotic moieties released during this procedure became possible. A part of the radiolabel was incorporated into natural products, indicating degradation of the applied amitrole and reassimilation of [14C] carbon dioxide.
Biological activity of neem seed kernel extracts and synthetic azadirachtin against larvae of Plutella xylostella L
Authors: Verkerk Robert H. J. , Wright Denis J.
Published: November 2006

The activity of two neem extracts, AZT and NEEM‐AZAL (containing 30 and 3 mg azadirachtin ml−1 respectively) and synthetic azadirachtin (AZ) against second‐instar larvae (L2) of Plutella xylostella L. was examined using leafdip bioassays. On Chinese cabbage, AZ was significantly (P <0.05) less toxic (3 to 4‐fold; LC50 0.54 μg AZ ml−1) than either neem extract against a laboratory strain of P. xylostella (FS). The LC50 values for AZT against the FS and another laboratory strain (Wellcome) were not significantly different on Chinese cabbage. The activity of AZT against the FS and Wellcome strains was similar on Chinese cabbage and Brussels sprout. AZT was significantly less toxic (3‐fold) on Brussels sprout against an acylurea‐resistant field strain (Sawi) when compared with the FS strain on Chinese cabbage. Larval mortality (at day 13) was found to increase with increasing exposure time of P. xylostella (FS) larvae to AZT‐treated Chinese cabbage, although there was little difference in mortality between 48 and 120 h exposure. When AZT, NEEM‐AZAL and AZ were applied at a dose (1 μg AZ ml−1) which gave end‐point mortalities between 50 and 90% (at day 13), all treatments delayed the development of a proportion of surviving larvae but no morphogenetic abnormalities were observed in larvae which reached pupation. Evidence for antifeedant (reduced weight gain) and repellant effects (choicechamber) for AZT were observed with L2 P. xylostella (Wellcome) on Chinese cabbage. AZT was also shown to have ovicidal activity against P. xylostella (Wellcome) at relatively high dose ranges (10‐1000 μg AZ ml−1) as well as some contact activity (FS strain) in topical bioassays. In residual bioassays on glass with adults of the hymenopteran endo‐larval parasitoid of P. xylostella, Diadegma semiclausum (Ichneumonidae), AZT showed little or no activity at rates up to 1000 μg AZ ml−1. In medium‐volume (MV, 200 litre ha−1) and ultra‐low‐volume (c. 1 litre ha−1) spray bioassays on Brussels sprout, AZT gave 16‐92% and 88‐100% mortality respectively (Wellcome strain) at rates approximating to 1‐20 g AZ ha−1. The residual activity of AZT and NEEM‐AZAL against P. xylostella (FS) on Brussels sprout (MV spray) was observed to decrease appreciably after three days, the decline in activity being particularly marked for NEEM‐AZAL.
Bacterial biodegradation of ethoxylated surfactants
Authors: White Graham F.
Published: November 2006

Agricultural, industrial and domestic use of surfactants leads to the entry of these compounds into terrestrial and aquatic ecosystems. Synthetic surfactants vary significantly in structure, but most consist of alkyl or alkylphenol groups attached to nonionic or anionic hydrophilic moieties. Continued use of these compounds is usually justified on the basis that they do not cause pollution problems because they undergo biodegradation by micro‐organisms present in soils and surface waters. In accomplishing biodegradation, micro‐organisms, predominantly bacteria, are exploiting these potentially useful resources of reduced carbon to derive energy and support growth in situations which are otherwise frequently oligotrophic. This paper reviews aspects of surfactant biodegradation, especially in relation to alcohol and alkylphenol ethoxylates used extensively as adjuvants for agrochemicals. In principle, bacteria can employ two strategies to gain access to the aliphatic chains in alcohol ethoxylate surfactants: separation of the hydrophobic chain from the hydrophile (central fission), or direct attack on the ‐terminal of the alkyl chain of the intact surfactant. Direct exo‐cleavage of ethylene glycol units from the polyethylene glycol (PEG) chain also provides a third route to assimilable carbon. In pure cultures of known degraders or in mined environmental samples, all three strategies are exploited, some even within the same organism. Central fission occurs predominantly at the alkyl‐ether bond, but may also occur within the PEG chain itself, thus producing various glycol intermediates which accumulate in pure cultures but appear only transiently in mixed environmental samples. Against this background, the relative resistance of some alkylphenol ethoxylates to biodegradation can be assessed in mechanistic terms. The steric bulk of the aryl nucleus effectively eliminates the central fission pathway. Moreover, some alkyl phenol ethoxylates contain branched alkyl chains which restrict ω‐β‐oxidation. As a result, ethoxylate shortening appears to be the major course of biodegradation observed so far. Not surprisingly, these surfactants are observed to undergo extensive primary biodegradation (removal of surfactant properties) but relatively restricted ultimate degradation to carbon dioxide and normal cell components.
Determination of imidazolidine‐2‐thione (ethylenethiourea) in ethylenebisdithiocarbamate formulations
Authors: Lo Chi‐Chu , Ho Ming‐Hsun
Published: November 2006

Zineb was most seriously contaminated with imidazolidine‐2‐thione (ethylenethiourea; ETU), followed by mancozeb, and maneb. The type of formulation also affects ETU generation and a wettable powder produced ETU more easily than a flowable formulation. The ETU contents of the ethylene‐bisdithiocarbamate (EBDC) mixed fungicides formulations were erratic. Low ETU contents were found in EBDC mixed fungicides, even though some samples had been stored in the laboratory for five years. The cupric ion and the N, O‐containing group of other fungicides might have a stabilizing effect on the degradation of EBDC to ETU. The survey indicated that EBDC mixed formulations could be a useful means of suppressing ETU generation in commercial products.
Comparative excretion of DDT analogues into milk of indian buffalo, Bubalus bubalis L. following oral administration
Authors: Kapoor Sudesh K. , Kalra Rajinder L.
Published: November 2006

Four groups of Indian buffaloes were fed daily with 25 mg of p,p′‐DDT p,p′‐TDE p,p′‐DDE or o,p′‐DDT for 100 days. Milk was analysed for organochlorine residues during this period and also for 100 days after pesticide administration had been discontinued. For the period showing ‘plateau level’ residues, 17.2% of p,p′‐DDE, 17% of p,p′‐TDE, 14% of p,p′‐DDT as p,p′‐DDT (3.5%); p,p′‐TDE (10.5%); 3.2% of p,p′‐DDT as o,p′‐DDT (1.3%) and o,p'‐TDE (1.9%) of their administered amounts were excreted in the milk. Since these compounds were excreted at different rates, the residue levels in the milk expected from a given feed would depend on their concentration and proportional distribution in the feed. The maximum tolerable content of DDT analogues in feed was derived to be 0.1 mg kg−1 (dry weight basis) by using the maximum accumulation coefficient and incorporation of the necessary safety margin. It is concluded that Indian buffaloes fed with rations contaminated with a total of DDT analogues below this limit will yield milk of acceptable quality. Following the termination of feeding with contaminated rations, the elimination of p,p′‐DDE in the milk took the longest time and that of o,p′‐DDT the shortest. These results suggest that the time required for the initial high residue concentration to decline to less than the legal limit would be determined by the relative amounts of DDE, TDE and DDT in the milk, after elimination of the potent source of contamination.
Effect of insecticide—synergist combinations on the survival of Spodoptera exigua
Authors: Van Laecke Kristiaan , Degheele Danny
Published: November 2006

The chitin synthesis inhibitors diflubenzuron and teflubenzuron have recently become ineffective for the control of Spodoptera exigua in floricultural crops. An extended laboratory test with second‐instar larvae of S. exigua on Vicia faba plants was carried out to determine the influence of synergists on the biological activity of three benzoylphenyl ureas (BPUs). The co‐application of piperonyl butoxide, an oxidase inhibitor, did not increase the activity of diflubenzuron, teflubenzuron or hexaflumuron. The best results were obtained with diethyl maleate, for suppressing glutathione S‐transferase activity, and with dimethoate, as a hydrolase inhibitor. A joint application of diflubenzuron (at a concentration which resulted in 43% survival) with diethyl maleate or dimethoate gave only 6.2 and 8.9% surviving larvae, respectively. In addition, development to fourth‐instar larvae was inhibited. The more stable teflubenzuron was synergized by both compounds to a much lesser extent than diflubenzuron. None of the synergists had a significant effect on the activity of hexaflumuron, which was the most potent insecticide of the three BPUs tested against S. exigua.
Simulation of atrazine persistence in Spanish soils
Authors: Obrador Ana , Lechón Yolanda , Tadeo JoséL.
Published: November 2006

The persistence of atrazine was monitored in three fields at different sites in Spain during two consecutive years (1990 and 1991). Laboratory assays for determining the influence of temperature and soil moisture content on the rate of herbicide degradation were carried out on soil samples from the same fields. The degradation constants derived from these assays, together with weather records for the period of the field experiments, were used in a computer program which simulated herbicide persistence in the field. Some adjustments were made to adapt the model to Spanish conditions. The model predicted with reasonable accuracy the persistence of the herbicide in two soils, although there was a tendency to overestimate the residues at early dates. Discrepancies between predicted and measured residues were greater in the third soil, due to rapid initial losses that were not predicted by the program. In this case, the agreement was improved if the program was run taking time zero to be one month after herbicide application. Possible reasons for these discrepancies are discussed.
Purification and herbicide metabolism studies on tulip (Tulipa gesneriana) cytochrome P450
Authors: Topal Ayşegül , Adams Nancy , Dauterman Walter C. , Hodgson Ernest , Kelly Steven L.
Published: November 2006

Microsomal cytochrome P450 from tulip bulbs was solubilized and purified to a specific content of 12.66 nmol mg protein−1. The cytochrome P450 was present as a mixture of two cytochrome P450 polypeptides in approximately equal proportions. Their molecular masses were 52.5 kD and 54.5 kD. Similarities between these proteins included cross‐reactivity with the same antibody. Activity of the purified sample was investigated in a reconstituted enzyme system using the herbicide 2,4‐D (2,4‐dichlorophenoxyacetic acid) as a substrate. A polar product of 2,4‐D was produced which co‐migrated on several chromatography systems with 2,4‐dichlorophenol.
Enhanced biodegradation of γ‐hexachlorocyclohexane (γ‐HCH) in HCH (commercial) acclimatized flooded soil: Factors affecting its development and persistence
Authors: Bhuyan Sasmita , Sreedharan Bindu , Adhya Tapan Kumar , Sethunathan Nambrattil
Published: November 2006

Moist surface soil samples from a flooded soil, pretreated twice with a commercial formulation of an isomeric mixture of hexachlorocyclohexane (commercial HCH) to induce accelerated aerobic biodegradation of γ‐HCH, were incubated at 20, 25 and 35°C with and without replenishment of water lost by evaporation. Soil samples, kept continuously moist, retained the capacity for accelerated aerobic biodegradation of added γ‐HCH even after 40 days incubation at all three temperatures, but the enhancement factor (causing accelerated degradation of γ‐HCH) was inactivated at 25 and 35°C, and not at 20°C, within 20 days when commercial HCH‐acclimatized soil samples were subjected to moisture stress. Evidence suggested that temperature‐induced moisture stress caused the inactivation of the enhancement factor, especially at 35°C. The enhancement factor developed almost with equal ease in both rice‐straw‐amended and unamended soil irrespective of water regime (flooded or non‐flooded) after multiple applications of a commercial formulation of HCH. The population of γ‐HCH‐degrading aerobic, but not anaerobic, micro‐organisms increased distinctly after each successive application of commercial HCH, interestingly at identical rates in both flooded and non‐flooded soils.Sphingomonas paucimobilis isolatedfrom flooded soil degraded α‐,β‐,δ‐ and γ‐isomers of HCH under aerobic conditions.
Progress and developments in adjuvant use since 1989 in the usa
Authors: Foy Chester L.
Published: November 2006

Over 50 articles on adjuvants have been published in Weed Science and Weed Technology, journals of the Weed Science Society of America (WSSA), from July 1989 through September 1992. More than 30 presentations on adjuvants were made at the 1990, '91 and '92 Annual Meetings of WSSA. Research involved c. 45 herbicides, 31 weed species, 19 crops, and numerous adjuvants. Results obtained indicated that the adjuvants tested either enhanced or had no effect on herbicide efficacy. Efficacy was enhanced in the majority of the studies. Some herbicides at lower rates plus adjuvants provided weed control equal to that achieved with higher rates of the same herbicides. Absorption, penetration, and translocation of several herbicides were enhanced with adjuvants. Some adjuvants also enhanced rates of herbicide photolysis, decreased antagonism, prevented herbicide injury to crops, altered the pH of spray solutions, increased deposition and enhanced retention of herbicides, increased rainfastness, promoted better germination of mycoherbicide spores, and were effective formulating agents. Adjuvants appeared to have no effect on herbicides in soil. Product labels of 19 agrochemical companies, involving c. 485 formulations of crop protection chemicals for use in 1992, recommend use of adjuvants with 49% of such formulations; 5% specify that no additional adjuvants are recommended, while the remaining 46% (including granular formulations) do not mention adjuvant use. Adjuvants are recommended with 71% (and not recommended with only 3%) of herbicide (including defoliant) formulations, and recommended with c. 30% and not recommended with c. 14% of the other classes of crop protection chemicals including plant growth regulators, insecticides, miticides, nematicides, fungicides, larvacides, seed treatments, soil fumigants, and repellents. More than 30 types of adjuvant are mentioned on product labels. Several new adjuvants for use with agrochemicals were marketed during 1990–92.
Adjuvants for use with foliar fungicides
Authors: Steurbaut Walter
Published: November 2006

Adjuvants for use with fungicides have been known since the first studies on formulation efficiency and it is now well known that the activity of systemic fungicides can be improved by a proper choice of additives and/or adjuvants. Several studies have clearly demonstrated that these improvements result from changes in such factors as droplet formation, surface contact and behaviour of the deposit, penetration into the leaf (transcuticular or stomatal) and transport within the plant, as well as interactions within the fungal cell.

The transfer of these results from laboratory studies to field trials often yields inconsistent results and simulation models often fail to predict the behaviour of adjuvants under field conditions. This is probably because many factors are involved which cannot be controlled in the field. For example, droplet formation can be very different, leaf structure and canopy formation can interfere, and results for one particular fungicide/crop/fungus/adjuvant combination cannot be translated to another situation. This multiplicity of very complex interactions is probably the main reason why there has been no general breakthrough in practical adjuvant use with fungicides. More applied research is needed to optimise the specific application conditions for each crop/fungicide/fungus combination.

There are still some unresolved problems associated with the use of adjuvants such as loss of selectivity and the occurrence of phytotoxic side‐effects. Also some unexpected specific interactions between adjuvants and formulation constituents can influence the activity which necessitate more fundamental studies on the biochemical and physicochemical background of their mode of action.
Pesticide application as affected by spray modifiers
Authors: Hall Franklin R. , Chapple Andrew C. , Downer Roger A. , Kirchner Loren M. , Thacker J. Richard M.
Published: November 2006

Spray modifiers are materials which affect the physicochemical characteristics of pesticides and hence can enhance or detract from the eventual biological effect. The purpose of this paper is to discuss the effect that spray modifiers (especially adjuvants) have on the interactions and complexities of the pesticide application process.

Foliar application of Crop Protection Agents (CPAs) includes a complex of inter‐linked events: atomization, transport, impaction, retention, deposit formation, movement on or in the plant, and the final biological result. New regulatory constraints question the benefits of many adjuvants and thus use of spray modifiers will be brought to increasingly higher research interest.

At the Laboratory for Pest Control Application Technology (LPCAT), studies on spray modifiers have addressed the problem of identifying (and understanding) these interactions, many of which can be mathematically modelled. The overall aim of the research discussed is to identify the benefits and costs of using spray modifiers and to better understand the role that they may have in the pest control process.
Possible mechanisms for surfactant‐induced foliar uptake of agrochemicals
Authors: Stock David , Holloway Peter J.
Published: November 2006

In the past many mechanisms of action have been proposed to explain the surfactant‐induced uptake of agrochemicals applied to foliage. These are reviewed briefly and discussed in relation to potential sites of uptake activation, particularly in the light of recent radiochemical work on the foliar uptake behaviour of surfactants on intact plants in the presence or absence of model penetrants and pesticides. The body of evidence available is examined in relation to the many outstanding problems that still exist in understanding the role and use of surfactants as uptake activators in agrochemical formulations.
Antagonism of the foliar uptake of glyphosate into grasses by organosilicone surfactants. Part 2: Effects of surfactant structure and glycerol addition
Authors: Gaskin Robyn E. , Stevens Peter J. G.
Published: November 2006

A systematic investigation into the effects of a range of organosilicone surfactants on the foliar uptake of radiolabelled glyphosate into wheat revealed significant antagonism associated with the chemical structure of these adjuvants. Rates of herbicide uptake were influenced by the ratio of the ethylene oxide (EO) hydrophile to siloxane hydrophobe, the mean EO chain length of the surfactant and the chemical nature of the terminal group on the EO chain. In general, antagonism was reduced, or even eliminated, by increasing the polarity of the organosilicone surfactant molecule. Typically, these surfactants markedly enhanced the initial rate of glyphosate uptake, which then slowed abruptly to reach a maximum within 4 h, in contrast to the approximately linear uptake response of the herbicide alone over 24 h following foliar application. The addition of glycerol further increased the initial rapid rate of glyphosate uptake in the presence of an organosilicone, but had no effect on the subsequent slowing down of foliar uptake. These findings are discussed in relation to the possible mechanisms by which these surfactants affect the cuticular penetration of glyphosate.
Adhesion of spray droplets to foliage: The role of dynamic surface tension and advantages of organosilicone surfactants
Authors: Stevens Peter J. G. , Kimberley Mark O. , Murphy Dennis S. , Policello George A.
Published: November 2006

Measurements of the dynamic surface tension of seven surfactants (four organosilicones, two ‚conventional’︁ hydrocarbon‐based surfactants and an organosilicone + hydrocarbon‐based blend; 0.5 to 5.0 g litre−1) have been combined with data on the adhesion of their spray droplets to pea leaf. The latter were determined by a method enabling the surface age, and thus surface tension of the droplets at impact, to be calculated. Adhesion was directly related to the dynamic reduction in surface tension (2 to 50 mN m−1) prior to impact. The organosilicone surfactants and the blend reduced surface tension more rapidly and to lower values than did the organic surfactants. Adhesion was also inversely related to droplet size (110 to 880 μm diameter), droplet velocity (0.3 to 2.8 m s−1) and angle of incidence on the leaf (0 to 67.5 degrees). These physical factors were of less importance than surface tension in controlling adhesion. Relative adhesion varied among the surfactants both with their concentration and with surface tension. These findings are discussed with respect to their implications for the possible involvement of surface viscosity in the spray impaction process.
Pyrethroid residues in sediment and water samples from mesocosm and farm pond studies of simulated accidental aquatic exposure
Authors: Hadfield Stephen T. , Sadler Jill K. , Bolygo Elek , Hill Sarah , Hill Ian R.
Published: November 2006

This paper describes the residue analysis of water and hydrosoil samples taken from two separate large‐scale aquatic ecotoxicology trials designed to assess the environmental fate and effects of the pyrethroids lambda‐cyhalothrin and cypermethrin. Comparison of the results demonstrates the high degree of reproducibility of the chemical residue found the day after treatment using experimental mesocosms (lambda‐cyhalothrin) as opposed to an in‐use farm pond (cypermethrin). Both studies showed that pyrethroid residues were rapidly lost from the water column: residues of lambda‐cyhalothrin were less than 2 ng litre−1 following the final application of a cumulative seasonal exposure equivalent to twelve ‚drift’︁ and six ‚run‐off’︁ events, each delivering a dose equivalent to that expected from a typical event under field conditions. Hydrosoil appeared to act as a sink for pyrethroid residues and, under the stringent test conditions of the mesocosm study, lambda‐cyhalothrin residues reached 3.2 μg kg−1 following the seasonal exposure described above. The cypermethrin farm‐pond study illustrated the localised pattern of exposure expected under natural field conditions, with site topography and cultivation practices which represent an average ‚worst case’︁. Residues in hydrosoil reached a maximum level of approximately 25 μg kg−1 in one sampling zone at one interval, and thereafter declined to a level of < 9 μg kg−1 within four months.
The influence of variable precipitation patterns on simulations of pesticide mobility
Authors: Roth Georg , Stahl Georg , Iwan Jörg
Published: November 2006

The behaviour of pesticides in the soil is governed by a variety of complex processes including the climatic conditions. To investigate the influence of these specific factors, a Monte‐Carlo Method was used to generate sequences of daily precipitation and temperature data representing natural weather behaviour. Simulations of the leaching process were performed for different compounds with these sequences while all other environmental parameters were held constant. The results indicated that the use of stochastic variables yields new insight into the leaching process. It is shown that the naturally occurring variability of the weather pattern has a crucial influence on the leaching of pesticides.
Antifungal activity of flavonoids and their mixtures against different fungi occurring on grain
Authors: Örner Martin Weidenb , Jha Hem Chandra
Published: November 2006

The antifungal activity of three flavones and one flavanone and of different mixtures of these flavonoids was investigated on malt extract agar against four fungi usually occurring on grain. As pure substances the unsubstituted flavone and flavanone showed higher activity than the hydroxylated flavones. Mixtures containing flavone and 7‐hydroxyflavon or flavone, flavanone and flavonol caused higher inhibition of fungal growth than the remaining ones.
The biochemical mode of action of some newer azole fungicides
Authors: Kwok Iris M.‐Y. , Loeffler R. Thomas
Published: November 2006

The effects of the newer azole fungicides BAS 480F, flusilazole, and tebuconazole on growth and sterol composition of the plant pathogenic fungi Botrytis cinerea, Pyrenophora teres, Pyricularia oryzae, Rhynchosporium secalis, Ustilago maydis and Erysiphe graminis f.sp. hordei were compared with those of flutriafol and propiconazole. The results indicate that all the compounds are inhibitors of sterol 14α‐demethylase, and rule out any additional modes of action on sterol biosynthesis.
The microimmersion bioassay: A novel method for the topical application of pesticides to spider mites
Authors: Dennehy Timothy J. , Farnham Andrew W. , Denholm Ian
Published: November 2006

A novel and versatile method is described for measuring the contact activity of acaricides against spider mites. The microimmersion (MI) bioassay involves drawing batches of 25 mites into small pipette tips under vacuum, immersing them for 30 s in 35 μ1 of a test solution, and then confining the treated subjects on clean foliage in holding cells. Evaluations of amitraz, bifenthrin, chlorpyrifos and dicofol against susceptible strains of Tetranychus urticae Koch showed the MI bioassay to be equally applicable to formulated and technical acaricides (the latter dissolved in acetone + distilled water; 20 + 80 by volume), and to give LC50 values that corresponded well with those from a conventional residual bioassay. The most important difference between bioassay methods was the consistently greater slope of probit lines from MI tests. Results were not highly sensitive to varying the immersion period between 15 and 60 s, and low control mortality was observed with ethanol or acetone concentrations of up to 500 ml litre−1, and surfactant concentrations of up to 10 g litre−1. The potential of this method for assessing the relative toxicity of both fast‐ and slow‐acting acaricides, screening small quantities of experimental compounds for acaricidal activity, and improving the laboratory procedure for selection and characterization of acaricide resistance is discussed.
Potential of biopesticides in agriculture
Authors: Rodgers Paul B.
Published: November 2006

All living organisms are subject to predation, parasitism or competition from other organisms. The study of these interactions has led to the identification of many potential opportunities for the use of living organisms as biopesticides to protect agricultural crops against insect pests, fungal, bacterial and viral diseases, weeds, nematodes and mollusc pests. A range of biopesticide products (including as active agents bacteria, fungi, nematodes, protozoa, viruses and beneficial insects) are now available commercially for control of insect pests, fungal and bacterial diseases and weeds. However, world biopesticide sales in 1990 were estimated to be $120 million, representing less than 0–5% of the world agrochemical market. Over 90% of biopesticide sales are represented by a single product type, containing Bacillus thuringiensis Berl., for control of insect pests. Nevertheless, biopesticide sales are estimated to be increasing at 10–25% per annum whilst the world agrochemical market is static or even shrinking. There has been a significant renewal of commercial interest in biopesticides as evidenced by the substantial number of alliances forged between major agrochemical companies and biotechnology companies which allow these major companies access to marketing rights to novel biopesticides.

This paper reviews the current commercial status of biopesticides and discusses the technical and commercial constraints which have impeded development of biopesticides in the past. Novel developments in R&D, which may enable some of these constraints to be overcome, are examined by reference to a number of specific examples (some of which arise from the author's own experience in a biotechnology company). The future prospects for biopesticides are discussed in the light of technical advances and commercial and regulatory requirements.
Mutual antagonism between sterol demethylation inhibitors and phosphorothiolate fungicides on Pyricularia oryzae and the implications for their mode of action
Authors: Sugiura Hisao , Hayashi Keisuke , Tanaka Toshinobu , Takenaka Mitsuaki , Uesugi Yasuhiko
Published: November 2006

Joint action between a phosphorothiolate (PTL) fungicide, iprobenfos, and a sterol demethylation inhibitor (DMI), pefurazoate, was tested by crossed paper technique on three types of field isolates of Pyricularia oryzae Cavara that differed in PTL sensitivity and metabolism. Mutual antagonism in anti‐fungal action between iprobenfos and pefurazoate was observed in a wild‐type field isolate of the fungus sensitive to PTL and in an isolate moderately resistant to PTL, but not in a PTL‐resistant isolate lacking the ability to metabolize PTL. Antagonism of the antifungal action of iprobenfos by pefurazoate seemed to be a result of inhibition of activation by cleavage of the P‐S bond of iprobenfos mediated by mixed‐function oxygenase (mfo) activity, while antagonism of the anti‐fungal action of pefurazoate by iprobenfos may be caused by the binding of pefurazoate by large amounts of an iprobenfos‐induced mfo which results in reduced inhibition of ergosterol biosynthesis. In the PTL‐resistant isolate, the mutually antagonistic action was not observed, presumably because the induction of the mfo‐metabolizing iprobenfos was lacking. Similar antagonism was also observed when another PTL, edifenphos, was used instead of iprobenfos, and when other DMIs, propiconazole, prochloraz and hexaconazole were used instead of pefurazoate. The results of the present experiment indicate that DMIs may also bind to and inhibit an inducible type of fungal mfo which metabolizes xenobiotics, and that PTLs may be activated by an mfo prior to their anti‐fungal action.
Cross‐resistance relationships between benzimidazole fungicides and diethofencarb in Botrytis cinerea and their genetical basis in Ustilago maydis
Authors: Ziogas Basil N. , Girgis Sobhy M.
Published: November 2006

After nitrosoguanidine‐ or UV‐mutagenesis, three different benzimidazole‐resistant phenotypes were isolated on media containing benomyl or a mixture of carbendazim and diethofencarb from wild‐type strains of Botrytis cinerea Pers. ex Fr. and Ustilago maydis (D.C.) Corda. Mutants of B. cinerea with moderate (MBr) or low (LBr) resistance to benzimidazoles and high resistance to diethofencarb (Dr) were isolated from the fungicide‐mixture‐containing medium in low frequency (7–1 × 10−8). Only benzimidazole‐resistant strains highly sensitive to diethofencarb (HBrDs) were identified on benomyl‐containing medium at a frequency of 6.6 × 10−6. Fitness‐determining characteristics such as sporulation, germination and germ‐tube elongation, were found to be reduced significantly in the mutants of B. cinerea that were resistant to both benzimidazoles and diethofencarb. However, pathogenicity of a MBrDr mutant strain on cucumber seedlings was equal to that of the wild type and a carbendazim + diethofencarb mixture was found to control grey mould caused by the wild type, but was not effective when the plant cotyledons were infected by the mutant strain.

Three benzimidazole‐resistant phenotypes (HBrDs, HBrDr, MBrDr) were isolated easily in U. maydis from a benomyl‐containing medium. In contrast with B. cinerea, only one‐tenth of the benzimidazole‐resistant strains were sensitive to diethofencarb. Genetic analysis of benzimidazole resistance in U. maydis showed that the three benzimidazole‐resistant phenotypes were due to three allelic mutations in a single gene and one of them was responsible for the negative cross‐resistance between benzimidazoles and diethofencarb.
Chloroaniline peroxidation by soybean peroxidases
Authors: Laurent François M. G.
Published: November 2006

4‐chloroaniline was oxidized by soya cell‐wall peroxidases in the presence of hydrogen peroxide. The main product, an orange compound with a maximal absorbance at 455 nm, was probably 4, 4′‐dichloroazobenzene. The optimum pH of the reaction was 4. Michaelis constants, determined as described by Dalziel, were 21 mM for 4‐chloroaniline and 94 μM for hydrogen peroxide. Syringaldazine was an uncompetitive inhibitor of 4‐chloroaniline peroxidation (Ki =46 μM) and modified the progress of the reaction with the appearance of a lag period. By contrast, 4‐chloroaniline was a non‐competitive inhibitor of syringaldazine peroxidation with a Ki value of 21 mMx at pH 7.5. Therefore, these two inhibiting effects were compatible with the presence of two binding sites for two different hydrogen donors. Both sites were linked by allosteric interactions. The inferences on chloroaniline binding are discussed.
Inhibition of chitinolytic enzymes from Streptomyces griseus (bacteria), Artemia salina (crustacea), and a cell line from Chironomus tentans (insecta) by allosamidin and isoallosamidin
Authors: Spindler Klaus‐Dieter , Spindler‐Barth Margarethe
Published: November 2006

The influence of allosamidin and its diastereoisomer isoallosamidin on chitinase activity from an insect cell line of Chironomus tentans, the crustacean Artemia salina and the bacterium Streptomyces griseus was studied. The rank order of susceptibility of chitinase activity to both inhibitors was found to be: insects »crustaceans« fungi, although isoallosamidin is about 600‐fold (insect) or 400‐fold (crustacea) less active than allosamidin and does not inhibit chitinase from Streptomyces at all. The complete and exclusive inhibition of N‐acetyl‐β‐D‐glucosaminidase by an acetylgluconolactone‐derivative and chitinase activity by allosamidin indicates that both enzymes can be determined separately in crude extracts, (containing both enzymes), with the substrates 4‐methylumbelliferyl‐N‐acetylglucosaminide or 4‐methylumbelliferyl‐chitoriose, respectively.
Dissipation of residues of MCPA and cyanazine in three forage grasses following post‐emergence application as a mixture in the establishment year
Authors: Cessna Allan J. , Darwent A. Lloyd , Moyer James R. , Cole Dan E.
Published: November 2006

The dissipation of MCPA and cyanazine in smooth bromebrass (Bromus inermis Leyss.), Russian wild ryegrass (Elymus junceus Ficsch.) and intermediate wheatgrass (Agropyron intermedium) (Host) Beauv.) grown at three sites in western Canada was monitored for an eight‐week period following post‐emergence application of the herbicides as a mixture at 0.56 + 0.28 kg ha −1. The grasses were in the two‐ to six‐leaf stage at the time of application. MCPA, as its methyl ester, was detected using electrolytic conductivity detection whereas N‐specific alkali‐ionization detection was used for cyanazine. Foliar MCPA residues decreased more rapidly than those of cyanazine. At 56 days after application, MCPA residues were non‐detectable in all three grass species at all sites. Corresponding residues of cyanazine were of the order of the limit of quantification (0.02 mg kg −1 or less.
Synthesis and acaricidal activity of 3‐aryl‐5‐arylmethyl‐1, 3,4‐oxa(thia)diazol‐2(3h)‐ones
Authors: Bettarini Franco , Capuzzi Luigi , La Porta Piero , Massimini Sergio , Meazza Giovanni , Reggiori Franca
Published: November 2006

A series of new 1,3, 4‐oxa(thia)diazol‐2(3H)‐ones were synthesized and tested as acaricides. High activities against eggs of Tetranychus urticae (Koch) were found for derivatives bearing an ortho‐halo‐substituted phenyl group in position 3, and a benzyl group para‐substituted by a branched C3‐C6 alkoxy group in position 5 of the hetero‐ring. The best compounds attained the miticidal potency of clofentezine.
Effect of azadirachtin‐derived decalin (perhydronaphthalene) and dihydrofuranacetal (furo[2, 3‐fo]pyran) fragments on the feeding behaviour of Spodoptera littoralis
Authors: Blaney Wally M. , Simmonds Monique S. J. , Ley Steven V. , Anderson James C. , Smith Stephen C. , Wood Anthony
Published: November 2006

Decalin and dihydrofuranacetal fragments related to those in azadirachtin exhibited antifeedant activity against larvae of the African leaf‐worm Spodoptera littoralis. Boisd. All the decalin fragments tested were methoxy (C11) derivatives of azadirachtin. The most active decalin fragment had a ketone substitution at C7. Overall, the compounds were more active when tested in combinations of one decalin fragment and one dihydrofuranacetal fragment than when tested singly. Although some of these combinations did show significant levels of antifeedant activity, sometimes coupled with a synergistic effect, they were not as active as either azadirachtin or dihydroazadirachtin.