Effect of Adjuvants on the Therapeutic Activity of Dimethomorph in Controlling Vine Downy Mildew. II. Adjuvant Mixtures,Outdoor-Hardened Vines and One-Pack Formulations

Previous investigations have shown that certain C₁₂–C₁₈ alcohol ethoxylates with between 5 and 20 moles ethylene oxide gave large enhancements to the therapeutic activity of emulsifiable concentrate (EC) and wettable power (WP) formulations of dimethomorph in controlling two-day-old infections of downy mildew (Plasmopara viticola, Berl. & deT) on glasshouse propagated vines (Vitis vinifera, L.). In a continuation of that work it has been shown that similar enhancements could also be obtained on vines that had been grown under outdoor conditions for two to three weeks before treatment (outdoor-hardened vines) and it is concluded that the treatments would therefore be effective on field vines. Mixtures of either ammonium sulfate or the silicone ethoxylate, ‘Silwet’ L77, with the best alcohol ethoxylates, ‘Genapol’ C050 or ‘Genapol’ C080, produced slight antagonism of the action of the ‘Genapols’ and therefore were of no benefit. Trials with one-pack formulations prepared containing the ‘Genapol’ adjuvants produced good dose response curves from which estimated doses for 90% fungal control (ED₉₀ values) could be calculated by Logit analysis. These one-pack formulations were significantly more effective than the standard EC formulation (ED₉₀=335 g AI ha⁻¹, glasshouse vines and 445 g AI ha⁻¹, outdoor hardened vines) with optimum enhancements with those formulations containing an adjuvant: dimethomorph ratio of either 9:1 on glasshouse vines (ED₉₀= 13 g AI ha⁻¹) or 6:1 on outdoor-hardened vines (ED₉₀=30 g AI ha⁻¹). This last result was significantly better than that obtained with a commercial formulation of cymoxanil, ‘Fytospore’, (ED₉₀=86 g AI ha⁻¹) and encouraged the recommendation that these one-pack formulations should be examined in field trials.     

Effect of Adjuvants on the Therapeutic Activity of Dimethomorph in Controlling Vine Downy Mildew. I. Survey of Adjuvant Types

The effect of adjuvants on the performance of emulsifiable concentrate (EC) and wettable powder (WP) formulations of dimethomorph, a new systemic Oomycete fungicide, has been investigated using a two-day therapeutic (curative) assay with downy mildew (Plasmopara viticola, Berl. & de T.) on vines (Vitisvinifera L., cv. Cabernet Sauvignon) in glasshouse trials. The EC formulation had some therapeutic activity in this type of test. This activity was increased by the spray tank incorporation of 6 g litre⁻¹ of either emulsifiable rape seed oil (‘Atplus’ 412) or emulsifiable paraffinic oil (‘Atplus’ 411F). However, these improvements in performance were overshadowed by those brought about by incorporation of 3 g litre⁻¹ of a series of C₁₃/C₁₄ alcohol ethoxylates varying in ethylene oxide content from 5 to 20 moles:(‘Marlipal’ 34/6EO, 34/11EO, 34/20EO). Nearly complete fungal control was obtained in the presence of these adjuvants with a dimethomorph application rate of 25 g ha⁻¹ compared with only around 90% control at 400 g ha⁻¹ without adjuvants. The WP formulation was inactive in this therapeutic test but the presence of the adjuvants improved the performance of this formulation towards the high levels observed with the EC plus adjuvants, demonstrating that adjuvants could markedly influence the performance of solid, otherwise therapeutically inactive, dimethomorph formulations. Further trials examined other types of adjuvants (nonylphenol, alkylamine and silicone ethoxylates) but either they were no better than the alcohol ethoxylates or they induced unacceptable phytotoxicity. Trials with alcohol ethoxylates (‘Genapols’) from another source demonstrated activity equivalent to the ‘Marlipal’ surfactants. A two-factorial matrix experiment with ‘Genapol’ C050 showed that, under glasshouse conditions, >90% control could be obtained with the dimethomorph EC at 25 g AI ha⁻¹ with 375 g ha⁻¹ ‘Genapol’ C050. Applications of the WP formulation required slightly higher rates of either 50 g AI ha⁻¹ plus 375 g ha⁻¹ ‘Genapol’ C050 or 25 g AI ha⁻¹ plus 750–1500 g ha⁻¹ ‘Genapol’ C050. The overall conclusion was that alcohol ethoxylates varying in alkyl chain length from C₁₂ to C₁₈ and ethylene oxide content between 5 and 20 moles for the C₁₂ surfactants and ∽15 moles for the C₁₈ surfactants were effective adjuvants in promoting the therapeutic activity of dimethomorph formulationsagainst P. viticola on glasshouse-propagated vines.     

Reinvestigating adjuvants for the wild oat herbicide,flamprop-M-isopropyl. I: Glasshouse trials

Commercial formulations of flamprop-M-isopropyl and formulations of other members of this class of herbicide have always contained an oil adjuvant to increase herbicidal performance. Further increases of performance could be obtained by following the label recommendations to add further quantities of a commercial emulsifiable oil (e.g. ‘Swirl’). Nevertheless it was judged that, in view of current advances in adjuvant research, even greater improvements in herbicidal performance could be obtained with different types of adjuvants. Experimental trials using a cultivated oat (Avena sativa L.) assay under glasshouse conditions to test ranges of surfactants (alkyl aryl, alkyl saccharide, alkylamine and alcohol ethoxylates) and emulsifiable oils (paraffinic/naphthenic, rape seed, transmethylated rape seed) showed that all of these adjuvants were capable of increasing flamprop-M-isopropyl activity compared with that of an emulsifiable concentrate formulation containing no adjuvant. Alkylamine and alcohol ethoxylates, with no particular preference for the length of the alkyl chain, but optimum ethylene oxide content of 5 moles and 7–10 moles respectively, were the most efficacious and better than the current emulsifiable oil system. There was no additional benefit from mixture of these two types of adjuvant and an alcohol ethoxylate (‘Dobanol’ 25-7) was preferred on cost grounds. This adjuvant also gave substantial activity to the otherwise inactive suspension concentrate formulation. Final trials determined that the optimum application rate of ‘Dobanol’ 25–7 was in the range 1000–1500 g ha^?1, and this information guided the design of subsequent field trials.     

Adjuvant Effects on the Therapeutic Control of Potato Late Blight by Dimethomorph Wettable Powder Formulations

Dimethomorph is an effective Oomycete fungicide useful for the control of late blight (Phytophthora infestans, deB) on potatoes (Solanum tuberosum, L.) by preventative (prophylactic) sprays. The results of glasshouse trials using S. tuberosum plants inoculated one day prior to treatment showed that the weak to moderate curative (therapeutic) action of a wettable powder formulation of dimethomorph (WP1) could be substantially enhanced by spray tank adjuvants. A limited survey of surfactant adjuvants indicated that enhancements of performance of WP1 varied with the ethylene oxide content in two series of surfactants, C₁₂/C₁₄ alcohol ethoxylates (‘Genapol’ C series) and nonylphenol ethoxylates (‘Arkopal’ N series). Optimum enhancements were obtained with intermediate degrees of ethoxylation and ‘Genapol’ C080 was adjudged to be marginally superior to its analogues and superior to all of the ‘Arkopal’ series, as well as to a silicone ethoxylate/propoxylate (‘Silwet’ L-77), an alkylamine ethoxylate/propoxylate (‘Armoblen’ 557), and sodium sulfosuccinate (‘Aerosol’ OTB). It was also superior to an emulsifiable paraffinic/naphthenic oil (HVI 60E). Further trials established that relatively high application rates (1000–1500 g ha⁻¹) of ‘Genapol’ C080 were required for maximum enhancement and that the presence of mancozeb, as a co-fungicide, did not substantially affect the enhancement of the therapeutic performance of dimethomorph by ‘Genapol’ C080.     

Effects of adjuvants on the performance of a novel powdery mildew fungicide, 1-(4-chlorobenzyl)-4-phenylpiperidine

The effects of adjuvants on the performance of a dispersible concentrate formulation (DCI) of a novel powdery mildew fungicide, 1-(4-chlorobenzyl)-4-phenylpiperidine (I) were investigated. The method involved assessment, under glasshouse conditions, of the therapeutic (curative) control of infections of powdery mildew (Erysiphe graminis DC f.sp. hordei Marchal) on barley (Hordeum vulgare, L.) eight to nine days after spray application to plants that had been inoculated one day prior to spraying. The results from the first trial showed that marked improvements (∽five-fold) in the performance of DCI could be obtained by the spray tank addition of some types of surfactant adjuvants and a series of further trials investigating a wide range of adjuvants was conducted. Nonylphenol, alkylamine and alcohol ethoxylates varying in mean ethylene oxide content between 5 and 20 moles were highly effective. There were indications that optimum performance enhancements were obtained with these surfactants containing between 5 and 10 moles ethylene oxide. Lower enhancements, sometimes only marginal, were obtained from trisiloxane, phosphate ester, propylene oxide, alkylamine-propylene oxide and castor oil ethoxylates and also alkyl polyglucoside biosurfactants. Negligible adjuvant enhancements were observed with emulsifiable paraffinic/naphthenic and rape seed oils, though slightly better enhancements were seen with an emulsifiable transmethylated rape seed oil and, interestingly, larger enhancements with an emulsifiable lipophilic alcohol. A final trial identified the alcohol ethoxylate, ‘Dobanol’ 91-6, as the most effective adjuvant and that its optimum application rate under glasshouse conditions was 250 g ha^-1. This information will be used to guide the design of field trials. © 1997 SCI     

Effect of adjuvants on the performance of the new cereal fungicide,metconazole. II Field trials

Glasshouse trials had shown that the activity of metconazole formulations against cereal foliar diseases could be enhanced by alcohol ethoxylate adjuvants. A series of soluble liquid (SL) formulations of metconazole had been prepared containing adjuvant: metconazole ratios of 5:1, 7.5:1, 10:1, 15:1 m/m (SL1, SL2, SL3, SL4) which glasshouse trials had shown could give equivalent performance to an emulsifiable concentrate formulation, (ECM) of metconazole at application rates up to three- or four-fold lower than that of ECM alone. A field trials programme was undertaken to compare the performances of these SL formulations with ECM at 120 g AI ha^?1, through a range of application rates (48, 60, 72, 84 g AI ha^?1), in a non-orthogonal factorial trial design against diseases that occurred naturally (Septoria tritici Rob., Puccinia recondita Rob., Pyrenophora teres Drechs., Erysiphe graminis DC) or by artificial inoculation (Leptosphaeria nodorum Muell.), on either Triticum aestivum L. or Hordeum vulgare L. The results from trials in three locations showed that the commercially acceptable performance of ECM at 120 g AI ha^?1, in giving high levels of control of P. recondita, S. tritici and L. nodorum (both prophylactic and therapeutic activity) on T. aestivum. and of E. graminis and P. teres on H. vulgare, could be matched or improved by SL2, SL3 and SL4 at 72 g AI ha^?1. Furthermore, control of E. graminis f. sp. tritici Marchal by these SL formulations at this application rate was better than that by ECM at 120 g AI ha^?1, though the levels of control still remained below commercial acceptability for therapeutic activity. Nevertheless, substantial reductions in the application rate of metconazole have been achieved by using one-pack adjuvant-containing formulations in field trials, while still maintaining excellent control of a range of cereal foliar diseases. The choice between these SL formulations could therefore be made on other grounds such as cost/performance and ease of formulation.     

Effect of the Volume Rate of Application on the Glasshouse Performance of Crop Protection Agent/Adjuvant Combinations

The effects of volume rate of application on the glasshouse performance of three recently developed crop protection agent/adjuvant combinations are discussed. High volume rates of application on easy-to-wet foliage, such as potato (Solanum tuberosum, L.) caused reduction of the adjuvant-enhanced performance of dimethomorph seen at low volume rates. These reductions were largely attributable to relatively lower spray retention with spray drop coalescence and run-off being observed, particularly at the higher adjuvant rates. On difficult-to-wet foliage (wheat, Triticum aestivum, L.; oat, Avena sativa, L.) two different effects were seen. With a metconazole formulation/‘Dobanol’ 91-6 combination on wheat, no systematic changes in performance were observed with change in volume rate. With a flamprop-M-isopropyl formulation/‘Dobanol’ 25-7 combination, statistically significant increases in performance were seen with increasing volume rate. In both cases the observations can be explained as the result of a combination of interacting factors involving spray pattern, spray deposition and, by inference, foliar uptake of the crop protection agent, the proportions of which differed between the two cases. It is suggested that the effect of volume rate of application on performance of adjuvant-containing formulations is investigated on easy-to-wet foliage to determine the upper limits and on difficult-to-wet foliage to determine any variation in performance that may occur. Such information will guide the design of field trials and may aid interpretation of field results.     

Reinvestigating adjuvants for the wild oat herbicide,flamprop-M-isopropyl. II: Field performance

A field trials programme was conducted in which the performance of a new emulsifiable concentrate formulation (ECI) of flamprop-M-isopropyl containing the adjuvant, ‘Dobanol’ 25-7, in a ratio of 2:1 (by weight) with the AI, was compared with the current commercial formulation of ‘Commando’, in combination with its recommended adjuvant, ‘Swirl’, for the control of wild oat (Avena fatua L.) in wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). A further treatment, in which the ‘Dobanol’ 25-7: AI ratio was increased to 4:1 by the spray tank addition of the former, was also included. The mean results from six trials (five wheat, one barley) showed that the addition of ‘Swirl’ to ‘Commando’ was beneficial, increasing wild oat floret control from a mean value of 80% to 92% at current recommended rates (flamprop-M-isopropyl, 600 g ha^?1; ‘Swirl’, 2.5 litre ha^?1). However, combinations of flamprop-M-isopropyl and ‘Dobanol’ 25-7 gave superior levels of control even at lower AI application rates. For example, a mean level of 96% control of Avena spp. was obtained at 300 g AI ha^?1 with 1200 g ha^?1 ‘Dobanol’ 25–7; with even better control at higher rates of application of both components. This improvement in performance was accompanied by a higher risk of crop phytotoxicity than observed with the ‘Commando’/‘Swirl’ mixtures. Symptoms initially were scorch and subsequently growth depression, particularly of tillers. None of the mean values in the six ‘efficacy’ trials reached commercially unacceptable levels, but in a further six ‘crop effects’ trials (three wheat, three barley), in which double rates were applied, the levels of phytotoxicity did become unacceptable and subsequently reduced grain yields. In contrast, two barley ‘crop effects’ trials gave yields higher than the control plots, possibly through the effects of reducing stem length and lodging thereby enabling more efficient harvesting. Nevertheless, there were rates of application of flamprop-M-isopropyl in the range 300–400 g ha^?1 with ratios of ‘Dobanol’ 25-7 in the range 2:1 to 4:1 that would achieve high levels of control of Avena spp. without undue risk of crop phytotoxicity and further trials are planned to support this new adjuvant system.     

Stability of emulsifiable concentrate pesticide formulations in liquid fertilizers

The stability of some diluted emulsifiable concentrate formulations in clear liquid fertilizers, as affected by the nature and concentration of the salt solutions, was checked by a static test. The time-induced changes in the concentration of the dispersed phase were estimated by visual observations and turbidity measurements. For each formulation a specific relationship between the electrical conductivity of all the fertilizer solutions and the emulsion stability was found. This was valid for a pH range between 4.6–6.3; in alkaline conditions the emulsion stability was relatively lower. A critical electrical conductivity range, above which irreversible destabilization occurred, was observed for each formulation: 100-120 dS m^?1 for fenamiphos, 60-70 dS m^?1 for metolachlor, 30-50 dS m^?1 for chlorpyrifos, and about 45 dS m^?1 for S-ethyl dipropylthiocarbamate (EPTC). The correlation observed between the emulsion stability and the electrical conductivity could be used in a simple and rapid qualitative test to estimate the physical compatibility between emulsifiable concentrate formulations and liquid fertilizers.     

Synthesis and bioactivity of some fluorine-containing benzoyl arylureas. Part I: Insecticidal-acaricidal products in which the aryl group bears a trifluoromethyl-substituted alkyl or alkenyl side chain

This paper reports the synthesis and the biological activity of benzoyl arylureas in which the aryl group bears a trifluoromethyl-substitiited alkyl or alkenyl side chain, R. The activity of these compounds has been evaluated on larvae of S. littoralis, A. aegypti, L. decemlineata and on the eggs of T. urticae. In general: (1) the optimum insecticidal activities are achieved when the substituents on the benzoyl moiety, R₁, and R₂, are 2,6-difluoro, the substituents on the aryl moiety, R₃, are 3,5-dichloro and R₁, is 4-(? CH?C(CI)CF₃); (2) the best acaricidal activity is shown when R₁, is 2-CI, R₂, and R₃, are hydrogen atoms and R₁, is 4-(? CH₂CH₂CH(CI)CF₃); (3) the best overall activity is displayed when R₁, is 2-CI, R₂ is hydrogen, R₃ is 3-chloro and R₁ is 4-(? CH₂CH₂CF₃).     

Distribution and activity of spray deposits in an oak canopy following aerial application of diluted and undiluted formulations of Bacillus thuringiensis Berliner against the gypsy moth,Lymantria dispar L. (Lepidoptera: Lymantriidae)

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

Efficacy of new EC formulations of neem oil and pungam oil for the management of sheath rot disease of rice

Neem oil (NO) and pungam oil (PO) based emulsifiable concentrate (EC) formulations,viz., neem oil 60 EC (acetic acid) [NO 60 EC(A)], neem oil 60 EC (citric acid) [NO 60 EC(C] and neem oil + pungam oil 60 EC (citric acid) [NO+PO 60 EC(C)], which had been developed at Tamil Nadu Agricultural University, were evaluated for their efficacy against sheath rot of rice. All three formulations effectively inhibited the mycelial growth of the pathogen,Sarocladium oryzae, underin vitro conditions. There was no significant difference between efficacy of the freshly prepared and stored formulations in arresting the growth ofS. oryzae; efficacy was maintained even after 9 months of storage. These formulations effectively controlled rice sheath rot and led to increased yield in five field trials. Among the various treatments, the formulation NO 60 EC(A) achieved the highest grain yield in four out of five field trials, with a pooled mean grain yield of 4684 kg/havs 3882 kg/ha in the control. NO 60 EC(A) achieved the maximum cost-benefit ratio of 1:4.8, followed by NO+PO 60 EC(C), with 1:3.3.     

液体农药制剂中烷基酚及其聚氧乙烯醚类助剂的高效液相色谱分析

建立了一种测定6类液体农药制剂中烷基酚（alkylphenols,APs）及其聚氧乙烯醚类（alkylphenol ethoxylates,APEOs）助剂的高效液相色谱-荧光分析方法。乳油、水剂、水乳剂、悬浮剂、可溶液剂和微乳剂样品均经甲醇超声辅助提取,稀释后过聚丙烯膜,采用Poroshell 120 EC-C18（4.6 mm×100 mm,2.7 μm）分离,V（甲醇）:V（乙腈）:V（水）=75.5:6.5:18.0三元流动相等度洗脱,荧光检测器检测,外标法定量。结果表明:在0.05~10或0.1~20 mg/L范围内,APs和APEOs的峰面积与其质量浓度间呈良好线性关系（R2均大于0.999 8）;在添加水平范围内（APs:0.5、2、5 mg/g;APEOs:1、5、25、50 mg/g）,6类液体农药剂型中APs和APEOs的平均回收率为73%~110%,相对标准偏差为0.6%~14.9%,方法的定量限在0.5~1 mg/g。该方法简单、快速、准确,适用于不同液体农药制剂中烷基酚及其聚氧乙烯醚类助剂的测定。     

The cross-resistance to pyrethrins and eight synthetic pyrethroids,of an organophosphorus-resistant strain of the rust-red flour beetle Tribolium castaneum (herbst)

Comparisons with standard susceptible insects showed that a strain of Tribolium castaneum, with a specific resistance to malathion and its carboxylic ester analogues, had no cross-resistance to topical applications of natural pyrethrins. Another strain of T. castaneum, showing resistance to many organophosphorus (OP) insecticides, was cross-resistant to pyrethrins ( × 34) and eight synthetic pyrethroids also applied topically; least cross-resistance occurred with resmethrin ( × 2.2), bioresmethrin ( × 3.3) and phenothrin ( × 4.0). Generally larger resistance factors were recorded with formulations synergised by piperonyl butoxide (PB). The greatest cross-resistance encountered was with unsynergised tetramethrin ( × 338). Apart from tetramethrin, factors of synergism did not exceed 5.7 with either the susceptible or multi-OP resistant strains. PB antagonised six of the nine pyrethroids against the multi-OP resistant strain. Antagonism also occurred with two of these six, permethrin (cis: trans ratio 1:3) and 5-prop-2-ynylfurfuryl ( 1RS)-cis,trans-chrysanthemate (‘Prothrin’), against the susceptible strain. Considering only formulations without the synergist, the most effective compounds against the susceptible strain, relative to pyrethrins, were bioresmethrin (2.7) and permethrin (2.4). Similarly with the multi-OP resistant strain the most effective compounds were bioresmethrin (28), resmethrin (14) and permethrin (6.6). Thus the LD₅₀ (the dose required to kill 50% of the test species) for bioresmethrin against the resistant strain (0.14 μg) only slightly exceeded the LD₅₀ for pyrethrins against the susceptible strain (0.12 μg).     

The influence of benomyl formulation on the response of cucumber seedlings (Cucumis sativus) to dibutylurea

Experiments were conducted in a glasshouse to evaluate the phytotoxicity of dibutylurea (DBU), a breakdown product of benomyl, benomyl formulations and constitutive ingredients of ‘Benlate’ Dry Flowable (DF) on whole cucumber (Cucumis sativus. Poinsett 76) plants. Benlate Wettable Powder (WP) and DF formulations did not affect the phytotoxicity of DBU. When commercially purchased (samples obtained from growers) DF and WP formulations containing equivalent DBU concentrations were compared for phytotoxicity, no statistical interactions between formulations were observed. Benomyl, DBU and DF inert ingredients were tested alone and in combination to assess their phytotoxicity. Only DBU at rates greater than 94 mg litre^-1 caused a reduction in root and shoot growth. Also DBU applied alone or as a component of either Benlate formulation was shown to reduce the peak-to-terminal chlorophyll a fluorescence ratio measured in vivo by a plant productivity fluorometer. © 1998 SCI.     

Effect of the fungicide fenitropan on the metabolism of some higher plants and Fusarium oxysporum

The effect of fenitropan [(1RS, 2RS)-2-nitro-1-phenyltrimethylene di(acetate)], a new fungicide from EGYT Pharmacochemical Works, on the photosynthetic activity, respiration, RNA content and protein synthesis of some higher plants and Fusarium oxysporum, was investigated. The effect on the aminoacylation of tRNAs suggests that fenitropan is an inhibitor of the aminoacyl tRNA ligases accepting aromatic amino acids.     

顶空气相色谱法检测农药乳油制剂中甲醇含量

建立了农药乳油制剂中甲醇含量快速检测的顶空气相色谱分析方法。以环己烷为内标,采用DB-1701毛细管色谱柱进行分离,氢火焰粒子化检测器(FID)测定。结果表明,该方法在甲醇体积分数为0.1%～1%范围内线性关系良好,回归方程的相关系数为0.999 1,7次平行测定的相对标准偏差(RSD)小于1.33%,空白溶液甲醇的添加回收率在95%～100%之间。该方法简单实用,可以为其他农药液体制剂中易挥发有毒助剂的检测提供参考。     

Polydisperse ethoxylated fatty alcohol surfactants as accelerators of cuticular penetration. 2: Separation of effects on driving force and mobility and reversibility of surfactant action

Polydisperse ethoxylated fatty alcohol (EFA) surfactants can improve the performance of crop protection agents. At the cuticular level they act as accelerators of penetration by increasing the mobility of active ingredients in the cuticle, the barrier properties of which are mainly caused by cuticular waxes. Polydisperse Genapol C-050 (GP C-050, average formula C12.5E5.8) was also found to increase mobility in wax-extracted polymer matrix membranes (MX) of bitter orange and pear, indicating that sorption of surfactants increased segmental mobility of polymethylene chains in cutin and wax. Sorption into MX of the active fraction of GP C-050 from 5g litre⁻¹ micellar solutions was in equilibrium in less than 1 h after establishing contact. This is almost 100-fold faster than with cuticular membranes (CM). Temperature dependence of solute mobilities in CM was studied in order to measure activation energies (E_D) of diffusion in the presence and absence of aqueous surfactant solutions. Monodisperse fatty alcohol ethoxylates C8E3, C8E4 and C12E6, and (non-surface-active) tributylphosphate decreased E_D of the model compounds WL 110547 and bifenox in Citrus, Pyrus and Stephanotis CM by more than 100 kJ mol⁻¹. This corresponds to 50 to 275-fold increases of mobilities at 15 °C. Our data suggest that the decrease in activation energies with the concomitant accelerating effect on mobility contributes considerably to the effects of so-called activator surfactants. High temperature and accelerators act similarly on barrier properties of CM. It is shown that effects of both monodisperse and polydisperse EFA surfactants on solute mobility are reversible and that radiolabelled C12E8 penetrated pear CM rapidly. However, rates of penetration were lowered by excess amounts of WL 110547 and especially phenylurea. Partition coefficients of seven organic solutes between Capsicum fruit cuticles and GP C-050 were very low and, with the exception of methylglucose, smaller than 1. They decreased with lipophilicity and differed about 100-fold. Especially for the lipophilic compounds they were orders of magnitude lower than octanol/water or cuticle/water partition coefficients, which indicates the limited usefulness of these values for an understanding of penetration of active ingredients from formulation residues. © 1999 Society of Chemical Industry     

Optimisation of a semiochemical slow-release alginate formulation attractive towards Aphidius ervi Haliday parasitoids

BACKGROUND: Optimisation of alginate formulations is described in order to develop semiochemical (E-β-farnesene and E-β-caryophyllene) slow-release devices in biological control approaches by attracting predators and parasitoids of aphids. Various formulation criteria were optimised with respect to semiochemical encapsulation capacity. Moreover, the optimised formulation was characterised by texturometry and confocal microscopy. The slow-release rates of semiochemicals were calculated in laboratory controlled conditions. The attractiveness of semiochemical formulations towards Aphidius ervi was demonstrated by olfactometry. RESULTS: Two major parameters were highlighted in encapsulation optimisation: the type of alginate (Sigma L) and the type of crosslinker ion (Ca²⁺). Other formulation parameters were optimised: ionic strength (0.5 M), Ca²⁺ (0.2 M) and alginate (1.5%) concentrations and the maturation time of beads in CaCl₂ solution (48 h). After physical characterisation of beads, semiochemical slow-release measurements showed that alginate formulations were efficient sesquiterpene releasers, with 503 µg of E-β-farnesene and 1791 µg of E-β-caryophyllene totally released in 35 days. The efficiency of semiochemical alginate beads as attractants for female parasitoids was demonstrated, with high percentages of attraction for semiochemical odours (88 and 90% for E-β-farnesene and E-β-caryophyllene respectively) and significant statistical results. CONCLUSION: Semiochemical alginate beads can be considered as efficient slow-release systems in biological control. These formulations could be very useful to attract aphid parasitoids on crop fields. Copyright © 2011 Society of Chemical Industry     

叶菌唑在小麦中的残留消解及膳食风险评价

为评价叶菌唑在小麦中的残留行为及其产生的膳食摄入风险,于北京、安徽及黑龙江进行了1年3地田间试验,建立了叶菌唑在小麦中的残留分析方法,并对我国不同人群的膳食暴露风险进行了评价。样品用乙腈提取,经Florisil固相萃取柱净化,气相色谱-氮磷检测器(GC-NPD)检测,外标法定量。结果表明:在0.02~10 mg/kg的添加水平下,叶菌唑在小麦籽粒和植株中的平均回收率在81%~101%之间,相对标准偏差(RSD)在2.1%~9.1%之间;其在小麦籽粒和植株中的定量限(LOQ)分别为0.02和0.04 mg/kg。叶菌唑在小麦植株中的消解符合一级动力学方程,半衰期为4.9~7.3 d。收获时小麦籽粒中叶菌唑的最大残留量为0.037 mg/kg,低于美国和欧盟设定的最大残留限量(MRL)0.15 mg/kg。针对我国不同人群的膳食摄入及风险评估暴露,风险商值(RQ)在0.001~0.002之间,表明叶菌唑在小麦中的膳食摄入风险较低。