Suspension Concentrate Research Articles

Residues and dietary risk assessment of fluazinam in root mustard after field experiments.

The residue levels of fluazinam in root mustard were investigated by using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique with ultra-performance liquid chromatography tandem mass spectrometry. Samples of leaf and root mustard were analyzed. The recoveries of fluazinam were 85.2-110.8% for leaf mustard with the coefficient of variation of 1.0-7.2%, and 88.8-93.3% for root mustard with the coefficient of variation of 1.9-12.4%. The suspension concentrate formulation of fluazinam was applied on root mustard at 262.5g a.i. ha-1 in accordance with good agricultural practice (GAP), respectively. After the final application, the root mustard samples were collected at 3, 7, and 14days. Fluazinam residues in root mustard were less than 0.01-0.493mgkg-1. The dietary risk of fluazinam was predicted by comparing intake amounts with the toxicological data, namely acceptable daily intake (ADI) and acute reference dose (ARfD). The risk quotient (RQ) was 72.2-74.3%, for ordinary consumers, which showed negligible risk. According to the maximum residue limit (MRL) and dietary risk assessment, it is suggested that the pre-harvest interval (PHI) of 3days; meanwhile, the MRL of 2mgkg-1 was suggested for fluazinam in root mustard, which indicates that the dietary risk of fluazinam 500g L-1 suspension concentrate (SC) with the recommended usage on root mustard is negligible. This study provided basic data on the use and safety of fluazinam in root mustard to help the Chinese government formulate a maximum residue level for fluazinam in root mustard.

Field Efficacy of Fluopyram Suspension Concentrate against Pine Wilt Disease and Its Distribution and Persistence in Pine Tree Tissues

Fluopyram is a novel nematicide compound with systemic activity, and it is a potential chemical agent for controlling pine wilt disease, which is devastating pine trees worldwide. Here, a fluopyram suspension concentrate (SC) was used to determine its efficacy in controlling pine wilt disease, its distribution in pine tree tissues, and its environmental degradation. Fluopyram SC had an evident inhibitory effect on Pestalotiopsis sp. and showed a good preventive effect on pine wilt disease in healthy pine seedlings. In the field application, after spraying onto the canopy of pine trees, fluopyram was absorbed and translocated downward to all parts of the tree via the branches and needles, and its distribution was stable at 30 days post-application (all samples’ mean residual concentration = 1.166 mg/kg). In addition, the maximum concentration of fluopyram residue in soil and water was 1.139 and 0.099 mg/kg, respectively, at 30 days post-application when fluopyram was significantly degraded. The control efficiency of fluopyram SC in the forest reached 90.48% when the formulation was sprayed by agricultural unmanned aerial vehicles. The half-life of fluopyram SC was 346.6 days, with a persistence of 3 years. These results indicate that spraying fluopyram SC could effectively reduce the number of pine trees dying from pine wilt disease.

Modification of sedimentation and bioaccumulation behavior as an efficient strategy to modulate the toxicity of pyraclostrobin to zebrafish (Danio rerio)

The behavior of pesticide particles or droplets might significantly influence their environmental risks. However, studies on the risk of different pesticide formulations in aqueous environments have rarely been reported. In this study, we prepared three types of pyraclostrobin formulations to evaluate their behavior in the aqueous environment and toxicological risks to zebrafish. The results showed that pyraclostrobin emulsifiable concentrate (EC) sank faster in water with increasing hydrophilicity and density of the solvent. The particles also sank faster with increasing particle size and particle density for suspension concentrate (SC) and microcapsules (MCs). Diverse behavior in water results in different temporal and spatial distributions of the active ingredient. EC-EGDA, SC-5 μm, CS-Large and EC-MO sink or float over time, therefore reducing the effective dose suspended in water. Lower toxicological risks of the pesticides were also observed by reducing the enrichment of pyraclostrobin in zebrafish. In addition to the direct toxicity of the active ingredient, the type of pesticide formulations and their specific compositions might also influence the integrated toxicity. The environmental behavior of pesticide formulations should also be considered for their systematic assessment of environmental risks to ensure the scientific application of pesticides in different scenarios.

A fungicide dresser against fungal phyto-pathogens of narrow-leaf lupin

The laboratory and field study of the dresser Delete Pro SC (suspension concentrate) effectiveness against anthracnose agent and other lupin diseases was carried out in Bryansk region in 2019-2021. Seeds, seedlings and sowings of the narrow-leaf lupin of Vityaz variety were the objects for the research. In the laboratory the effectiveness of Delete Pro (piraclostrobine 200 g/l) was tested in three doses of use (0.5; 1.0 and 1.5 l/t). Biological effectiveness was estimated by the number of infected seedlings grown in paper-and- polyethylene rolls compared to the control (without treatment). The dose 1.5 l/t had the high biological effectiveness against anthracnose (99.4 %). The total germination and the number of seeds with strong seedlings made 99.6 % and 90.4 %, respectively. The length of the roots and hypocotyl of the seedlings reliably increased by 9.4 and 10.6 mm, respectively. In the field test the seeds were treated with 1.5 l/t Delete Pro a month before sowing. The effectiveness of the fungicide was compared to the control variant without treatment. The average dresser biological effectiveness against anthracnose seed infection was 94.3 % during tests years. By the stage of brilliant pod the infected pods number decreased to 3.2 compared to 21.1 % in the control. Fusarium infection decreased from 20.1 % in the control to 13.7 % in the variant; risoctonia solari infection decreased from 9.4 % to 3.0 %. The development of Botrytis blight on the pods decreased 2.8 times. The significant true (LSD05 = 0.82) increasing of seed germination made 13.3 % and survival of productive plants by the harvest period increased by 32.4 %. Due to the application of the fungicide dresser Delete Pro SC (1.5 l/ha), the significant seed yield rise was 0.75 t/ha (LSD05 = 0.03); the cost recovery was 5.11 rubles.

Residue levels and dietary risk assessment of fluopimomide, pyraclostrobin and its metabolite BF-500-3 in garlic ecosystems under field conditions.

To evaluate the residue levels of fluopimomide, pyraclostrobin and its metabolite BF-500-3 in garlic ecosystems, supervised garlic field trials with a commercial formulation (pyraclostrobin·fluopimomide 30% suspension concentrate (SC)) were conducted in six regions of China according to the Good Agricultural Practices (GAP). The residues of fluopimomide, pyraclostrobin and BF-500-3 in field samples were determined using a QuEChERS method combined with high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The average recoveries of all target compounds were 76-94% with relative standard deviations (RSDs) of 1.0-14.5% and limits of quantitation (LOQs) of 0.002mg/kg. At the recommended pre-harvest interval (PHI, 10days), the residues of fluopimomide, pyraclostrobin and BF-500-3 were below 0.16, 0.77 and 0.12mg/kg in garlic chive; below 0.027, 0.22 and 0.002mg/kg in garlic scape; and below 0.002, 0.002 and 0.002mg/kg in garlic, respectively. Dietary intake risks were calculated using risk quotients (RQs) based on field residual data, toxicological data and dietary patterns. The chronic dietary risk quotients (RQc) of pyraclostrobin and fluopimomide were 48.42% and 0.36%, respectively. The acute dietary risk quotients (RQa) of pyraclostrobin in garlic were 0.06-0.15%. These results indicated a low dietary risk for consumers. This study could provide scientific guidance for the application of pyraclostrobin and fluopimomide in garlic.

Study on Droplet Impact and Spreading and Deposition Behavior of Harvest Aids on Cotton Leaves.

The deposition and spreading of pesticide droplets on the surface of plants is a severe challenge to precise pesticide application, which directly affects the pesticide utilization rate and efficacy. Cotton harvest aids are widely used in machine-picked cotton but the effect of formulation and concentration on the droplet behavior and defoliation effect of cotton defoliants is not clear. To clarify the influence of formulation and concentration on the droplet behavior of cotton defoliants, four formulations (suspension concentrate (SC), water dispersible granule (WG), oil dispersion (OD), and wettable powder (WP)) of cotton defoliants were used to prepare different concentrations of harvest aid solutions, according to the spraying volume. The physicochemical properties, droplet impact, and spreading and deposition behavior were studied. The results indicated that the four kinds of harvest aids have good physicochemical properties and can be wet and spread on cotton leaves. The surface tension of the high-concentration harvest aid solution (the spraying volume was less than 1.2 L/667 m2) was increased, which increased the contact angle and reduced the adhesion tension, adhesion work, and the spreading area. Once the harvest aid solution systems impacted the cotton leaves, it could spread to the maximum in a short time (10 ms). The field experiment showed that the droplet spectrum of harvest aids changed slightly, the coefficient of variation (CV) did not exceed 50%, and the defoliation rate was better when the spraying volume was 1.5 L/667 m2. The correlation and principal component analysis showed that the spraying volume (concentration) and coverage were negatively correlated with the defoliation rate, while the viscosity, diffusion factor, and spreading rate were positively correlated with the defoliation rate. Overall, the use of appropriate spraying volume application in cotton fields can improve the performance of spray, increase the effective deposition and wetting spread of defoliants on cotton leaves, further reduce the dosage of defoliants, and improve pesticide utilization. These results can provide a theoretical basis for the scientific preparation and spraying of cotton harvest aid solutions.

Field Assessment of Insecticides as Well as Bio-Pesticides to Manage the Tomato Fruit Borer Helicoverpa armigera Hubner

A field experiment was conducted for the management of tomato fruit borer in the winter period of 2021-22 at the Vegetable Research Station of C.S.A. University, Kanpur. The current study assessed the effectiveness of some novel insecticides as well as bio-pesticides on the Azad T-6 cultivar of tomato crop. Our team used chemical insecticides such as Flubendiamide 39.35% S.C. (Suspension concentrate), Chlorantraniliprole 18.5% S.C. and Fipronil 5% S.C. and bio-pesticides viz. Spinosad 45% S.C., Helicoverpa armigera nuclear polyhedrosis virus (HaNPV) 2% A.S. (Aqueous suspension), Bacillus thuringiensis subsp. kurstaki (Bt) 5% W.P. (Wettable powder) and Neemarin 1500 ppm (parts per million) at their suggested quantity. The observations on the number of larvae were recorded from ten arbitrarily tagged plants in each plot treated with insecticides and bio-pesticides. It was recorded that Flubendiamide 39.35% S.C. @ 0.2 ml/lit was found to be the most efficient against the fruit borer larvae trailed by Chlorantraniliprole 18.50% S.C. @ 0.3 ml/lit in decreasing the larval population and displayed maximum percent decrease in fruit infestation over untreated control. Amongst the bio-pesticides, Spinosad 45% S.C. @ 0.2 ml/lit was found to be the maximum effective over untreated control. All the used insecticides and bio-pesticides in the existing field experiment were found to be superior to the control.

Chitosan as an Adjuvant to Enhance the Control Efficacy of Low-Dosage Pyraclostrobin against Powdery Mildew of Rosa roxburghii and Improve Its Photosynthesis, Yield, and Quality.

Powdery mildew is the most serious fungal disease of Rosa roxburghii in Guizhou Province, China. In this study, the control role of chitosan-assisted pyraclostrobin against powdery mildew of R. roxburghii and its influences on the resistance, photosynthesis, yield, quality and amino acids of R. roxburghii were evaluated. The results indicate that the foliar application of 30% pyraclostrobin suspension concentrate (SC) 100 mg L−1 + chitosan 500 mg L−1 displayed a superior control potential against powdery mildew, with a control efficacy of 89.30% and 94.58% after 7 d and 14 d of spraying, respectively, which significantly (p < 0.01) exceeded those of 30% pyraclostrobin SC 150 mg L−1, 30% pyraclostrobin SC 100 mg L−1, and chitosan 500 mg L−1. Simultaneously, their co-application could effectively enhance their effect on the resistance and photosynthesis of R. roxburghii leaves compared to their application alone. Meanwhile, their co-application could also more effectively enhance the yield, quality, and amino acids of R. roxburghii fruits compared to their application alone. This work highlights that chitosan can be applied as an effective adjuvant to promote the efficacy of low-dosage pyraclostrobin against powdery mildew in R. roxburghii and improve its resistance, photosynthesis, yield, quality, and amino acids.

Study of spinetoram nano suspension for environmentally friendly control of Plutella xylostella L. (Lepidoptera: Plutellidae)

Diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae) is the main pest for brassicas and can potentially cause 90% yield losses. Currently the most effective control method is the use of insecticides, with spinetoram Suspension Concentrate (SC) formulation as one of the newest insecticide generations against this pest. However, there are some limitations in current SC formulations, including run-off issues owing to poor wettability, which may cause low efficacy and severe environmental contamination. Nano formulations that involve very small particles of an insecticide active ingredient could be promising candidates to solve this issue. Therefore, this study aims to prepare spinetoram nano suspension formulations using two modifications milling techniques NS1 and NS2, with various sized ZrO2 beads and evaluated their toxicity against 3rd larvae instars of P. xylostella. The PSA and SEM confirmed that NS1 and NS2 produced nano-sized particles pre-milled (2299.44 nm) to smaller than 100 nm. NS1 and NS2 improved the attachment and penetration of spinetoram into the leaf surface as provided a lower contact angle NS1 (56.98°), NS2 (55.82°), SC (80.03°). The LC50 of NS1 and NS2 with the wetting agent test improved the toxicity by 33% (NS1: 0.0061) and 7% (NS2: 0.0085) compared with SC (0.0091). Without the inclusion of the wetting agent, the spinetoram samples were 46% (NS1: 0.0138) and 41% (NS2: 0.0181) more toxic than SC (0.0256). This result was concluded that spinetoram nano suspension formulations can be administered at low doses as indicating their greater safety, and environmental friendliness than basic SC.

A pH‐ and redox‐stimulated responsive hollow mesoporous silica for triggered delivery of fungicides to control downy mildew of Luffa cylindrica

AbstractBACKGROUNDDowny mildew, a devastating disease of cucurbitaceous crops caused by Pseudoperonospora cubensis. Although a variety of fungicides are used to control downy mildew, choosing an effective product can be challenging. Environmental stimulus‐responsive pesticide delivery systems have great potential to improve the effectiveness of disease and pest control and reduce the impact on environmentally beneficial organisms.RESULTSIn this work, a disulfide bond (SS)‐modified and chitosan oligosaccharide (COS)‐capped hollow mesoporous silica (HMS) pesticide delivery system was synthesized using a hard template method for the control of downy mildew in cucurbit crops. The synthesized nanoparticles were loaded with dimethomorph (DMM), denoted as DMM@HMS‐SS‐COS, and the developmental toxicity of these nanoparticles to zebrafish embryos were evaluated. The results showed that the prepared DMM@HMS‐SS‐COS exhibited excellent dual response properties to pH and glutathione (GSH), with an encapsulation rate of up to 24.36%. DMM@HMS‐SS‐COS has good ultraviolet (UV) radiation stability and adhesion properties. Compared with dimethomorph suspension concentrate (SC), DMM@HMS‐SS‐COS was more effective against downy mildew for up to 21 days. Toxicity tests showed that DMM@HMS‐SS‐COS significantly reduced the effect of DMM on the hatching rate and survival rate of zebrafish embryos.CONCLUSIONSThis work not only demonstrates that DMM@HMS‐SS‐COS could be used as a nanodelivery system for intelligent control of downy mildew but also emphasizes the necessity of increasing the acute toxicity of nanoformulations to non‐target organisms in environmental risk assessment. © 2022 Society of Chemical Industry.

An electrostatic self-assembly approach to prepare tebuconazole nanoparticles with improved sustained release and enhanced antifungal activity

Compared with the traditional pesticides, the nanopesticides (NPs) exhibit better sustained release performance, higher utilization efficiency and reduction of environmental pollution. In this study, the antifungal tebuconazole (TEB) loaded nanoparticles (TEB NPs) were prepared by electrostatic self-assembly of the positively charged poly dimethyl diallyl ammonium chloride (PDADMAC) and sulfobutylether-β-cyclodextrin (SCD) inclusion complex (TEB-SCD) with negative charge. The water solubility and thermal stability of TEB were significantly improved after forming the inclusion complex. The blank NPs and TEB NPs were both characterized by particle size, zeta potential, scanning electron microscopy (SEM), sustained release and antifungal activity. The average particle size of the TEB NPs were 411.75 ± 61.65 nm, and the polydispersity index (PDI) showed low values (< 0.3). The TEB NPs were stable for at least 28 days at 25 °C. Compared with pure TEB, TEB NPs showed the sustained release properties. In addition, TEB NPs exhibited better antifungal activity than TEB industrial concentrate (TC, 98%) and commercially available TEB suspension concentrate (SC) with the 96.33 ± 13.52% antifungal rate of fusarium graminearum. The results indicated that the TEB NPs can improve the antifungal activity and reduce environmental pollution.

PEGylated strategy for new polyurethane construction and its effects in improving the dispersion stability of tebuconazole suspension concentrate

Dispersants play an important role in improving the physical stability of the suspension. In this work, four polyurethane dispersants (PUDs) were successfully designed and synthesized by adjusting the dosage of DMPA and terminating with PEG (600, 800, 1000) through prepolymer dispersion method. Subsequently, 430 g/L tebuconazole suspension concentrate (SC) was selected to investigate the effects of different PUDs on the Zeta potential, particle size, suspension rate, viscosity, absorbance ratio and rheological properties. The results showed that the suspension system was the most stable when the dispersant dosage was 4 wt%. And the dispersion stability of tebuconazole SC prepared with PUD8–600 (8 wt% DMPA) is higher than that of prepared with PUD5–600 (5 wt% DMPA). Furthermore, the dispersion stability of tebuconazole SC is also significantly related to the molecular weights of PEG, in which that PEG-800 end-capped dispersant (PUD8–800) displayed best dispersion stability with low viscosity (187 mPa·s) and zeta potential (- 40.6 mV).

Chitosan as an Adjuvant to Improve Isopyrazam Azoxystrobin against Leaf Spot Disease of Kiwifruit and Enhance Its Photosynthesis, Quality, and Amino Acids

Leaf spot disease caused by Lasiodiplodia theobromae is one of the most serious fungal diseases of kiwifruit production. In this work, the co-application of isopyrazam·azoxystrobin and chitosan against leaf spot disease in kiwifruit and its effects on disease resistance, photosynthesis, yield, quality, and amino acids of kiwifruit were investigated. The results show that isopyrazam·azoxystrobin exhibited a superior bioactivity against L. theobromae with an EC50 value of 0.1826 mg kg−1. The foliar application of chitosan could effectively enhance isopyrazam·azoxystrobin against leaf spot disease with a field control efficacy of 86.83% by spraying 29% isopyrazam·azoxystrobin suspension concentrate (SC) 1500 time + chitosan 100-time liquid, which was significantly (p &lt; 0.05) higher than 78.70% of 29% isopyrazam·azoxystrobin SC 1000-time liquid. The co-application of isopyrazam·azoxystrobin and chitosan effectively enhanced soluble protein, resistance enzymes’ activity in kiwifruit leaves, and reduced their malonaldehyde (MDA), as well as reliably improved their photosynthetic characteristics. Simultaneously, their co-application was more effective in promoting growth, quality, and amino acids of kiwifruit fruits compared to isopyrazam·azoxystrobin or chitosan alone. This study highlights that the co-application of isopyrazam·azoxystrobin and chitosan can be used as a green, safe, and efficient approach for controlling leaf spot disease of kiwifruit and reducing the application of chemical fungicides.

Dissipation and Residues of Pyraclostrobin in Rosa roxburghii and Soil under Filed Conditions.

Rosa roxburghii has been widely planted in China. Powdery mildew is the most serious disease of R. roxburghii cultivation. Pyraclostrobin was widely used as a novel fungicide to control powdery mildew of R. roxburghii. To assess the safety of pyraclostrobin for use on R. roxburghii fruits, its residue rapid analysis as well as an investigation on its dissipation behaviors and terminal residues in R. roxburghii and soil under field conditions were carried out. The QuEChERS method was simplified using LC–MS/MS detection and combined with liquid–liquid extraction purification to allow determination of pyraclostrobin levels in R. roxburghii fruits and the soil. The fortified recoveries at 0.1~5.0 mg/kg were 93.48~102.48%, with the relative standard deviation of 0.64~3.21%. The limit of detection of the analytical method was 0.16 and 0.15 µg/kg for R. roxburghii fruit and soil, respectively. The effects of different spray equipment and formulations on the persistence of pyraclostrobin in R. roxburghii were as follows: gaston gasoline piggyback agricultural sprayer (5.38 d) > manual agricultural backpack sprayer (3.37 d) > knapsack multi-function electric sprayer (2.91 d), suspension concentrate (SC) (6.78 d) > wettable powder (WP) (5.64 d) > water dispersible granule (WG) (4.69 d). The degradation of pyraclostrobin followed the first-order kinetics and its half-lives in R. roxburghii and soil were 6.20~7.79 days and 3.86~5.95 days, respectively. The terminal residues of pyraclostrobin in R. roxburghii and soil were 0.169~1.236 mg/kg and 0.105~3.153 mg/kg, respectively. This study provides data for the establishment of the maximum residue limit (MRL) as well as the safe and rational use of pyraclostrobin in R. roxburghii production.

Assessment of Bacillus thuringiensis var. kurstaki (Bt-127) SC formulation as a component of IPM in soybean through farmer's participatory approach

Insect pests are major biotic constraints limiting soybean production and quality. Soybean growers rely heavily on synthetic chemical insecticides to combat insect pests. Increasing concern for environmental awareness about the use of chemical insecticides has sparked interest in eco-friendly pest management alternatives. An experiment was conducted to assess Bt-127 suspension concentrate (SC) formulation as a component of IPM under real farm situation in Hegdoli village of Kotgiri Mandal, Nizamabad District, Telangana during kharif 2017-18. Incidence of semiloopers (Chrysodeixis acuta and Mocis undata) and tobacco caterpillar (Spodoptera litura) was lowered by 99.5% and 92.9% with the first spray of Bt-127 SC formulation while their incidence was lowered by 99.6% and 97.3%, respectively in farmer's practice with spray of emamectin benzoate. After second spray of Bt-127 SC formulation, incidence of S. litura was lowered by 91.3% and found on par with 91.5% lowering from spray of chlorantraniliprole in farmer's practice. Incidence of natural enemies in IPM field after first and second spray was higher at 0.84 and 0.72 per meter row length in comparison to 0.12 and 0.40, respectively in farmer's practice. The IPM module resulted in higher cost-benefit ratio (1: 2.36) as compared with farmer's practice (1: 1.61).

Role of aliphatic alcohol polyoxyethylene ether phosphate in 25 wt% tebuconazole suspension concentrate: Dispersion and wetting

Aliphatic alcohol polyoxyethylene ether phosphate potassium salt (AE n P-K) and polycarboxylic acid sodium salt (SD-816) served as efficient dispersants to prepare 25 wt% tebuconazole suspension concentrate (SC). Comparison of the Zeta potential, particle size, viscosity and suspension ratios of samples using different combinations of surfactants confirms that the suspension stability of solid particles is the result of electrostatic repulsion, spatial resistance and hydration. The thermal stability and thixotropic stability of SC were investigated to ensure the SCs can withstand complex daily environments. Fortunately, the SCs with AE n P-K have good performance in extreme environments. Furthermore, the addition of AEP-K brings excellent wetting and atomization properties to the SC, which can improve the efficiency of pesticide utilization. This manuscript proposes that small-molecule surfactants used in combination with polymeric surfactants have good dispersant and application effects, and recommends the use of inexpensive AE n P-K as a partial replacement for polymeric surfactants in the research of dispersants for SCs systems in the future. Scheme 1. AEnP-K has role of improving stability and wetting ability of SC.

Etoxazole Stability under Thermal Storage and Its Residues on Green Bean Rods by Quechers Method

A Commercial acaricide etoxazole suspension concentrate (SC) formulation 10% under trade name dagrozoom was purchased from the Egyptian local market to study the etoxazole behavior in the field on green bean pods to estimate the pre-harvest period (PHI) and study the stability of etoxazole active ingredient under accelerator thermal storage conditions according to the food and agriculture organization (FAO) under different temperatures 35±2 оC for 90 days, 45±2 oC for 21days, 54±2 oC for 14 days and 72±2 oC for 5 days. Results indicated that suggested PHI for etoxazole according to the maximum residue limits (MRL) for green bean pods was 15 days from treatment and indicated also that etoxazole active ingredient was more stable and was conformity with FAO specifications when stored at 35±2 oC for 90 days, 45±2 oC for 21days and 54±2 oC for 14 days, on the other side the rate of thermal decomposition of etoxazole active ingredient was increased when stored at 72±2 oC for 5 days and became nonconformity with FAO after 3 days of storage.

Dispersion Performance of Polycarboxylate Terpolymers with Different Alkyl Side-Chain Lengths in Pesticide Suspension Concentrate

A versatile dispersant plays a critical role in the suspension stability of pesticide suspension concentrate (SC) systems. Herein, a series of novel acrylate ester-based polycarboxylate terpolymers (PTs) were designed as dispersant for pesticide suspension concentrate and successfully synthesized in aqueous solutions from the copolymerization of α-methacrylic acid, allyl polyoxyethylene ether, and acrylate (methyl acrylate, ethyl acrylate, and n-butyl acrylate). Terpolymers were characterized by FT-IR and 1H-NMR to confirm their structure. The surface activities of PTs were evaluated according to critical micelle concentration (CMC) and the surface tension at CMC (γCMC). PT-3 with the longest alkyl side-chain length displayed the most superior surface activity due to its lowest CMC value compared with that of the other PTs. Additionally, the dispersion properties of PTs as dispersants in a 600 g/L imidacloprid SC were evaluated. Results showed that compared to the other two PTs, PT-3 contributes to the excellent dispersion properties on imidacloprid SC. Meanwhile, the obtained SC system exhibited shear thinning behavior under high-speed shearing showing typical features of pseudo-plastic non-Newtonian fluids, which conforms to the Herschel–Buckley model. Our results revealed that the effect of the alkyl side-chain length of dispersants could be considered the primary modulator of dispersion performance of SCs.

Experimental Study on the Cement-Based Materials Used in Coal Mine Gas Extraction for Hole Sealing.

Gas drainage is an important method to prevent and control gas disasters. Sealing materials have an important impact on the gas drainage effect. To improve the extraction rate, the configuration and related characteristics of sealing materials were studied in this study. It was found that the fluidity increased gradually with the increase of the dosage of the suspension concentrate (SC). The water–cement ratio was directly proportional to the setting time of the slurry. Also, the mixing amount of the special cement was inversely proportional to the setting time of the slurry. The influence of the amount of foaming agent, special cement, and suspending agent on the expansion rate of the slurry was positive, and the influence gradually weakened. When the water–cement ratio of cement-based materials was 0.6, the special cement content percentage was 6, the suspension agent content percentage was 3, the plasticizer content percentage was 0.7, the early strength agent content percentage was 1.2, and the foaming agent content percentage was 0.2, the sealing effect was the best. The research results suggest that the porosity and pore length of the cement-based material are smaller than those of polyurethane, and its sealing property was better. This could further increase the sealing effect of the gas borehole, thereby facilitating gas extraction.

Residual efficacy of deltamethrin applied to foliage against Malaysian Aedes aegypti (L.) and Aedes albopictus (Skuse).

The spraying of insecticide on foliage to provide an insecticidal barrier may serve as part of the vector control measures to combat the increasing threat of Aedes-borne diseases. The effectiveness of insecticide barrier spraying was evaluated by assessing the residual efficacy of deltamethrin sprayed on foliage against Malaysian Ae. aegypti (L.) and Ae. albopictus (Skuse). In this semi-field study, landscape plants grown within the vicinity of the Institute for Medical Research (IMR), Malaysia, were treated with deltamethrin suspension concentrate (SC) with the dosage of 30 mg/m2 and 50 mg/m2 in three rounds of spraying. Deltamethrin residual activity on treated and untreated leaves was investigated using standard WHO cone bioassays. Wild Aedes populations at both deltamethrin-treated and untreated plant clusters were monitored by ovitrap surveillance. Ovitrap monitoring revealed that the mean number of Ae. albopictus larvae at deltamethrin-treated were significantly lower than the mean number of larvae of the same species at the untreated plant cluster. Cone bioassay results showed that the insecticide remained effective for up to 4 weeks (> 80% mortality), but the insecticide residual activity was affected by rainfall. These results suggest that insecticide barrier spraying is a promising tool and may be used along with other mosquito control tools such as indoor residual spray and space spraying to reduce the dengue burden.