Pesticide Solution Research Articles

Effect of water hardness and surfactant on the particle coverage and distribution of plant protection products granules

The paper presents a study done to determine how particles of different plant protection products (fungicides) are distributed onto treated surfaces when their solutions are prepared with water of different hardness and addition of surfactant. A total of fifteen plant protection products were studied, all in the same concentration of 0.3% with four type of solutions: only distilled water, distilled water plus a wetting agent – the organosilicone surfactant – Silwet L-77, very hard tap water (hardness = 196.9 ррm СаСО3, 11 °dH) and very hard tap water plus wetting agent. The observations and images were made via light microscope with magnification 200X and 3MP digital camera. The images were analyzed for a percent distribution, and spreading of particles by ImageJ software. The results showed that the distribution, and coverage of particles onto treated surfaces can be different even at application of similar plant protection products. The variations in the properties were observed when the solutions were made with waters with different hardness and a wetting agent was added to the solutions. Contrary to the common perception that hard water can reduce the effectiveness of pesticides towards pests, according to the distribution and coverage of particles onto treated surfaces, in some cases hard water can even enhance these properties of the pesticide solutions. Keywords: plant protection products, distribution, coverage, wetting agent, water hardness

Surface hydrophobicity mechanism of poultry red mite, Dermanyssus gallinae (Acari: Dermanyssidae), gives novel meaning to chemical control

Surface hydrophobicity of organisms provides biological self-protection. The hydrophobicity of pest surface, acting as a main obstacle for the pest control, can lead to low utilization and high loss of pesticides. Dermanyssus gallinae is a notorious pest in egg-laying hens, whose control primarily depends on acaricide spraying, while its surface hydrophobicity and potential influence on pesticide effectiveness are not clear. In the present study, the contact angle measurements revealed that the surface of D. gallinae was hydrophobic. Analysis using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the surface microstructures of D. gallinae consist of cuticular folds, with a lipid-rich outermost layer of the cuticle. Based on gas chromatography-mass spectrometry (GC-MS) and gas chromatography (GC), it was found that the major compositions of cuticular lipids were fatty acids and n-alkanes. Modifying the chemical compositions and microstructures of the D. gallinae surface resulted in a reduction in surface hydrophobicity and an increase in the permeation of Rhodamine B through the cuticle. This observation suggested that the chemical compositions and microstructures were pivotal in determining surface hydrophobicity, hindering compound penetration into the cuticle. Finally, it was found improving the wettability of pesticide solution by adding surfactants could overcome the surface hydrophobicity and enhance the efficacy of pesticide against the mites. This study sheds light on the surface hydrophobicity mechanism of D. gallinae and provides a novel strategy to improve the efficacy of acaricides against the mites.

Foliar solution hydrophobicity influenced by plant species, product, and concentration

AbstractFoliar application of nutrients and pesticides is a popular practice for plant maintenance and weed control. Understanding how different products and adjuvants interact with the intended plant leaf surface will improve uptake and decrease losses. Various fertilizer, adjuvant, and pesticide solutions were tested to determine solution hydrophobicity on St. Augustinegrass, tall fescue, and white clover. A 1 µL droplet of each solution was placed on the adaxial leaf surface and imaged with a stereomicroscope to determine average solution contact angle. For all solutions groups, plant species had the most consistent effect, with white clover having the highest average contact angle followed by St. Augustinegrass and tall fescue, respectively. All product solutions significantly reduced the average contact angle compared to water. The urea solution resulted in the largest decrease for the fertilizer group at 7.6%. The largest decrease was found with the siloxane nonionic surfactant, which resulted in a decrease of 87.5% compared to water alone. Significant interactions were found between plant species and product solutions, indicating product solutions interact differently dependent upon the leaf surface characteristics. The results suggest that plant leaf surface, product solution and concentration, and their combination should be accounted for to increase wettability of a foliar application and improve product absorption.

Effects of Spray Adjuvants on Droplet Deposition Characteristics in Litchi Trees under UAV Spraying Operations

In the last decade, unmanned aerial vehicles (UAVs) for plant protection have rapidly developed worldwide as a new method for pesticide application, especially in China and other Asian countries. To improve the deposition quality in UAV applications, adding appropriate types of spray adjuvants into pesticide solutions is one of the most effective ways to facilitate droplet deposition and control efficacy. At present, research on spray adjuvants for UAVs are mainly based on droplet drift and laboratory tests. Few studies have been conducted on the physicochemical properties of spray adjuvants and the effects of droplet deposition characteristics. To explore the properties of four different kinds of spray adjuvants (Mai Fei, Bei Datong, G-2801, and Agrospred 910) and the deposition characteristics of spray adjuvants on litchi leaves, an automatic surface tension meter, a contact angle measuring device, an ultraviolet visible spectrophotometer, and a DJI AGRAS T30 plant protection UAV was used to measure the surface tension, contact angle, and droplet deposition characteristics on litchi under UAV spraying operations. The results showed that the addition of spray adjuvants could significantly reduce the surface tension of the solution. The surface tension value of the solution after adding the spray additives was reduced by 53.1–68.9% compared with the control solution. Among them, the Agrospred 910 spray adjuvant had the best effect on reducing the surface tension of the solution. The contact angle of the control solution on the litchi leaves varied from 80.15° to 72.76°. With the increase in time, the contact angle of the spray adjuvant solution gradually decreased, the Agrospred 910 spray adjuvant had the best effect, and the contact angle decreased from 40.44° to 20.23° after the droplets fell on the litchi leaves for 60 s. The adjuvant solutions increased the droplet size, but the uniformity of the droplet size decreased. The Dv0.5 of different spray solutions ranged from 97.3 to 117.8 μm, which belonged to the fine or very fine droplets, and the Dv0.5 of adjuvants solutions were significantly greater than that of the control solution. The RSs of adjuvant solutions were very similar and ranged from 0.92 to 0.96, all of which were significantly greater than the result of the control solution (0.57). Compared with the deposition of the control solution, the Mai Fei, Bei Datong, and G-2801 solutions clearly increased spray deposition, with total depositions of 0.776, 0.705, and 0.721 μL/cm2, which are all greater than the total deposition of the control solution of 0.645 μL/cm2. The addition of tank-mixed adjuvants could effectively increase the uniformity of the spray deposition, and all the average CVs of adjuvant solutions were lower than 96.86%. On the whole, Mai Fei performed best in increasing the spray deposition and promoting penetration, followed by Bei Datong and G-2801. Meanwhile, the test can also provide a reference for improving the utilization rate of UAV pesticide applications.

Chemical-Free Stable and Multifunctional Electro-Based System for Treatment of Pesticides from Aqueous Solution

The usage of pesticides has become a common practice in modern agricultural systems to meet the growing demand for food production. However, the uncontrolled use of such chemicals results in the deterioration of natural ecosystems and living beings. Thus, herein, a hybrid treatment system performing the combined functions of electro- and photo Fenton was designed to treat aqueous pesticide solution. The anode was comprised of metal oxide-based electrode (MOx), whereas the cathode was comprised of N-doped carbon electrode (N-C). Both the electrodes consist of light-responsive photocatalysts, which facilitates the removal of pollutants by generating reactive radical species such as OH• and O2 •-. The application of external anodic bias helps to improve the photocatalytic activity by preventing the recombination of electron-hole pairs. In addition, N-C on the cathode helps to catalyze the reduction of O2 to H2O2, which further reacts with Fe2+ in the system to initiate the Fenton reaction. The hybrid reactor was further optimized to study the underlying mechanisms by varying the experimental conditions such as pH, current density, electrolyte concentration, and external H2O2 concentration.Moreover, scavenging tests were performed using methanol and tertbutyl alcohol to identify the predominant radical species responsible for removing pollutants from the aqueous solution. Also, the reusability test showed that the prepared electrodes were stable for more than three successive cycles, thus offering sustainability. In general, the present study demonstrates the potential of hybrid treatment units for environmental applications and acts as a stepping stone for future endeavors in material synthesis and sustainable treatment solutions.

Tank-Mix Adjuvants Enhance Pesticide Efficacy by Improving Physicochemical Properties and Spraying Characteristics for Application to Cotton with Unmanned Aerial Vehicles.

Tank-mix adjuvants have been used to reduce spray drift and facilitate the efficacy of pesticides applied with unmanned aerial vehicles (UAVs). However, the effects of specific adjuvants on pesticide characteristics and the mechanism of action remain unclear. Herein, we analyzed the effects of three different types of tank-mix adjuvants (plant oil; mineral oil; and mixture of alcohol and ester) on the surface tension (ST), contact angle, wetting, permeation, evaporation, spray performance, and aphid-control effects of two types of pesticides. The mineral oil adjuvant Weichi (WCH) was highly effective in reducing the pesticide solution ST, improving the wetting and penetration ability, increasing droplet size, and promoting droplet deposition. The mixed alcohol and ester adjuvant Quanrun (QR) showed excellent wetting and antievaporation properties and promoted droplet deposition. A plant oil adjuvant (Beidatong) moderately improved wetting and penetration ability and reduced droplet drift. Field tests showed that the control efficiencies (CEs) of two pesticides were increased after the addition of adjuvants, even with 20% reductions in pesticide application. When the UAV was operated at 1.5 m, the CEs of two pesticides were increased from 65.39 and 66.63% to 73.11-76.52% and 77.91-88.31%, respectively. When operated at 2.5 m, the CEs were increased from 51.24 and 68.60% to 65.06-75.70% and 77.57-92.59%, respectively. Especially, the CEs of pesticides with WCH and QR increased obviously. Importantly, neither WCH nor QR inhibited hatching of the critical insect natural enemy ladybird beetle at concentrations used in the field. This study provides a framework for assessment of tank-mix adjuvants in aerial sprays and directly demonstrates the value of specific adjuvants in improving pesticide bioavailability and minimizing associated environmental pollution.

Understanding dilution effects on particle-containing pesticide droplets deposition on rice leaf via developing CFD-VOF-DPM model.

Pesticide dilution is one of the essential aspects of plant protection. However, the effect of dilution on the deposition characteristics of pesticide droplets containing particulate additives on crop leaf surfaces remains unclear and warrants further research. Herein, a validated computational fluid dynamics (CFD)-volume of fluid (VOF)-discrete phase model (DPM) numerical model was developed to analyze the influence of particle content on the deposition behavior of droplets on the leaf surface comparatively, taking into account the particle content of different diluted thifluzamide solutions. Additionally, the study aimed to analyze further the kinetic behavior of pesticide droplets landing on rice leaves across different dilution conditions. Pesticide droplets diluted 100-fold had a lower retraction rate during spreading than particle-free droplets, so the solution is more easily deposited in the leaves. Moreover, the low dilution (high concentration) increased the critical adhesion rate between droplets and rice leaves, inhibiting the bouncing of droplets on the leaf surface, thus promoting their effective deposition on the surface. In addition, low dilution (high concentration) is not conducive to spreading droplets when the impact velocity is high, and it also results in a large amount of pesticide use. The actual application process can be through understanding the dilution factor of the configured pesticide solution, and reasonable adjustment of the nozzle pressure can effectively improve the utilization rate of pesticides and reduce the pollution brought by pesticides to the environment. These results provide an essential reference for studying pesticide droplet deposition characteristics, including rice plant protection and spraying technology. © 2024 Society of Chemical Industry.

A Flexible Terahertz Metamaterial Sensor for Pesticide Sensing and Detection.

Terahertz (THz) waves have garnered significant interest across various fields, particularly in high-sensitivity sensing applications. Metamaterials can be employed in THz sensors, specifically for refractive index sensing and pesticide detection due to their high-sensitivity characteristics. In this Article, a dual-band flexible THz metamaterial sensor based on polyimide is proposed for refractive index and pesticide sensing, which is fabricated using ultraviolet (UV) lithography technology and measured by a THz time-domain spectroscope (TDS) system. The resonant frequencies of the sensor are at 0.37 and 1.13 THz, with transmission rates of 2.9% and 0.3%, respectively. With an analyte layer attached to the sensor's surface, the sensitivity of refractive index sensing can be calculated as 0.09 and 0.28 THz/RIU (refractive index unit) at the two resonant frequencies. In order to validate the exceptional pesticide sensing performance of the sensor, chlorpyrifos-methyl acetone solutions with various concentrations are added on it. Furthermore, a monolayer of graphene is coated on the sensor's surface, which is proved capable of improving pesticide sensing sensitivity at low concentrations due to strong π-π stacking interactions with π-electrons in chlorpyrifos-methyl solutions. Therefore, the graphene-coated sensor can be utilized in detecting pesticide solutions with low concentrations, and the sensor without graphene is preferred for high concentration detection. This work provides a novel option for the THz metamaterial sensor with high sensitivity covering a wide pesticide concentration range.

Impact of direct and indirect ingestion of six systemic pesticides on the parasitoid Anagyrus vladimiri

Anagyrus vladimiri (Hymenoptera: Encyrtidae) is the main parasitoid of Planococcus citri (Hemiptera: Pseudococcidae), which is one of the most important pests of citrus crops in the Mediterranean Basin. Pesticide residue on trees and in the nectar of wildflowers growing in citrus orchards might cause side effects in beneficial insects. In the present study, we assessed the effects of six systemic pesticides (acetamiprid, dimethoate, cyantraniliprole, flupyradifurone, spirotetramat and sulfoxaflor) on the survival and progeny of A. vladimiri. Anagyrus vladimiri fed on the pesticide solutions and on the nectar of Fagopyrum esculentum Moench plants that had been watered with a solution containing these pesticides. Acetamiprid, dimethoate, flupyradifurone and sulfoxaflor increased female mortality more than the control (water) after 6h; after A. vladimiri consumed these pesticides, female mortality ranged from 62% to 73%. Cyantraniliprole had no immediate toxic effect on parasitoid survival but caused mortality after 15 days. All tested pesticides except flupyradifurone and spirotetramat reduced parasitoid progeny. After six days of feeding on F. esculentum nectar of plants watered with a pesticide solution, significantly increased female mortality was observed with dimethoate (96%), spirotetramat (80%), acetamiprid (62%), cyantraniliprole (62%) and sulfoxaflor (50%). Progeny was reduced in females that fed on plants treated with spirotetramat and dimethoate. These results demonstrate that some of these insecticides can have lethal or sublethal effects on A. vladimiri by both routes of exposure, via direct or indirect pesticide consumption through the nectar of treated plants.

Development of a label‐free, impedance‐based biosensor to identify harmful effects of pesticides on insect cells

AbstractInsects are a major part of the planet's ecosystem and their vital role as pollinators for agriculture is undisputed. Alongside factors as climate change or loss of habitats, rising use of pesticides emerges as a key threat to insect populations. For fighting this man‐made problem, development of an easy, fast, sensitive, and non‐invasive biosensor for determining pesticide toxicity may help to ban harmful substances and formulations. Here, a biosensor based on Sf21 (Spodoptera frugiperda) insect cells as sensors and electric cell‐substrate impedance sensing (ECIS) as physical transducer is described. Sf21 cell suspensions and well‐defined pesticide solutions were mixed immediately before seeding on planar gold‐film electrodes. The capacitance at 20 kHz was recorded as a function of time as a measurand for cell adhesion providing dose–response profiles of pesticide impact. For future in‐field applications, decoupling of the cell culture routines from the actual cytotoxicity assay is mandatory. Thus, suspensions of Sf21 cells were cryopreserved at –80°C in the wells of multielectrode arrays and thawed anytime for conducting the assays. Five pesticides were tested for their concentration‐dependent cytotoxicity expressed as EC50 values by ECIS and validated using the well‐established WST‐1 cell viability assay. Results were found to be in good agreement. Our studies revealed cytotoxic effects of some pesticides sold for home usage far below the recommended concentration and were found to be more toxic than formulations sold for agricultural industry only.

Investigation of consciousness levels of Çanakkale farmers on environmental and toxicological risks of pesticides

Pesticides are increasingly being used against pests in agricultural fields. However, unconscious use of pesticides results in health risks for humans and the environment. Efforts should therefore be spent to reduce the negative impacts of pesticides. The objective of this study was to measure farmers’ awareness of pesticide use in the agricultural fields of Çanakkale. The sample size was calculated using the “Simple Random Sampling Based on Means” method. The present survey was conducted with 270 farmers. Of the farmers who participated, 25.55% had 31-40 years of farming experience, 47.78% were primary school graduates, and 35.56% were 55-65 years old. Farmers’ knowledge of pesticide use was assessed through Likert scale. Chi-Square test was used to investigate the relationship of farmers’ knowledge level with education, age, farming experience, land size and farming type. Only education was significant. As the education level increased, the knowledge level increased. In terms of farmers’ attitudes, 78.89% of the farmers indicated that they changed their clothes after spraying, 46.67% cared about the information on pesticide labels, 45.18% used protective equipment during spraying, 69.63% cared about PHI (pre-harvest intervals), and 15.92% had knowledge about MRL (Maximum Residue Limit). 41.85% disposed of remaining pesticide solutions to the edge of agricultural fields, 40.74% to garbage and 6.3% to environment. It was concluded based on the present findings that farmers need serious training on pesticide use and the potential effects of pesticides on human health and the environment.

Co-Metabolism Kinetics of Bioremediation of Lambda Cyhalothrin, Chlorpyrifos and Malathion Contaminated Loam Soil Using Bio-Slurry Microbes

The indiscriminate use of insecticide in agricultural soils causes significant soil and water pollution and poses a serious threat to the global community. Degradation of these pollutants is therefore vital in pollution control. Microbial fuel cells have been employed in bio-remediation of organic pollutants due to its environmental friendliness and low cost. The occurrence of pesticides in soil has become a highly significant environmental problem, which has been increased by the vast use of pesticides worldwide and the absence of remediation technologies that have been tested at full-scale.
 In this study, bioremediation experiments were conducted at ambient temperature of 28-32 0C and pH 5.6-8.9 to investigate the effectiveness of the process in the clean-up of pesticide contaminated loam soils. The loam soil was assessed for macro and micro properties prior to the experiments in control procedures. A H-shaped double chamber microbial fuel cell was fabricated where the anodic chamber was loaded with 750 mL loam soil inoculated with 750 mL bio-slurry doped with 10 mL of 10 ppm lambda cyhalothrin, chlorpyrifos and malathion pesticide solutions. The cathodic chamber was loaded with 1500 mL distilled water. The setup was incubated for a 90 days’ retention time where voltage and current were recorded daily using a multi-meter. The degradation level was assessed using a GC-MS after sample extraction using standard QuEChERs method.
 The voltage generated from the pesticide doped loam soil showed an upward trend from day 0 to day 15 in lambda cyhalothrin and malathion and from day 0 to day 20 in chlorpyrifos and pesticide mixture after which constant readings were observed for three days with downward trends thereafter. The maximum generated voltage was 0.537 V, 0.571 V, 0.572 V and 0.509 V in chlorpyrifos, lambda cyhalothrin, malathion and pesticide mix (MCL) respectively. The bioremediation levels for chlorpyrifos and malathion were 65.80 % and 71.32 %, respectively while no detectable, lambda cyhalothrin was observed after day 60 of the study. This study concludes that bioremediation of lambda cyhalothrin, chlorpyrifos and malathion in Limuru loam soil can be achieved using microbial fuel cells.

Removal of organochlorine pesticides by nanofiltration membranes modified with NH2-MWCNTs

Excessive use of pesticides and therefore the spread of pesticides in the environment with destructive effects on human and animal health is a very great problem in the world. In this study, the removal of three samples of organochlorine pesticides including aldrin, lindane, and endosulfan was investigated using nanofiltration membranes modified with NH2-MWCNTs. The properties of the prepared membranes were investigated by scanning electron microscopy (SEM), contact angle, water content, porosity, and mechanical strength. The performance of the membranes was evaluated by analysis of the rejection and flux of pesticide solutions at different pH. The addition of NH2-MWCNTs to the polymer matrix significantly improved the hydrophilic properties of the membranes and reduced the contact angle. Membrane flux was also improved by increasing the concentration of carbon nanotubes to 0.2 wt%. The highest flux at pH 10 is related to lindane pesticide. The modified membrane with 0.5 wt% functionalized carbon nanotubes showed a 98% rejection for endosulfan at neutral pH compared to the pure membrane. In the pH range experiment, lindane rejection was lower than of other pesticides. The steric hindrance due to the structure and molecular size of pesticides and interaction with membrane surface was very important in membrane efficiency. The M3 membrane with 0.3 wt% NH2-MWCNTs revealed high antifouling performance.

Synergistic mechanism and environmental behavior of tank-mix adjuvants to topramezone and atrazine.

An effective way to reduce herbicide quantity is to use adjuvants in order to optimize the amount of herbicide and improve its control efficiency. In order to screen for efficient herbicide tank-mix adjuvants, improve the control of weeds in maize fields, reduce the amount of effective ingredients, and improve the adsorption and digestion behavior of herbicides in soil, this study evaluated the synergistic effects and soil behavior of four types of tank-mix adjuvants combined with herbicides. Different types of adjuvants can enhance herbicide production. Surface tension was significantly reduced by 13% after the pesticide solution was applied with AgroSpred™ Prime. The contact angle with the foliar surface was significantly reduced and solution wettability improved using Atp Lus 245-LQ-(TH). The permeability of topramezone and atrazine in leaves of Amaranthus retroflexus L. and Digitaria sanguinalis (L.) Scop. was increased by 22-96% after adding either tank-mix adjuvant. The solution drying time and maximum retention on leaves were not affected by the tank-mix adjuvants. Ethyl and methylated vegetable oils can reduce the adsorption of topramezone in the soil, thus reducing its half-life in soil. The tank-mix adjuvants had no significant effect on soil dissipation or adsorption of atrazine. AgroSpred™ Prime and Atp Lus 245-LQ-(TH) have the best synergistic effect on topramezone and atrazine in the control of A. retroflexus L. and D. sanguinalis (L.) Scop. in maize fields.

Efektivitas Pestisida Nabati Daun Babadotan (Ageratum conyzoides L.) Terhadap Mortalitas Hama Wereng Coklat (Nilaparvata lugens Stal.) Pada Tanaman Padi

Oryza sativa L. is the main food crop in Indonesia. The need for rice continues to increase every year. Rice production in South Kalimantan in 2019 reached 790,449 tons of rice, then in 2020 it decreased to 677,105 tons of rice. One of the causes of the decline in rice productivity is the attack of the brown planthopper (Nilavarpata lugens Stall.). This research aims to determine the effectiveness of the herbal pesticide babadotan leaves on the mortality of brown planthopper pests on rice plants. This research was designed using a Completely Randomized Design (CRD). The factors tested were the administration of a herbal pesticide solution of babadotan leaves at doses of 3%, 6% and 9% with a control treatment that was not given pesnab and a chemical control as a comparison. This study had 5 treatments and 4 replications. The results of the study showed that administering 9% herbal pesticide solution from babadotan leaves was effective in controlling brown planthopper pests with a mortality value of 80%.

The potential capability of treated perlite for removal of penta chloro nitrobenzene

Abstract Perlite is an example of clayey type geologic mineral. Perlite is a cheap and abundant adsorbent and it can be used for versatile applications in food, pharmacy and chemistry industries. Perlite was chosen for the removal of penta chloro nitrobenzene (PCNB) pesticide. This pesticide is used for the control of fungi species in farming commonly. Adsorbent surface area and pore volumes were determined as 288.15 m2/g and 78.24 cm3/g (BET method). The characteristics of the adsorbent were furnished by evaluating the SEM and FTIR images. The adsorption equilibrium was reached in 80 min. Initial adsorbate concentration and pH of the medium were also investigated from this point of view. The experimental data were evaluated with proper isotherm models such as Langmuir, Freundlich and Halsey. Langmuir and Freundlich isotherms give the best results. Monolayer capacity was found as 238.095 mg/g. The kinetic mechanisms of the phenomon was analyzed by employing the pseudo first and second order models. Pseudo first order kinetic results were better than the second one with the higher regression coefficients and close experimental and calculated uptake values. Those values were found as 0.615 and 0.6587 mg/g for 1 μg/mL aqueous pesticide solution. Activation energy was found approximately 5094 J/mol which was shown a physisorption mechanism of the adsorption. Activation energy is also employed for interpreting the sticking probability factor. The thermodynamic of adsorption were also evaluated and found as −2.385 J/g at the room temperature. The negative Gibbs energy shows the feasibility and spontaneous nature of PCNB removal on perlite.

Research on a UAV spray system combined with grid atomized droplets.

UAVs for crop protection hold significant potential for application in mountainous orchard areas in China. However, certain issues pertaining to UAV spraying need to be addressed for further technological advancement, aimed at enhancing crop protection efficiency and reducing pesticide usage. These challenges include the potential for droplet drift, limited capacity for pesticide solution. Consequently, efforts are required to overcome these limitations and optimize UAV spraying technology. In order to balance high deposition and low drift in plant protection UAV spraying, this study proposes a plant protection UAV spraying method. In order to study the operational effects of this spraying method, this study conducted a UAV spray and grid impact test to investigate the effects of different operational parameters on droplet deposition and drift. Meanwhile, a spray model was constructed using machine learning techniques to predict the spraying effect of this method. This study investigated the droplet deposition rate and downwind drift rate on three types of citrus trees: traditional densely planted trees, dwarf trees, and hedged trees, considering different particle sizes and UAV flight altitudes. Analyzing the effect of increasing the grid on droplet coverage and deposition density for different tree forms. The findings demonstrated a significantly improved droplet deposition rate on dwarf and hedged citrus trees compared to traditional densely planted trees and adopting a fixed-height grid increased droplet coverage and deposition density for both the densely planted and trellised citrus trees, but had the opposite effect on dwarfed citrus trees. When using the grid system. Among the factors examined, the height of the sampling point exhibited the greatest influence on the droplet deposition rate, whereas UAV flight height and droplet particle size had no significant impact. The distance in relation to wind direction had the most substantial effect on droplet drift rate. In terms of predicting droplet drift rate, the BP neural network performed inadequately with a coefficient of determination of 0.88. Conversely, REGRESS, ELM, and RBFNN yielded similar and notably superior results with a coefficient of determination greater than 0.95. Notably, ELM demonstrated the smallest root mean square error.

A reliable quantification of organophosphorus pesticides in brown rice samples for proficiency testing using Japanese official analytical method, QuEChERS, and modified QuEChERS combined with isotope dilution mass spectrometry.

The objective of the present study is to provide reliable concentration values as assigned values for target pesticides in brown rice samples used in proficiency testing (PT) organized by the Hatano Research Institute (HRI). The test samples for PT were prepared by immersing brown rice in the pesticide solution and using a spray dryer by the HRI. Homogeneity and stability assessments were performed for PT samples, and the relative uncertainties due to inhomogeneity and instability were 0.58 %-0.78 % and 0 %-0.96 %, respectively. Quantification for the assigned values of target pesticides by the National Metrology Institute of Japan (NMIJ) was carried out using the multiple analytical methods including Japanese official analytical method, QuEChERS, and modified QuEChERS, which were combined with isotope dilution mass spectrometry, to ensure the reliability of the analytical results. The NMIJ assigned values were 0.065±0.004 mg/kg for chlorpyrifos, 0.217±0.012 mg/kg for diazinon, 0.138±0.008 mg/kg for fenitrothion, and 0.138±0.008 mg/kg for malathion.

Приготовление растворов различной концентрации

When preparing treatment solutions of fertilizers and pesticides for technological processes, one should mix liquids taking into account the precise dosing of components. However, the existing designs of dosing and mixing devices do not provide qualitative dosing. Moreover, a sharp increase of fraction quantity may result in a hydraulic impact. To eliminate these disadvantages, based on analytical research of available designs and patent search results, the authors worked out a mixer for preparing solutions of various concentrations. The device is also capable of changing the ratio of components in the process of operation. The device provides smooth change of preparation concentrations due to the design of dosing valves forming square-shaped ports with a changing configuration. The port plates move relative to each other both horizontally and vertically. The proposed device smoothly changes the concentration of the solution, thereby providing for more accurate dosing. It was experimentally found that a smoother change in the flow rate of treatment liquid according to the solution concentration is observed at a distance from the axes of symmetry of the dosing device disks to the rotation axis of the distribution ports, equal to 0.04 to 0.1 m. The deviation of the actual treatment liquid flow rate from the calculated one does not exceed 5%. The integration of the developed mixer into the systems of fertigation units, sprayers and other specialized machines will ensure better quality of the fine irrigation of plants, seeds, and soil.

Stability and computational analyses of selected pesticides in use in the Republic of Serbia

Pesticides commonly used in the Republic of Serbia (tebuconazole, pendimethalin, pyraclostrobin, propiconazole and famoxadone) have high stability, so their potential toxicity to humans needs to be investigated. These pesticides are in use in the Republic of Serbia in various formulations. Their toxicity and interactions with acetylcholinesterase were thoroughly investigated in this study using computational tools. The ADMET (adsorption, distribution, metabolism, excretion, toxicity) study showed that all of them are efficient oral compounds, and that pendimethalin was a mutagenic compound. Glide scores ranged from ?18.41 (pendimethalin) to ?27.61 kJ mol-1 (famoxadone) in Mus musculus, and from ?19.58 (pendimethalin) to ?24.31 kJ mol-1 (propiconazole) in Homo sapiens. In addition, the experimental stability of the pesticides solutions in methanol was studied using the fast gas chromatography?mass spectrometry (GC?MS, retention times of the studied pesticides ranged from 14.47 (pendimethalin) to 22 min (famoxadone)). They showed good stability over time, apart from pyraclostrobin which decomposed mainly into its desmethoxy derivative after 20 months. Based on the promising modelling results, pyraclostrobin and famoxadone emerge as potential candidates for further investigation in the treatment of Alzheimer?s disease, taking care to increase their stability.