Pesticide Application Efficiency Research Articles

Development of remote-controlled solar-powered pesticide sprayer vehicle

Pest species pose a significant threat to the agricultural industry as they can negatively impact crop productivity and result in potential financial losses due to damage. This research aims to address agricultural challenges in the local area and improve the efficiency of pesticide application. A solar-powered, remote-controlled, semi-automated knapsack sprayer vehicle has been developed to address this issue. It operates using a 100 AH battery that is charged by four 30W solar panels connected in tandem to produce 120 W, providing power to the motors and pump. The vehicle uses a 12 V hub motor to drive the back and steer the front and is equipped with a 12 V window regulator/wiper motor. The vehicle is controlled by a remote control and an HC-05 transmitter and receiver, programmed with an ATMEGA32A linked to a relay board. The vehicle utilizes a 116 psi ≈ 799.8 kPa pump for the sprayer. Results indicate that as the feed pressure increases, the flow rate steadily rises and reaches 4 L per minute at the 799.8 kPa pump. With a pump spray rate of 5 L per minute when increased and a pesticide tank capacity of 20 L, the vehicle can spray for a total of 4 min and cover 159 m. Employing a remote control reduces the need for manual labour, making pesticide spraying more consistent, efficient, and productive. The sprayer also saves time compared to traditional methods and poses no harm to the operator.

Spray deposition in an artificial grapevine canopy as affected by spray angle regulation systems of radial airflow air-assisted sprayers

As the most critical factor affecting pesticide application efficiency and drift risk, the airflow characteristics of air-assisted sprayers have been of great concern. This study compared seven assisted airflow angle regulation methods regarding within-canopy deposition quality and off-target losses to the ground and behind the target canopies, including a newly proposed airflow swing device, three types of directional housings, and airflow deflector settings. An artificial grapevine canopy and a multiple-tracer methodology were used to evaluate deposition. Results showed that airflow angle regulation methods caused significant differences in canopy deposition and off-target losses (p < 0.001). The sprayer equipped with 0° housing had the highest deposition on the canopy (122.27 μg cm−2), followed by the sprayer equipped with the −30° housing (99.26 μg cm−2). The sprayer equipped with both airflow swing devices and optimal deflectors had a deposition of 87.76 μg cm−2. The radial airflow air-assisted sprayer without any airflow interventions caused the highest off-target losses, reaching 31.95% of the total spraying volume. The optimal deflector setting was conducive to reducing ineffective losses, but it also deteriorated the deposition uniformity on the canopy. Significantly, the airflow swing device improved the deposition uniformity on the abaxial side of the leaves to 23.89%, which can provide a reference for future optimization of new air-assisted sprayers.

Development and Optimization of Operational Parameters for Tractor-Operated Boom Sprayer for Field Crops

Spraying is a crucial practice in agriculture, especially for the application of chemical pesticides that play a vital role in protecting crops. However, there has been a worrisome rise in the annual consumption of pesticides, leading to significant concerns. The excessive use of these pesticides has resulted in substantial wastage, which is a cause for alarm. To address these issues and enhance the efficiency of pesticide application, a tractor-operated boom sprayer was developed to ensure effective spraying. The study focused on evaluating and optimizing three operational factors: spacing between nozzles (30, 40, 50 cm), spray boom height (80, 90, 100 cm), and pressure (17.5, 21.0, 24.5 kg.cm-2). A factorial Completely Randomized Design (CRD) approach was employed, 81 experiments were conducted and data were analyzed statistically by using the SPSS software package to investigate the effect of operational parameters on the performance of the sprayer. The results revealed that the operational parameters were significantly influencing the swath width and percent of overlap during spraying. The optimum combination of operational parameters was obtained using the R-software, the optimum combination for obtaining maximum swath width and minimum overlap is spacing between nozzles at 50 cm, spray boom height at 90 cm, and operating pressure at 24.5 kg.cm-2. The swath width and overlap at optimum combination were 7.77m and 43.12%, respectively. Implementing this optimal combination significantly improved the performance of the spraying activity, ensuring better coverage.

Generalizing routes of plant exposure to pesticides by plant uptake models to assess pesticide application efficiency

Pesticide application techniques are critical not only for integrated pest management (IPM) but also for food and environmental safety. Assessing pesticide application efficiency on plants can help optimize IPM and reduce pesticide environmental impacts. With hundreds of pesticides registered for use in agriculture, this study proposed a modeling approach based on plant uptake models for generalizing routes of plant chemical exposures that can correspond to different types of pesticide application methods and evaluating their respective efficiency on plants. Three representative pesticide application methods (i.e., drip irrigation, foliar spray, and broadcast application) were selected for modeling simulations. The simulation results for three representative pesticides (i.e., halofenozide, pymetrozine, and paraquat) revealed that the soil-based transpiration exposure route facilitated the bioaccumulation of moderately lipophilic compounds in leaves and fruits. While the plant surface-based exposure route (i.e., leaf cuticle penetration) made it easier for highly lipophilic compounds to enter plants, moderately lipophilic pesticides (i.e., log KOW ∼ 2) were more soluble in phloem sap, which enhanced their subsequent transport within plant tissues. In general, moderately lipophilic pesticides had the highest simulated residue concentrations in plant tissues for the three specific application methods, indicating they had the highest application efficiency due to their enhanced uptake routes (via transpiration and surface penetration) and increased solubility in xylem and phloem saps. Compared to foliar spray and broadcast application, drip irrigation produced higher residue concentrations for a wide variety of pesticides, exhibiting the highest application efficiency for many pesticides, especially for moderately lipophilic compounds. Future research should incorporate plant growth stages, crop safety, pesticide formulations, and multiple application events into the modeling approach for understanding pesticide application efficiency evaluation.

Extending shared socio-economic pathways for pesticide use in Europe: Pest-Agri-SSPs

While pesticides are essential to agriculture and food systems to sustain current production levels, they also lead to significant environmental impacts. The use of pesticides is constantly increasing globally, driven mainly by a further intensification of agriculture, despite stricter regulations and higher pesticide effectiveness. To further the understanding of future pesticide use and make informed farm-to-policy decisions, we developed Pesticide Agricultural Shared Socio-economic Pathways (Pest-AgriSSPs) in six steps. The Pest-Agri-SSPs are developed based on an extensive literature review and expert feedback approach considering significant climate and socio-economic drivers from farm to continental scale in combination with multiple actors impacting them. In literature, pesticide use is associated with farmer behaviour and practices, pest damage, technique and efficiency of pesticide application, agricultural policy and agriculture demand and production. Here, we developed PestAgri-SSPs upon this understanding of pesticide use drivers and relating them to possible agriculture development as described by the Shared Socio-economic Pathways for European agriculture and food systems (Eur-Agri-SSPs).The Pest-AgriSSPs are developed to explore European pesticide use in five scenarios representing low to high challenges to mitigation and adaptation up to 2050. The most sustainable scenario (Pest-Agri-SSP1) shows a decrease in pesticide use owing to sustainable agricultural practices, technological advances and better implementation of agricultural policies. On the contrary, the Pest-Agri-SSP3 and Pest-Agri-SSP4 show a higher increase in pesticide use resulting from higher challenges from pest pressure, resource depletion and relaxed agricultural policies. Pest-Agri-SSP2 presents a stabilised pesticide use resulting from stricter policies and slow transitions by farmers to sustainable agricultural practices. At the same time, pest pressure, climate change and food demand pose serious challenges. Pest-Agri-SSP5 shows a decrease in pesticide use for most drivers, influenced mainly by rapid technological development and sustainable agricultural practices. However, Pest-Agri-SSP5 also presents a relatively low rise in pesticide use driven by agricultural demand, production, and climate change. Our results highlight the need for a holistic approach to tackle pesticide use, considering the identified drivers and future developments. The storylines and qualitative assessment provide a platform to make quantitative assumptions for numerical modelling and evaluating policy targets.

Study on Interaction Analysis Method between Fog Drops and Tree Trunk Surface for Precision Pesticide Application by Plant Protection UAV

In order to improve pesticide application efficiency and reduce environmental pollution, precise pesticide application has become the core concept of forestry pest control. In this paper, based on the precise target research requirements of the pesticide liquid of plant protection UAV, the VOF model of droplet impact was established. The two-phase flow model was used to simulate the three processes (contact, spread and contraction) of droplet impact on bark, and analyse the state of droplet impact on bark surface at different speeds and heights. Through the study, the behaviour state of fog droplets in different conditions can be obtained, which can maximize the use of liquid medicine, reduce environmental pollution, and provide a new research method for fog droplets deposition on tree trunk surface.

Reducing the Nursery Pesticide Footprint with Laser-guided, Variable-rate Spray Application Technology

Nursery producers are challenged with growing a wide range of species with little to no detectable damage from insects or diseases. Growing plants that meet consumer demand for aesthetics has traditionally meant routine pesticide application using the most time-efficient method possible, an air-blast sprayer, despite its known poor pesticide application efficiency. New variable-rate spray technology allows growers to make more targeted applications and reduce off-target pesticide loss. In this study, a prototype laser-guided variable-rate sprayer was compared with a traditional air-blast sprayer. Pesticide volume, spray application characteristics, and the control of powdery mildew were evaluated over the course of two growing seasons. Spray application characteristics were assessed using water-sensitive cards (WSCs) and DepositScan software. This prototype sprayer reduced pesticide volume by an average of 54% across both years despite being tested against a low rate (&lt;250 L⋅ha−1). In 2016, the conventional sprayer had more than double the deposit density on target WSCs among distal trees than the variable-rate sprayer; however, within proximal trees, there was no difference between the two sprayer types. In 2017, when the trees were larger, within both the distal and proximal trees, the conventional sprayer had greater deposit density on target WSCs than the variable-rate sprayer. In 2016, coverage on target WSCs was nearly 7-fold greater with the conventional treatment than with the variable-rate treatment. In 2017, when trees were larger, there was greater coverage on target WSCs in proximal trees (3.8%) compared with those in distal trees (1.0%) regardless of the sprayer type. This variable-rate spray technology provided acceptable control of powdery mildew severity on individual branches and whole trees and maintained the incidence of powdery mildew to levels comparable to that occurring among trees sprayed with a traditional air-blast sprayer. Therefore, the variable-rate spray technology has the potential to effectively control disease, dramatically reduce the pesticide footprint, and preserve natural resources such as ground and surface water, soil, and beneficial insects found within and around nurseries.

Reducing ground and airborne drift losses in young apple orchards with PWM-controlled spray systems

Pulse Width Modulated (PWM) solenoid valves can be used to control nozzle flow rates for precision spray applications to reduce pesticide use, thereby reducing environmental risk and production cost. Field tests in a two-year-old young apple orchard were conducted to investigate spray losses to the ground and in the air for an air-blast sprayer equipped with three spray systems: 1) manually controlled constant-rate system enabled with the PWM spray system (Manual-PWM), 2) laser-guided variable-rate system enabled with the PWM spray system (Laser-PWM); and 3) conventional constant-rate system with disabled PWM valves (Disabled-PWM). Artificial targets (plastic plates and water sensitive papers) were placed under twelve trees randomly selected from four rows of the orchard to collect spray losses to the ground. Airborne spray losses were determined by using nylon screens, mounted at five heights on each of seven poles distributed at different distances from the first sprayed row. Laser-PWM and Manual-PWM produced significantly lower airborne and ground spray drift losses inside and outside the orchard than Disabled-PWM, and these losses decreased significantly as the distance away from the first sprayed row increased. Laser-PWM reduced the total airborne drift by 90.3% and total ground loss by 85.0% compared to Disabled-PWM whereas Manual-PWM decreased the same airborne and ground drift by 84.1% and 7.9%, respectively. Disabled-PWM produced detectable airborne losses that reached 88.4 m away from where the sprayer was operated. Thus, the air-blast orchard sprayer equipped with PWM solenoid valves controlled by either the automatic laser-guided system or manual system would have great potentials to improve pesticide application efficiency with significant reductions in both pesticide consumption in young apple orchards, and off-target drift loss to the environment.

Evolution and Efficiency Assessment of Pesticide and Fertiliser Inputs to Cultivated Land in China.

Excessive use of pesticides and fertilisers has been a key issue limiting sustainable agricultural development. China is a typical pesticide- and chemical-fertiliser-dependent agricultural production area. We have matched the target indicators related to sustainable agricultural development (SDG1 and SDG2) and analysed the gap between China and four developed countries in terms of fertiliser and pesticide use intensity and efficiency from 2002 to 2016. We have used an improved Logarithmic Mean Divisia Index model and cluster analysis to identify the factors and effects driving increased pesticide and fertiliser inputs in China, and we discuss the exploratory effects of different provinces in reducing pesticide and fertiliser application and increasing efficiency. The findings reveal that (1) China is a typical pesticide- and fertiliser-dependent agricultural production area. The average combined fertiliser application efficiency in China from 2002 to 2016 was only 28% of that of the Netherlands, and the country’s average combined pesticide application efficiency was only 35% of that of the USA. (2) The most important of the three main drivers of the increase in pesticide and fertiliser inputs in China is the value added of the primary industry, contributing 56% for the period 2007–2016. (3) Further analysis at the provincial level according to four types—high-intensity high-yield type, high-intensity low-yield type, low-intensity high-yield type, and low-intensity low-yield type—clarified the provinces that should be focused on at the national level in terms of pesticide and fertiliser application reduction and efficiency increase in the future.

Assessing Nozzle Geometry, Spacing and Height Effect on Pesticide Spray Characteristics and Swath from Ground and Aerial Sprayers

Nozzle is the basic aperture that controls pesticide spray jet onto targeted substrates. It is moulded from stainless steel, brass, ceramic and plastics at different wear rates. The efficiency of pesticide application is dependent on chemical efficacy and nozzle type. Both flat fan and hollow cone nozzles are commonly used to enhance pesticide spray characteristics and deposition. The surface coverage and spray distribution are influenced by nozzle spacing and spraying height. Therefore, using a nozzle type, spacing and spraying height that give pesticide spray-overlap is of interest to researchers. This review therefore analyses the effect of nozzle geometry, nozzle spacing and spraying height regimes on pesticide spray droplets characteristics from mechanical boom sprayers. To improve on uniformity of pesticides spray coverage on plant surfaces, a unitary relative span is reported suitable for application, but there had not been clearly defined nozzle type, spacing and height regime for effective spraying. The review further proposes an optimum parameters combination with specific nozzle type, spacing and spraying height for efficient application of pesticides.

Numerical Simulation on Deposition of Atomization Droplet of Air-assist Boom Spraying in Air Flow

Air-assist Boom Spraying is a crucial technique and spray method of plant protection which has a significant effect on improving the efficiency of pesticide application and reducing droplet drift. Spraying drift is the main reason for the low utilization rate of pesticides, at the same time, the interaction of natural wind and the air bag wind is the main cause of spray drift. But at present, the regularity of spray droplet deposition and motion trajectory under the common influence of natural wind and air bag wind is not yet clear. The kinematics characteristics of the droplets deposition of air-assist boom spraying in the plants is investigated with numerical simulation method. The Phase Doppler Particle Analyzer (PDPA) is used to validate the numerical simulation results and it indicates that the deposition process can be well reproduced. The results show that the bigger droplets (>150 μm) get more kinetic energy from the vertical airflow and locate in windward side. These droplets are not sensitive to the horizontal airflow and are easier to deposit within a short time. The droplets with smaller size (<150 μm) are minimally influenced by the vertical airflow and suspend in the upside of the flow field. The vertical airflow not only prevents the horizontal airflow drift the droplets, but also introduces a vortex region near the canopy of the plants, which rotates the plant canopy and increases the droplet deposition on backside of the leaves. This study improves the understanding of the droplets deposition under the multi-wind fields and provides the theoretical basis for the innovation of the air-assist boom spraying system.

Metaldehyde prediction by integrating existing water industry datasets with the soil and water assessment tool

Metaldehyde (a synthetic aldehyde pesticide used globally in agriculture) has been internationally identified as an emerging contaminant of concern. This study aimed to integrate existing water industry, publicly available and purchased licensed datasets with the open-access Soil and Water Assessment Tool (SWAT), to establish if these datasets could be used to effectively model metaldehyde in river catchments. To achieve the study aim, a SWAT model was developed and calibrated for the River Medway catchment (UK). The results of calibration (1994–2004) and validation (2005–2016) of average daily streamflow (m3/s) showed that the SWAT model could simulate water balance well (P-factor 0.68–0.85 and R-factor 0.54–0.82, NSE 0.42–0.60). Calibration (P-factor 0.72 and R-factor 1.35, NSE 0.31) and validation (P-factor 0.49 and R-factor 1.37, NSE 0.16) for daily soluble metaldehyde (mg active ingredient) load was also satisfactory. The most sensitive pesticide parameters for metaldehyde simulation included the timing and amount of pesticide (kg/ha) applied to the hydrological response units, the pesticide percolation coefficient and pesticide application efficiency. Outputs from this research demonstrate the potential application of SWAT in large complex catchments where routine monitoring is in place, but isn’t designed explicitly for the purpose of predictive modelling. The implications of this, are significant, because they suggest that SWAT could be applied universally to catchments using existing water industry datasets. This would allow more efficient use of historical datasets and would be applicable in situations where resources are not available for additional targeted monitoring programmes.

Impact and Adhesion of Surfactant-Amended Water Droplets on Leaf Surfaces Related to Roughness

Highlights The relationship between impacting droplet deposition and leaf surface roughness was examined. Complete deposition occurred on smooth leaves with roughness heights shorter than 1.5 micrometers. Droplet deposition on rough leaves was best achieved at low initial travel speeds and high surfactant concentrations. This research provides understanding of increasing droplet adhesion on plants for pesticide spray applications. Abstract. Understanding the effects of the microscopic-scale surface roughness of targeted leaves on spray droplet retention and spread can help develop optimal strategies to improve pesticide application efficiency. Improved spray deposition would minimize the amounts of chemicals to be applied and reduce off-target losses and production costs while protecting the environment. A 3D optical surface profiler was used to measure the arithmetic mean roughness height (Sa), providing a reliable metric for microscopic-scale leaf surface roughness. The relationship between leaf surface roughness and droplet deposition was examined by correlating droplet adhesion with the Sa of six leaf types for spray solutions at five surfactant concentrations (0.0% to 0.75%) and eight initial droplet horizontal travel speeds (0.5 to 4.5 m s-1). Leaf roughness and wettability, in terms of Sa and contact angle (θc), ranged from smooth and easy-to-wet to rough and difficult-to-wet (37° 1.6 μm), deposition decreased with increasing Sa and initial droplet horizontal flight velocity, while it increased as surfactant concentration increased. Thus, spray deposition on rough leaf surfaces could be greatly improved with slow initial droplet flight speeds and high surfactant concentrations. In contrast, greater deposition on smoother leaf surfaces could be achieved at any initial droplet flight velocity and with low concentrations of non-ionic surfactant, or possibly none.

Impact of heat stress on development and fertility of Drosophila suzukii Matsumura (Diptera: Drosophilidae)

Drosophila suzukii is a globally invasive fruit pest that costs millions in yield losses and increased pest management costs. Management practices for D. suzukii currently rely heavily on calendar-based applications of broad-spectrum insecticides, but decision-based applications are theoretically possible with refined population modeling and monitoring. Temperature conditions are strongly deterministic of insect growth rates, fecundity, fertility, and resulting population densities. Therefore, information about the effects of temperature can be incorporated into population modeling to accurately predict D. suzukii population densities in the field which is crucial to maximize pesticide application efficiency and improve sustainability. Here, we investigated the effects of chronic heat stress during all of juvenile development on egg-to-adult viability and fertility. We also investigated egg-to-adult viability under heat stress after heat shock of the maternal parent. We found that heat stress during development results in lower egg-to-adult viability, and reduced lifespan and fertility for surviving adults. However, heat-shock treatment of females prior to egg laying increased the egg-to-adult viability of their eggs under heat stress. Female flies that developed at 30 °C had smaller ovaries than the untreated group and male flies had less sperm in their testes, and no sperm in their seminal vesicles. We conclude that heat stress during development is likely to have negative effect on D. suzukii population dynamics in the field. However, the intensity of such negative impact will depend on the phenotypic state of their maternal parents.

Enhancing Localized Pesticide Action through Plant Foliage by Silver-Cellulose Hybrid Patches.

Efficacy and efficiency of pesticide application in the field through the foliage still face many challenges. There exists a mismatch between the hydrophobic character of the leaf and the active molecule, low dispersion of the pesticides on the leaves' surface, runoff loss, and rolling down of the active molecules to the field, decreasing their efficacy and increasing their accumulation to the soil. We produced bacterial cellulose-silver nanoparticles (BC-AgNPs) hybrid patches by in situ thermal reduction under microwave irradiation in a scalable manner and obtaining AgNPs strongly anchored to the BC. Those hybrids increase the interaction of the pesticide (AgNPs) with the foliage and avoids runoff loss and rolling down of the nanoparticles. The positive antibacterial and antifungal properties were assessed in vitro against the bacteria Escherichia coli and two agro-economically relevant pathogens: the bacterium Pseudomonas syringae and the fungus Botrytis cinerea. We showed in vivo inhibition of the infection in Nicotiana benthamiana and tomato leaves, as proven by the suppression of the expression of defense molecular markers and reactive oxygen species production. The hydrogel-like character of the bacterial cellulose matrix increases the adherence to the foliage of the patches.

Modeling Pesticide and Sediment Transport in the Malewa River Basin (Kenya) Using SWAT

Understanding the dynamics of pesticide transport in the Malewa River and Lake Naivasha, a major fresh water resource, is critical to safeguard water quality in the basin. In this study, the soil and water assessment tool (SWAT) model was used to simulate the discharge of sediment and pesticides (notably the organochlorine residues of lindane, methoxychlor and endosulfan) into the Malewa River Basin. Model sensitivity analysis, calibration and validation were performed for both daily and monthly time steps using the sequential uncertainty fitting version 2 (SUFI-2) algorithm of the SWAT-CUP tool. Water level gauge data as well as a digital turbidity sensor (DTS-12) for suspended sediment transport were used for the SWAT calibration. Pesticide residues were measured at Upper and Down Malewa locations using a passive sampling technique and their quantity was determined using laboratory gas chromatography. The sensitivity analysis results showed that curve number (CN2), universal soil loss equation erodibility factor (USLE-K) and pesticide application efficiency (AP_EF) formed the most sensitive parameters for discharge, sediment and pesticide simulations, respectively. In addition, SWAT model calibration and validation showed better results for monthly discharge simulations than for daily discharge simulations. Similarly, the results obtained for the monthly sediment calibration demonstrated more match between measured and simulated data as compared to the simulation at daily steps. Comparison between the simulated and measured pesticide concentrations at upper Malewa and down Malewa locations demonstrated that although the model mostly overestimated pesticide loadings, there was a positive association between the pesticide measurements and the simulations. Higher concentrations of pesticides were found between May and mid-July. The similarity between measured and simulated pesticides shows the potential of the SWAT model as initial evaluation modelling tool for upstream to downstream suspended sediment and pesticide transport in catchments.

Design and performance evaluation of a variable-rate orchard sprayer based on a laser-scanning sensor

To improve the precision spraying strategy and reduce excessive pesticide application in orchards, an air-assisted sprayer integrated with a laser-scanning system was developed to realize the toward-target variable-rate spraying. In the spray control system, a method of calculating canopy gridding volumes was designed to ensure the canopy was divided into a uniform grid size, a variable-rate spray model was used in the flow rate decision software to control the spray output according to the canopy gridding volumes and travel speed, and a method of saving and accessing spray data was used to control the spray delay. The effects of different grid sizes and travel speeds on the spray performance were evaluated by quantifying spray coverage uniformity inside tree canopies. The results showed that spray coverage uniformity declined with increasing grid width from 0.14 to 0.28 m although the mean spray coverage on each target location showed no significant differences. Additionally, there were no significant variations in mean spray coverage at speeds of 1.0, 1.2 and 1.4 m/s for a tested tree of 1.6 m width and at any experimental speeds for a tested tree of 1.3 m width, which indicated that the variable-rate sprayer could provide good spray coverage uniformity under various travel speeds with a canopy size limitation. Compared with the same sprayer without the variable-rate spray function, the intelligent sprayer prototype realized effective toward-target spraying and avoided overspraying while providing sufficient spray coverage. Keywords: laser-scanning sensor, variable-rate spray, orchard, precision sprayer, pesticide application efficiency DOI: 10.25165/j.ijabe.20191206.4174 Citation: Cai J C, Wang X, Gao Y Y, Yang S, Zhao C J. Design and performance evaluation of a variable-rate orchard sprayer based on a laser-scanning sensor. Int J Agric & Biol Eng, 2019; 12(6): 51–57.

Technical efficiency of pesticide application on tomato, chinese cabbage and cauliflower in simpang empat sub-district Karo Regency

Prior research by authors on the use of pesticides and their impact on 75 vegetable farmers in Simpang Empat subdistrict, Karo district, North Sumatra showed that 60% of respondents applied pesticides in excess of the packaging instructions. Respondents were also found not to use a complete protective device. Almost 70% of respondents have mild toxicity complaints, and based on blood cholinesterase levels are also found most respondents have mild toxicity. Pesticide residue test results also found 0.728 residues of chlorpyrifos and 0.321 profenofos in vegetables produced in this area. This led to continued review by checking the technical efficiency in the use of pesticides. The method used is a quantitative method with the Data Envelope Analysis (DEA) approach to analyze technical efficiency of pesticide on each commodity. The population is the whole vegetable farmer who grew tomatoes, Chinese cabbage and cauliflower at the time of the study. The entire population is used to be a sample of 35 tomato and cauliflower farmers and 20 Chinese cabbage farmers. The results of the study indicate that the uses of pesticide as production inputs on tomato commodities, Chinese cabbage and cauliflower are not technically efficient. It is suggested to farmers to use pesticide input according to the rules, proper dosage, on target, on time, the right way so that pesticide used is technically efficient.

Development of real-time laser-scanning system to detect tree canopy characteristics for variable-rate pesticide application

Improving pesticide application efficiency is increasingly important in orchard spraying. In this study, a laser-scanning system was designed to acquire gridding volumes of a tree to quantify the geometry characteristics of the tree canopy in real-time. A laser-scanning sensor mounted on a linear guide was utilized to measure the structure of a target tree canopy. A computer was used to receive measurement data from the laser scanner and obtain the movement distance of the laser-scanning sensor from a controller. An algorithm written with VC# program was designed to calculate gridding volumes of trees by recognizing valid measurement data from the laser scanner. Laboratory evaluations were conducted on three kinds of regular objects, and the maximum relative errors of section volumes of the cuboid, triangular prism and cylinder objects were 3.3%, 7.9% and 9.4%, respectively, which illustrated that the algorithm could calculate the section volumes in different parts of the objects with high accuracy. A conifer tree and an apple tree were chosen to verify detecting accuracy of the laser-scanning system at variable speeds and grid sizes. The variation coefficients of total volumes for each kind of the tree were 0.078 and 0.041, respectively, which indicated that the laser-scanning system could be applied to provide the gridding volumes of different canopy densities in real-time with good reliability for guiding a variable-rate sprayer. Keywords: laser-scanning system, sensor, tree canopy, variable-rate spray, pesticide application efficiency, gridding volumes, calculation algorithm DOI: 10.25165/j.ijabe.20171006.3140 Citation: Cai J C, Wang X, Song J, Wang S L, Yang S, Zhao C J. Development of real-time laser-scanning system to detect tree canopy characteristics for variable-rate pesticide application. Int J Agric & Biol Eng, 2017; 10(6): 155–163.

Population and Spectrum of Droplets Produced During Electrostatic Spraying and Hydraulic Spraying Using Air Assistance

The droplet population produced during spraying influences the efficiency of pesticide application. It is possible to define a minimum number of droplets per unit area depending on the treatment and product to be applied. This study aimed to evaluate the characteristics of the populations and the spectra of droplets produced during electrostatic and air-assisted spraying. Factors including types of nozzles, spray volume, type of spray and its influence on the percentage coverage and density of droplet population. The experiment was arranged in a 2 x 2 x 2 factorial [two types of nozzles (Jacto JA-4, hollow cone and Jacto AXI-110-04, flat fan nozzle tip), two spray volumes (200 L ha -1 and 400 L ha -1 ) and two sprayer types (air-assistance in the spraying sleeve boom and electrostatic spraying)] in a randomized block design with four replications. The electrostatic sprayer increased droplet density per cm 2 of leaf.