Search Results (20)

Spray penetration into citrus canopies is critical for adequate coverage and deposition to ensure effective pest control. However, mismatch of air assistance to target canopy characteristics can lead to unintended spraying losses through overpenetration. To evaluate the effect of air assistance on on-target deposition, two sprayers (surrogates for airflow rates) were used to apply a fluorescent tracer dye solution @ a target concentration of 300 ppm to 16 medium-foliage-density tree blocks in a commercial mandarin orchard. The complete factorial experiment in three replications, also designed for validating a model-based spray decision support tool, comprised two forward travel speeds (1.6 and 4.8 km/h), two disc-core nozzles (TeeJet^® D3-25 and D6-45), and either one or two nozzle rows to obtain a wide range of application rates (496 to 9719 L/ha). Dye deposition significantly decreased with canopy depth (p =< 0.001) by nearly seven times across the 3.4 m wide canopies but was not significant over 1.2 to 2.2 m sampling height (p = 0.867). Deposition obtained with the low-airflow-rate sprayer was significantly greater (p =< 0.001) than that obtained with the high-airflow-rate sprayer over the dose range likely due to too much air pushing out spray droplets. This study underscores the importance of matching the air assistance of orchard sprayers to the target canopy. Full article

Remotely piloted aircraft (RPAs) have been increasingly used for crop protection in coffee plantations. However, the applications can result in low spray deposition on leaves and higher product losses between rows compared to ground airblast sprayers. This study aimed to evaluate the spray deposition on the coffee canopy and potential losses to the soil during application with an RPA and an airblast sprayer at varying spray volumes. The experiment comprised four spray treatments: RPA at 10 L ha⁻¹ and 20 L ha⁻¹, and airblast sprayer at 200 L ha⁻¹ and 300 L ha⁻¹. Leaf deposition was quantified by measuring a tracer on leaves from the lower and upper parts of the coffee canopy using spectrophotometry. Spray losses to the soil were measured by analyzing tracer residues on Petri dishes positioned within the inter-rows and beneath the coffee canopy. Statistical process control was used to analyze spray deposition quality in the study area. Ground-based airblast spraying resulted in the highest overall canopy deposition, while RPA spraying led to greater losses within the inter-rows. No significant difference was observed in spray runoff beneath the canopy between ground-based and aerial applications. Leaf deposition exhibited random variability across all application methods. Therefore, application stability, control, and spray quality standards were maintained. Full article

The use of plant protection products (PPPs) has become fundamental to guarantee excellent field productivity. Nevertheless, their usage presents critical issues, such as the quantity of substances used, the relative toxicity, and the contamination of nearby fields caused by atmospheric drift. This study focuses on the characterization of aerosol droplets of PPPs produced by spraying a chemical marker, fluorescein, with an orchard airblast sprayer equipped with conventional hollow cone (HC) and anti-drift air inclusion (AI) nozzles, using a wind tunnel as a controlled environment. A particle/droplet image analysis was employed to study the droplet production of the nozzles, while a liquid chromatography tandem mass spectrometry (HPLC-MS/MS) analysis allowed us to evaluate samples collected using a cascade impactor located at 5 m, 10 m, and 20 m from the emission point. Overall, HC nozzles are very accurate at producing specific drop size distributions (DSDs), while AI nozzles produce a much wider DSD, concentrating the largest part of the distributed volume into droplets of a larger size. The marker concentration was much lower for the AI nozzles compared to the HC nozzles; moreover, the two nozzles show a similar trend in the coarse droplet range, while significantly differing in the fine droplet spectrum. Full article

Pesticide application equipment (PAE) is the last part of the chain during the plant protection process. The use-phase of plant protection products (PPP) has been addressed in two EU Directives: 128/2009/EC and 127/2009/EC. This last one covers all the mandatory technical requirements to be fulfilled by new sprayers prior to their placement in the market. The objective of this research was to develop a potential decision support system (DSS) to evaluate and quantify the degree of implementation of all the required characteristics of new sprayers, including not only the mandatory requirements but also specifications widely described in the corresponding harmonized standard ISO 16119. It includes 10 independent elements of the sprayer, including a list of technical specifications listed in the applied standards ISO 16119 and ISO 16122. The relative influence of every one of the different elements has been quantified based on previous research. The algorithm enables the establishment of an objective relative classification of the sprayers to differentiate among different machines, mainly based on their quantified environmental contamination risk. The DSS can also discriminate among sprayers that should not reach the market due to their non-compliance with any of the mandatory requirements. Full article

Pesticide spraying using unmanned aerial vehicles (UAVs) has been utilized in many crops, including fruit tree crops, because of its merits in terms of labor-saving and the low risk to the operator. However, its relevance to chestnut, one of the commercially significant fruit trees grown throughout Europe and Asia, has not been studied. In this work, we assessed the effectiveness of UAV-based ultra-low-volume pesticide application in chestnuts. We demonstrated the efficiency of three insecticides applied by a UAV on young chestnut trees. Interestingly, using a reduced amount of one of the pesticides, UAV-based spraying had greater control efficacy than conventional methods. The efficacy of ultra-low-volume pesticide application to adult trees was equivalent to using an air-blast sprayer. The spray coverage was compared in terms of spray volume (20 L vs. 40 L ha⁻¹), flight method (straight flight vs. rotating flight for each tree), the size of the UAVs (8 L vs. 30 L in payload capacity), flow rate (3.8 L vs. 6.0 L min⁻¹), and tree age in order to characterize the droplet deposition of UAV-based spraying. Overall, we showed that spraying pesticides using a UAV could effectively protect chestnut trees. It was debated how tree training, or tree height, affected pest control. Full article

Spraying systems to protect crops against pests are still necessary to maintain food production at the rates demanded by the current population. However, today, it is crucial to use precision agriculture to reduce the negative effects of pesticides and other agrochemicals such as fungicides. In particular, pressure fluctuations related to transient states when using pulse-width-modulated nozzles (PMW) have been reported to decrease the accuracy of preset flow rates in air-assisted orchard sprayers. The objective of this paper is to analyze the vibrations induced in the spraying system of a vineyard blast sprayer controlled by pulse-width-modulated nozzles, considering the instantaneous duty cycle (DC) as the control variable. An air-assisted vineyard sprayer was modified to host 24 solenoid shutoff valves with hollow disc–cone nozzles. A triaxial accelerometer was mounted to track the effect of duty cycle (20%, 30%, 50%, and 70%). In addition to accelerations, high-speed images were recorded, and the pressure according to time and the flow were estimated. The hydraulic system of the sprayer, when controlled in real time by the PWM solenoids, created pulsating impacts at the nozzle level with the same frequency of 10 Hz of the PMW system. The impact effect was significantly higher for low duty cycles under 40% DC. In addition, to demonstrate the inaccuracy of opening and closing the valves at a precisely specified time, this study also confirmed the divergence between the theoretical duty cycles commanded by the sprayer’s control unit and the actual ones measured in real time. The results of the analysis showed the difficulty of opening and closing the valves with precision to obtain accurate duty cycles in the practical implementation of smart sprayers and the importance of understanding the vibration effects of pulses in arrangements of multiple PWM nozzles working simultaneously. Full article

Plot size, sample sufficiency, and number of repetitions are factors that affect the experimental errors or residuals and the expression of true differences among treatments. The objective of this study was to determine, using statistical models, the appropriate sample size for application technology experiments in coffee crops through the evaluation of foliar spray deposition and soil runoff in the ground-based application of pesticides. In the first stage, we determined the quantity of leaves per set and the volume of the solution for washing the leaves and extracting the tracer. We analyzed the variability between the coefficients of variation (CVs) of the amount of tracer extracted in two droplet classes (fine and coarse), for the different parts of the plants, and for the different quantities of leaves per set that were organized into intervals of five leaves (1–5, 6–10, 11–15, and 16–20). Less variability was found in the intervals with 10 leaves per set and using 100 mL of extraction solution. In the second stage, a field experiment was conducted using an entirely randomized design with 20 plots: 10 sprayed with fine droplets and 10 with coarse droplets. In each plot, 10 sets (samples) with 10 leaves each were collected from the upper and lower canopy of the coffee trees. Moreover, 10 Petri dishes were placed per plot and collected after application. Based on the results of the spray deposition (mass of tracer extracted per cm² of leaf), we determined the optimal sample size using the maximum curvature and maximum curvature of the coefficient of variation methods. Higher variabilities were related to the targets that are more difficult to reach. Thus, this study determined an optimal sample size between five and eight sets of leaves for spray deposition, and four to five Petri dishes for soil runoff. Full article

Panonychus ulmi (Koch) (Acari: Tetranychidae), commonly known as European red mite, is a polyphagous pest of various tree and small fruit crops, including apples. A field study was conducted to evaluate different pesticide options available for the management of P. ulmi, and their impact on the population of non-target predatory mite species complex consisting of Neoseiulus fallacis, Typhlodromus pyri, and Zetzellia mali in apple orchards. Pesticides were applied using a commercial airblast sprayer at the 3–5 mite/leaf recommended economic Integrated Pest Management (IPM) threshold or prophylactically in the spring ignoring IPM practices such as monitoring, reliance on biological control and economic thresholds. Effects on the motile and egg stages of P. ulmi were evaluated as were effects on the populations of predatory mites through frequent leaf counts during the season. We also recorded the subsequent overwintering eggs of P. ulmi from each pesticide treatment. The two prophylactic treatments containing a mixture of zeta-cypermethrin + avermectin B1 + 1% horticultural oil and abamectin + 1% horticultural oil provided effective control of P. ulmi population throughout the season without reducing predatory mite populations. In contrast, eight treatments applied at the recommended economic threshold of 3–5 mites/leaf were not effective in suppressing P. ulmi populations and most reduced predatory mites. Etoxazole had significantly higher number of overwintering P. ulmi eggs compared to all other treatments. Full article

The flowrate control of spraying systems with pulse-width-modulated solenoid valves is currently being implemented for precision herbicide application in commodity crops, but solutions for fruit trees set in orchards that require higher pressures are mostly in the development stage. A reason for this has been the higher flowrate and pressure requirements of blast sprayers used for dense canopies typical of high value crops. In the present study, the duty cycles preset by an operator were compared to the actual ones estimated from measuring flowrates. A new developed air-assisted orchard sprayer with shelf hollow disc-cone nozzles was studied, such that flowrates and pressures were registered by a computer for different duty cycles commanded by an operator from 10% to 100% in intervals of 10%. In addition to sensor data, visual assessment was carried out via high-speed video images. The results showed that preset duty cycles were always more than 10% lower than the actual DC estimated from measured flowrates. The effective operational range of the duty cycles went from 20% to 80%. In general, the deviations in transitional periods were higher for lower duty cycles, being difficult to determine the real reduction in flowrate during the transition periods. A correction model has been proposed to adjust the preset duty cycles to make sure that the necessary spray flowrate is released as precisely commanded by prescription maps. Further research will be needed to verify the proper implementation of the developed correction model in field applications. Full article

Orchard plant protection machinery in China still has a low application efficiency. Air-blast sprayers represent the primary development direction of pesticide applications in orchards. The spray control parameters have to be matched to the tree canopy status to achieve precise results. In this study, a vertical patternator was used to determine the accuracy of spraying fruit trees. The influences of three control parameters (blower speed, spray angle, and spray distance) on the spray performance of the air-blast sprayer were analyzed, and the volume of the spray was measured in collection plates at different heights. The quantitative relationship between the overall collection volume and the critical height collection volume was obtained for different parameter values, and the combined effects of any two control parameters on the collection performance and the position of the optimum collection area were obtained. The regression model describing the relationship between the collection volume in the critical height range and the three factors was established, and the main effects of the control parameters were determined. The results showed that if one parameter remained constant, the correlation between the other two parameters was non-significant. The collection volume in the critical height range increased initially and then decreased as the spray distance increased. The maximum collection volume was obtained at a spray distance of 1.762 m. The regression model can be used to obtain the optimum values of the parameters. Full article

Airblast sprayers are widely used for the application of plant protection products (PPP) in citrus. Adaptation of the vertical distribution of the spray cloud to the canopy (density, shape and size), is essential to deposit an adequate amount of PPP on the target and to reduce losses (drift, runoff). Vertical spray profiles of three air-assisted axial fan hydraulic sprayers with different configurations and settings were obtained to evaluate the effect of these settings on the vertical spray profile. From the analysis of the empirical results, the impact of operational settings (nozzle, air volume and flow rate) on treatment efficiency is assessed. The empirical database generated in this work has been employed to feed the Citrus VESPA model, a highly intuitive, web-based decision aid tool that helps farmers to easily estimate the vertical spray profiles generated by their particular sprayers and settings and how these influence deposition and potential drift. The tool can also be used to determine the effect and importance of adequately selecting, orienting and opening/closing nozzles and optimizing volume application rate and fan speed, in order to adjust the application to the actual vegetation, with the aim of saving resources and reducing risks to humans and the environment. Full article

Modern viticulture cannot be practiced without the use of plant protection products to control diseases like downy mildew, powdery mildew, and pests. In severely sloping vineyards, where mechanization is not possible, pesticide application is realized using spray guns, which is a laborious, expensive, and dangerous application technique. In these vineyards, where viticulture is defined as “heroic viticulture,” vine-growers could seriously take advantage of innovation in spray-technique applications. For this reason, several prototypes of a fixed spraying system (FSS) were realized in recent years. Two prototypes of a fixed spraying system were built in 2019 in two different vineyards in the Veneto region (north-eastern Italy). In both vineyards, the fixed spraying systems were used to perform pesticide application during the 2020 season to control downy mildew, powdery mildew, and pests. With this solution, both vineyards were successfully protected, resulting in comparable infection degrees and yields as the ones protected with airblast sprayers and spray guns. This study contributes to assert fixed spraying systems as an innovation that could improve working conditions, safety, timing, and performances of plant protection products’ application in heroic viticulture areas. Full article

Aonidiella aurantii is one of the most damaging armored scales in citrus crops worldwide. To control this pest, high water volume rates are conventionally used. In order to rationalize the pesticide applications in citrus, IVIA developed CitrusVol, a tool that recommends the optimal volume rate based on the vegetation, the pest or disease and the active ingredient. In this study the objectives were: (i) validate CitrusVol as a tool to adjust the spray volume to control A. aurantii and (ii) quantify its environmental and economical advantages. For this, the spray volume adjusted with CitrusVol was compared with the one conventionally used by farmers in 18 applications in seven orchards during two years. The following parameters were evaluated: (i) spray distribution in the canopy, (ii) A. aurantii males trapped per day, and (iii) number of scales per fruit at harvest. CitrusVol reduced the spray volume and the amount of pesticide by 35% on average. Despite this reduction, a satisfactory spray distribution was achieved, and the volume was found to control the pest in a comparable way to the conventional volume. Moreover, CitrusVol saved per application and on average 31.25 h/100 ha of spray operating time, 241.83 L/100 ha of fuel consumption and consequently, the reduction of emissions of CO₂ was 631.18 kg/100 ha. Therefore, CitrusVol allows for efficient, low-input and low-impact pesticide applications. Full article

Pesticides in three-dimensional (3D) crops are usually applied sidewise, so the vertical component must be considered for adjusting the applications. For this, different approaches have been proposed. Leaf Wall Area (LWA) was selected to express the minimum dose to be used in efficacy field trials for plant protection product (PPP) authorization in northern areas of Europe, where 3D crops are grown as narrow wall-forming structures. However, southern European areas also managed 3D crops as wide walls or globular crops with non-negligible canopy width. Therefore, a Tree Row Volume (TRV) model is thought to be more appropriate for dose expression. Furthermore, efficacy evaluations for pesticide authorization are usually carried out with manual sprayers in young plantations with medium-sized trees. However, growers normally apply PPP with air-blast sprayers in plantations of different tree sizes. The objective of this study was to determine which dose expression is more suitable in citrus orchards, as well as to analyze, in turn, the influence of the sprayer. The results demonstrated that TRV was the most appropriate for dose expression. Knapsacks and air-blast sprayers distributed the spray on the canopy in different ways, and the size of the vegetation influenced the differences between them. Moreover, knapsack sprayers produced higher ground losses, and air-blast sprayers produced higher potential drift. Full article

Organic production of pears is challenging in part because OMRI (Organic Materials Review Institute) approved biopesticides are short lived when applied as foliar sprays. Trunk injection is an alternative method of insecticide delivery that may enhance the performance of biopesticides for control of pear psylla. The objective of this study is to compare the efficacy of azadirachtin and abamectin in the control of pear psylla using two different application methods, airblast sprayer and trunk injection. Trunk injections of azadirachtin and abamectin were compared to airblast applications of equal labeled rates on 33-year-old Bartlett Pear trees (Pyrus communis L., var “Bartlett”). The azadirachtin and abamectin trunk injected treatments performed equally or better than the two airblast applications in the control of the pear psylla. The trunk injected trees from the first season provided a moderate level of control into the second season, one year after the injections. This study suggests that trunk injection is a superior delivery system for biopesticides used in organic pear production. Full article