Littérature scientifique sur le sujet « Calibration of sprayers »

Abstract Pesticide spray drift represents an important exposure pathway that may cause illness among orchard workers. To strike a balance between improving spray coverage and reducing drift, new sprayer technologies are being marketed for use in modern tree canopies to replace conventional axial fan airblast (AFA) sprayers that have been used widely since the 1950s. We designed a series of spray trials that used mixed-effects modeling to compare tracer-based drift volume levels for old and new sprayer technologies in an orchard work environment. Building on a smaller study of 6 trials (168 tree rows) that collected polyester line drift samples (n = 270 measurements) suspended on 15 vertical masts downwind of an AFA sprayer application, this study included 9 additional comparison trials (252 tree rows; n = 405 measurements) for 2 airblast tower sprayers: the directed air tower (DAT) and the multi-headed fan tower (MFT). Field-based measurements at mid (26 m) and far (52 m) distances showed that the DAT and MFT sprayers had 4–15 and 35–37% less drift than the AFA. After controlling for downwind distance, sampling height, and wind speed, model results indicated that the MFT [−35%; 95% confidence interval (CI): −22 and −49%; P < 0.001] significantly reduced drift levels compared to the AFA, but the DAT did not (−7%; 95% CI: −19 and 6%; P = 0.29). Tower sprayers appear to be a promising means by which to decrease drift levels through shorter nozzle-to-tree canopy distances and more horizontally directed aerosols that escape the tree canopy to a lesser extent. Substitution of these new technologies for AFA sprayers is likely to reduce the frequency and magnitude of pesticide drift exposures and associated illnesses. These findings, especially for the MFT, may fit United States Environmental Protection Agency’s Drift Reduction Technology (DRT) one-star rating of 25–50% reduction. An ‘AFA buyback’ incentive program could be developed to stimulate wider adoption of new drift-reducing spray technologies. However, improved sprayer technologies alone do not eliminate drift. Applicator training, including proper sprayer calibration and maintenance, and application exclusion zones (AEZs) can also contribute to minimizing the risks of drift exposure. With regard to testing DRTs and establishing AEZs, our study findings demonstrate the need to define the impact of airblast sprayer type, orchard architecture, sampling height, and wind speed.

This paper presents a method to infer the quality of sprayers based on data collection of the drop spectra and their physical descriptors, which are used to generate a knowledge base to support decision-making in agriculture. The knowledge base is formed by collected experimental data, obtained in a controlled environment under specific operating conditions, and the semantics used in the spraying process to infer the quality in the application. The electro-hydraulic operating conditions of the sprayer system, which include speed and flow measurements, are used to define experimental tests, perform calibration of the spray booms and select the nozzle types. Using the Grubbs test and the quartile-quartile plot an exploratory analysis of the collected data was made in order to determine the data consistency, the deviation of atypical values, the independence between the data of each test, the repeatability and the normal representation of them. Therefore, integrating measurements to a knowledge base it was possible to improve the decision-making in relation to the quality of the spraying process defined in terms of a distribution function. Results shown that the use of advanced models and semantic interpretation improved the decision-making processes related to the quality of the agricultural sprayers.

The study aimed to determine an optimum angle for the nozzles axial-flow sprayers a deposition for better vertical distribution focused on cashew. In laboratory tests were conducted adjusting the angle of the nozzle axial-flow sprayers. The experimental design was randomized blocks in a 2x3 factorial with four replications. The treatment for this test were two settings (with and without the adjustment of the angles of the nozzles ) and tree application volumes 273, 699 and 954 L ha-¹.The study was conducted in an orchard of dwarf cashew, with eight years of age. It was concluded that the volumetric distribution profile showed better vertical distribution uniformity when the angles of the nozzles were regulated for the canopy, the adjustment of the angles of the nozzles for the canopy provided greater deposition of droplets, the increased volume of application resulted in higher depositions in the leaves of the crop.

The phytopathological condition of the vineyard and the reduction in the use of crop protection products are closely linked to the efficiency of the use of sprayers. The objective of the work was to identify the best operative conditions to improve the canopy coverage of the spraying. From 2012 to 2017 173 field trials were carried out in 40 farms, on 24 varieties, testing 72 different sprayers in North Eastern Italy. Water-sensitive papers of 2.5 × 2.5 cm were positioned in eight points in the vine canopy according to a standardized method, and they were examined after spraying for spray deposition. In general, results showed that coverage of the lower leaf surface was very poor. On the contrary, the upper section of leaves in the outer canopy layers have received excessive spraying, over 70% coverage in 25% of cases. The coverage uniformity was improved by using driving speeds lower than 6 km / h and using upward air flow direction.

Abstract. Efficient chemical spray applications are vital to reduce off-target drift, economic losses to tree fruit growers, and negative environmental impacts. It is thus important to adequately calibrate and adjust orchard sprayers for intended applications. This technical note describes the design, prototyping, and field evaluation of a sensor-based smart spray analytical system (SSAS). The SSAS is equipped with units for spray capturing and volumetric quantification, air-assist velocity measurement, system actuation and control, and data acquisition and wireless transmission. The spray liquid and air-assist velocity quantification units are assembled on a custom-made mobile frame for vertical stop-and-go movement to provide measurements at eight distinct sampling heights above ground level. The data acquisition and transmission units autonomously log the data on-board and transmit wirelessly to a receiving computer with time and height stamps for real-time graphical visualization. All these autonomous processes are guided by a custom programmable single-board computer. The SSAS was preliminarily evaluated for spray liquid and air-assist velocity pattern assessment of an air-assisted orchard sprayer in four sets of spray trials. An average spray liquid recovery of 14.03% and pertinent coefficient of variation (CV) of 10.73% were observed. An average CV of 11.93% was observed in the air-assist velocity patterns. Overall, the SSAS provided measurements within acceptable ranges of variation. This system can thus minimize the experimental errors, time, and efforts involved in conventional assessments of sprayer attributes, thereby providing a reliable solution for orchard sprayer calibration and adjustment. Keywords: Air-assist velocity pattern, Airblast sprayer calibration, Data storage and transmission, Graphical visualization, Smart spray analytical system, Spray liquid pattern.

Highlights Intelligent sprayers require crop canopy-specific base spray rate (SR) adjustments. SRs can be estimated by Tree Row Volume (TRV) and Unit Canopy Row (UCR) methods. This study formulated TRV and UCR based SRs for modern apple orchard canopies. Field trials evaluated spray deposition and coverage variations for these rates. TRV and UCR based treatments had comparable spray performance to the grower-adapted application rate. Abstract. The efficiency of air-assisted sprayer-based chemical applications in horticultural crops is dependent on several factors, including that of the application rate as the amount of liquid per ground area (L ha-1 or gal acre-1 [GPA]). In contrast to the conventional GPA-based application rates, recently developed intelligent and precision sprayers use the input spray rate (SR) as the amount of liquid volume (L) required to spray one cubic meter of crop canopy (L m-3 or ounces per cubic foot). This input rate ranges between 0.06 and 0.13 L m-3 depending on the architecture and canopy size. However, the exact value of input SR is decided based on grower experience and manufacturer recommendation and can often be a broad estimation. Therefore, this study was conducted to explore methods that could be used to have a precise estimate of the input SR related to the canopy being sprayed for optimal spray applications. Tree row volume (TRV) and unit canopy row (UCR) methods were used to estimate input SRs and the sprayer field efficiency was evaluated in a vertical fruiting wall-trained commercial apple orchard, typical in the State of Washington, USA. Field spray trials were conducted in the full canopy growth stage, spraying a mix of fluorescent tracer dye of 2 g L-1 concentration at a calibration speed of 1.50 m s-1. Spray deposition and coverage were evaluated in replicated field trials using deposit samplers (mylar cards and screen) and water-sensitive papers, respectively. Test results demonstrated that both TRV (SR: 0.09 L m-3) and UCR (SR: 0.10 L m-3) were effective methods to calculate the spray rates since their spray deposition and coverage were comparable to that of the grower-adapted application rate (935 L ha-1). While the spray rates calculated by both methods provided better application efficiency, an SR of 0.09 L m-3 calculated by the TRV method would be preferable in spray applications of fully foliated fruiting wall-trained apple trees as it sprayed less liquid. Although the TRV method could potentially be applicable for estimating SR with an adjustment factor to compensate for the pruning level, crop-specific further evaluations are suggested for different canopy training systems. Keywords: Intelligent sprayer, Modern orchard systems, Spray rate, Tree row volume, Unit canopy row.

Abstract Spray coverage may influence the efficacy of insecticides targeting the invasive vinegar fly Drosophila suzukii (Matsumura), a primary pest of raspberries and blackberries. In commercially managed caneberries, spray coverage is typically lowest in the inner and lower plant canopy, regions that overlap with higher levels of adult D. suzukii activity. To understand how spray coverage of fruit impacts efficacy against D. suzukii, laboratory bioassays were conducted using raspberries. In laboratory bioassays, higher spray coverage did not impact larval infestation rates but did increase adult mortality, indicating that flies can avoid a lethal dose of insecticide when applications do not achieve adequate coverage. We also evaluated how carrier water volume impacts spray coverage patterns throughout the canopy of raspberry and blackberry plants using both airblast and CO2 backpack sprayers. Increasing carrier water volume generally improved spray coverage in the lower plant canopy. However, effects in the upper plant canopy were inconsistent and varied between sprayer types. In addition to carrier water volume, other approaches, including adjusting the pesticide sprayer equipment used and/or sprayer calibration, should also be explored to improve coverage. Growers should evaluate spray coverage in their caneberries to identify and troubleshoot coverage issues. Results from this study indicate that taking the time to optimize this aspect of pesticide application may improve chemical management of D. suzukii and will likely also improve control of other important caneberry pests.