Search

An orchard sprayer prototype running a variable-rate algorithm to adapt the spray volume to the canopy characteristics (dimensions, shape and leaf density) in real-time was designed and implemented. The developed machine was able to modify the application rate by using an algorithm based on the tree row volume, in combination with a newly coefficient defined as Density Factor (Df). Variations in the canopy characteristics along the row crop were electronically measured using six ultrasonic sensors (three per sprayer side). These differences in foliage structure were used to adjust the flow rate of the nozzles by merging the ultrasonic sensors data and the forward speed information received from the on-board GNSS. A set of motor-valves was used to regulate the final amount of sprayed liquid. Laboratory and field tests using artificial canopy were arranged to calibrate and select the optimal ultrasonic sensor configuration (width beam and signal pre-processing method) that best described the physical canopy properties. Results indicated that the sensor setup with a medium beam width offered the most appropriate characterization of trees in terms of width and Df. The experimental sprayer was also able to calculate the application rate automatically depending on changes on target trees. In general, the motor valves demonstrated adequate capability to supply and control the required liquid pressure at all times, mainly when spraying in a range between 4.0 and 14.0 MPa. Further work is required on the equipment, such as designing field efficiency tests for the sprayer or refining the accuracy of Df. [ABSTRACT FROM AUTHOR]

New spraying systems embedded with different technologies have been developed for pesticide application in 3D crops. However, while applied to specific tree crops, the potential spray drift mitigation for advanced spraying systems needs to be classified due to the great variability of spray equipment and canopy structure. Here a precision spraying system was developed and compared with two typical spraying systems (conventional system, optimized system following the best management practices) for the applied volume/pesticide and spray drift in an apple orchard at two growth stages following the ISO22866-2005 protocol. Compared to the conventional system, the other two advanced systems significantly reduced the amount of ground drift (> 60%) at most of the sampling distances at the growth stage BBCH 72, while the precision system demonstrated the best drift mitigation (57.3% reduction) at the stage BBCH 99. For the airborne drift, a remarkable drift reduction was also achieved with the two advanced systems. Specifically, the optimized spraying system exhibited a drift reduction by approximately 80% at the first growth stage, and the precision application demonstrated its considerable advantages in minimizing drift loss for the sparse canopy at the stage BBCH 99. Moreover, the saving of applied volume/pesticide was achieved by 12% with the optimized system and 43% with the precision system. This study revealed the necessity and prospect of the advanced spraying systems to reduce the environmental contamination and health risk from pesticide applications in fruit tree production. [ABSTRACT FROM AUTHOR]

An orchard variable-rate sprayer applies the appropriate amount of plant protection products only where they are needed based on detection data from advanced sensors, a system that has attracted increasing attention. The latest developments in the detection unit, variable control unit, and signal-processing algorithm of the variable-rate sprayer are discussed. The detection of target position and volume is realized with an ultrasonic sensor, a laser scanning sensor, or other methods. The technology of real-time acquisition of foliage density, plant diseases and pests and their severity, as well as meteorological parameters needs further improvements. Among the three variable-flow-rate control units, pulse width modulation was the most widely used, followed by pressure-based, and variable concentration, which is preliminarily verified in the laboratory. The variable air supply control unit is tested both in the laboratory and in field experiments. The tree-row-volume model, the leaf-wall-area model, and the continuous application mode are widely used algorithms. Advanced research on a variable-rate sprayer is analyzed and future prospects are pointed out. A laser-based variable-rate intelligent sprayer equipped with pulse width modulation solenoid valves to tune spray outputs in real time based on target structures may have the potential to be successfully adopted by growers on a large scale in the foreseeable future. It will be a future research direction to develop an intelligent multi-sensor-fusion variable-rate sprayer based on target crop characteristics, plant diseases and pests and their severity, as well as meteorological conditions while achieving multi-variable control. [ABSTRACT FROM AUTHOR]

Site-specific management of crops represents an important improvement in terms of efficiency and efficacy of the different labours, and its implementation has experienced a large development in the last decades, especially for field crops. The particular case of the spray application process for what are called "specialty crops" (vineyard, orchard fruits, citrus, olive trees, etc.) represents one of the most controversial and influential actions directly related with economical, technical, and environmental aspects. This study was conducted with the main objective to find possible correlations between data obtained from remote sensing technology and the actual canopy characteristics. The potential correlation will be the starting point to develop a variable rate application technology based on prescription maps previously developed. An unmanned aerial vehicle (UAV) equipped with a multispectral camera was used to obtain data to build a canopy vigour map of an entire parcel. By applying the specific software DOSAVIÑA®, the canopy map was then transformed into a practical prescription map, which was uploaded into the dedicated software embedded in the sprayer. Adding to this information precise georeferenced placement of the sprayer, the system was able to modify the working parameters (pressure) in real time in order to follow the prescription map. The results indicate that site-specific management for spray application in vineyards result in a 45% reduction of application rate when compared with conventional spray application. This fact leads to a equivalent reduction of the amount of pesticide when concentration is maintained constant, showing once more that new technologies can help to achieve the goal of the European legislative network of safe use of pesticides. [ABSTRACT FROM AUTHOR]

Electrostatic sprayers can be an option for increasing the effectiveness of treatments and reducing pesticide consumption, but it still requires more verifications, especially in orchards. The spray deposition performances of three different electrostatic sprayers design were compared for apple tree pesticide application, all of them used with the electrostatic system activated and disactivated, as conventional spray application. Despite designs of particular type sprayers were unique, no significant differences were observed in the normalized deposition and droplets density between the conventional and electrostatic spray methods of the same sprayer, but differences were found between the vertical boom and the pneumatic sprayer in terms of coverage. The normalized deposition values of the three sprayers were very similar, ranging between 1.0 and 1.5 μg cm−2. However, the vertical boom sprayer produced the highest spray coverage, followed by the multi-fan sprayer. In general, the measured values of coverage and deposit obtained were in the three cases similar, independently on the use or not of the electrostatic device, being the sprayer type more affecting parameter rather than the electrostatic charging system. Differences in spray deposition qualities on apple trees were observed among three types of sprayers, but were not for the same sprayer with and without activation of the electrostatic charging system. Appropriate design of orchard sprayers according to the canopy structure seems to be more effective rather than the implementation of electrostatic spray charge system to achieve the European challenge of 50% reduction of pesticides by 2030. [Display omitted] • There is an European objective of 50% reduction of PPP by 2030. • Spray patterns for three electrostatic airblast sprayers were characterized. • Depositions on apple trees were assessed by using the electrostatic system or not. • No significant differences were found for normalized deposition. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, LIDAR (light detection and ranging) sensors have been widely used to measure environmental parameters such as the structural characteristics of trees, crops and forests. Knowledge of the structural characteristics of plants has a high scientific value due to their influence in many biophysical processes including, photosynthesis, growth, CO2-sequestration and evapotranspiration, playing a key role in the exchange of matter and energy between plants and the atmosphere, and affecting terrestrial, above-ground, carbon storage. In this work, we report the use of a 2D LIDAR scanner in agriculture to obtain three-dimensional (3D) structural characteristics of plants. LIDAR allows fast, non-destructive measurement of the 3D structure of vegetation (geometry, size, height, cross-section, etc.). LIDAR provides a 3D cloud of points, which is easily visualized with Computer Aided Design software. Three-dimensional, high density data are uniquely valuable for the qualitative and quantitative study of the geometric parameters of plants. Results are demonstrated in fruit and citrus orchards and vineyards, leading to the conclusion that the LIDAR system is able to measure the geometric characteristics of plants with sufficient precision for most agriculture applications. The developed system made it possible to obtain 3D digitalized images of crops, from which a large amount of plant information – such as height, width, volume, leaf area index and leaf area density – could be obtained. There was a great degree of concordance between the physical dimensions, shape and global appearance of the 3D digital plant structure and the real plants, revealing the coherence of the 3D tree model obtained from the developed system with respect to the real structure. For some selected trees, the correlation coefficient obtained between manually measured volumes and those obtained from the 3D LIDAR models was as high as 0.976. [Copyright &y& Elsevier]