Ultrasonic sensors were originally designed to measure distances in industrial environments, where objects are rigid, and the reflection surface is perpendicular to the direction of the ultrasonic wave; therefore, some authors question their usefulness in orchards [6]. Despite these shortcomings, ultrasound sensors are currently being used for the characterization of plant mass and provide good results in certain scenarios. The main advantages of ultrasonic sensors are their robustness and low price. Contrary to the expensive radar system, Gil et al. [7] suggested the use of ultrasonic sensors and proportional electro-valves with the corresponding software and automation, which allowed real time modification of the sprayed flow rate adapted to the crop structure of the vineyard.McConnell et al. [8] estimated canopy volume by using several ultrasonic sensors mounted on a vertical mast or on a sprayer things driven by a tractor, but the application technologies did not allow this information to be used in real time. Gil et al. [7] evaluated a modified orchard air-blast sprayer equipped with three ultrasonic transducers and concluded that savings in pesticide application when using the electronic control system were strongly related to target crop architecture. The same authors found that sprayer control based on target measurement resulted in substantial increases in savings on applied spray liquid.Molt�� et al. [9] also applied three ultrasonic sensors for the detection and ranging of geometric information from citrus fruit tree canopies; this enables the application of pesticides in fruit orchards by three different flow rates according to a canopy width estimation made with an ultrasonic sensor. In response to changes in the shape and size of the vines during the growing season Gil et al. [7] reported a reduction in spray volume and use of pesticides by up to 57%, while coverage and penetration rates were similar to those from conventional spraying methods. Llorens et al. [10] achieved a 58% saving in application volume with the variable rate method, obtaining similar or even better leaf deposits in comparison to the control with an air-blast orchard sprayer. Tumbo et al. [11] used ultrasonic sensors to estimate the most relevant geometrical parameters of trees and tree crops i.e., height, width, volume and leaf area and compared these with manual measurements. In [12] the variability in distance estimations in an apple orchard proved to cause interference by sensors whenever these were mounted too close each other; thus it was suggested that sensors be separated more than 60 cm apart in order to avoid high interference effects. In [13] the effect of foliage density and tractor speed on ultrasound measurements was investigated. The software developed to create maps of volume in real time showed the influence of row spacing and age on the accuracy of tree volume measurements.