2017 ASHS Annual Conference

Advancing conventional sprayer technology with precision variable-rate capability is an economically feasible method to solve current challenges associated with imprecise application and extensive waste of foliar-applied pesticides and other products. A concept-proven laser-guided intelligent sprayer was previously developed to adjust spray outputs based on tree canopy architectures in real time. The sprayer could apply different rates to different sections of individual plants. On-farm field tests in commercial nurseries demonstrated the pest control efficacies of this experimental intelligent sprayer were comparable to those of conventional sprayers, while the new sprayer reduced average pesticide use by 46% to 70%, reduced airborne spray drift by up to 87%, and reduced spray loss on the ground by 70% to 90%. Recently a versatile laser-guided spray control system was developed as a retrofit for most orchard air-blast sprayers currently used in ornamental nurseries, apple, peach and pecan orchards, small fruit plantings, vineyards and other specialty crops. The retrofit modified the control system previously developed for the concept-proven prototype sprayer. The critical components of the new control system were the algorithm and control circuits integrating with a high-speed laser scanning sensor, a non-contact Doppler radar travel speed sensor, a two-microprocessor manipulated nozzle flow rate controller, an embedded computer and inputs of particular sprayer parameters. The control system was able to determine the presence of a tree canopy, map the canopy structure, estimate the foliage density, calculate the sectional canopy volume and spray volume designated to individual nozzles, and manage variable numbers of nozzles to discharge variable spray outputs to match tree architectures. Laboratory tests were conducted to validate the control system functions and capabilities. These tests included automatic control of individual nozzles, separate groups of nozzles and random numbers of nozzles by changing target positions; determination of delay times to accommodate different sized sprayers by changing laser sensor positions and travel speeds; and manual selection of active nozzles to discharge sprays to desired target heights. Test results demonstrated that conventional sprayers with the retrofitted control system were able to characterize the presence, size, shape, and foliage density of target tree canopies, measure sprayer travel speed, and then automatically control spray outputs of each individual nozzle to match canopy architectures in real time. This new spray control system will significantly advance conventional spray technologies and offer an environmentally responsible approach to controlling insects and diseases and applying other foliar products for specialty crop production.