Intelligent, Variable-rate Spray Technology Reduces Total Pesticide Output while Controlling Foliar Disease of Shumard Oak1

Abstract Air-blast sprayers have known inefficiencies in nursery production systems. Intelligent, variable-rate spray technology aims to improve application accuracy and reduce total pesticide consumption by utilizing pulse-width modulated solenoid valves, laser scanning and ground speed sensors, and a computerized algorithm to customize spray output based on plant presence, size, shape, and density. This study used an air-blast sprayer retrofitted with this variable-rate spray technology to directly compare spray characteristics and pest control of the sprayer operated in intelligent, variable-rate mode and conventional, constant-rate mode to spray trees grown in 57 L (15 gal) containers in a multi-row pot-in-pot production system. Variable-rate mode reduced total spray volume by 43% while providing equivalent, and at times better, disease control compared to the constant-rate mode for two fungal borne diseases of Shumard oak (Quercus shumardii Buckley). This research demonstrates the capability of variable-rate technology to reduce input costs, environmental harm, and risk of pesticide exposure while simultaneously controlling disease and maintaining saleable crops. Species used in this study: Shumard oak (Quercus shumardii Buckley).