Design and Development of a Rose Plant Disease-Detection and Site-Specific Spraying System based on a Combination of Infrared and Visible Images

Rose, as one of the oldest flowers in cultivation and the most popular of all cut flowers throughout the world, is susceptible to several diseases. Powdery mildew and gray mold are two of the most common diseases in the greenhouse cultivation of roses. Changes in plant leaf temperature mainly resulting from changes in transpiration in response to such stresses as pathogen infection, water stress, or physiological changes can be monitored instantly and remotely by thermographic imaging. In this research, a smart detection and spraying system was designed and developed to recognize rose powdery mildew and gray mold diseases using a combination of thermal and visible images. The system consists of a thermal camera and a visual camera both mounted on a C-shaped carriage. The carriage is capable of moving along plant rows and rotating around each rose shrub. In addition, a site-specific sprayer was designed that consisted of an electrically-actuated pneumatic directional valve, a pneumatically-actuated directional valve, a pressure regulator, a pressure tank, a compressor, a manual flow control valve, and a nozzle. Droplets volume median diameter, percent of coverage, and system performance in spraying the specified positions were evaluated. Analysis of the pre- and post-spray thermal images showed that such index as temperature median can be successfully exploited to determine spray coverage and uniformity.