2018 ASHS Annual Conference

Citrus diseases, like Huanglongbing (HLB) and Phytophthora, are challenging to citrus growers in the Lower Rio Grande Valley (LRGV) due to their impacts on yield and production. These diseases are associated with symptoms and physiological changes which can be evaluated through field measurements to help quantify their impacts on tree health. Nonetheless, physiological measurements, such as tracking crop physiological stages, health status, disease progression, and yield potential, can be difficult to determine due to environmental factors, inaccessibility, etc. To address this concern, unmanned aerial systems (UAS) have recently been introduced as an innovative way to monitor crop growth and production factors. Current UAS research has focused on a graphical display using near infrared (NIR) cameras to determine tree health. While this has had promising success in tree evaluation and health assessment, equipment and cameras are cost prohibitive to many growers. One less expensive alternative is red/green/blue (RGB) or true color imaging, for remote sensing and crop evaluation. True color images can provide farmers with data that is informational and practical for monitoring citrus trees. To assess its feasibility in tree evaluation, we will fly a DJI Phantom 4 Pro Quadco aircraft with a RGB camera every 4 months in 2017 and 2018. The objective is to determine if true color images can provide accurate data on citrus health using less expensive and labor intensive methods. Preliminary assessments of tree health in a HLB affected field of Rio Red grapefruit trees on three different rootstocks indicate that HLB distribution varies by location and rootstock. Of the rootstocks surveyed, trees on C146 rootstocks had a lower incidence of Phytophthora infection and HLB + Phytopthora infection. Additionally, the percentage of healthy trees was highest in trees on C146 rootstocks followed by trees on C22 rootstocks and C57 rootstocks. UAS images have been collected and are currently being processed for correlation with these field findings.