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Oral: Schroth Faces of the Future Symposium: Epidemiology and Management


Monitoring spread of Phymatotrichopsis root rot disease in alfalfa fields using aerial imagery
C. MATTUPALLI (1), C. Moffet (2), J. Rogers (1), C. Young (1) (1) The Samuel Roberts Noble Foundation, U.S.A.; (2) USDA-ARS, U.S.A.

Phymatotrichopsis Root Rot (PRR) caused by the soil-borne ascomycete, Phymatotrichopsis omnivora affects alfalfa stand life. PRR disease typically manifests as circular rings and continuous monitoring of PRR disease sites is essential from a disease management perspective. In summer 2014, an Unmanned Aerial Vehicle (UAV) was utilized to take aerial images of a 48.5 hectare alfalfa hay production field at the Noble Foundation’s Red River Farm, Burneyville, OK. The UAV imagery was obtained using a 10 megapixel (MP) RGB (Red/Green/Blue) and 10 MP Near Infrared dual sensor camera mounted on a Vireo UAV. In autumn 2014 and during the 2015 growing season, Very Large Scale Aerial (VLSA) digital imagery was obtained using a 22 MP Canon EOS 5D Mark III mounted on a Dragonfly sport utility aircraft. Images were taken at approximately monthly intervals starting in June and continuing through October during both years. Aerial imagery was validated at monthly intervals in 2015 across five active disease sites by measuring the movement of the disease front at ground level. By the end of the growing seasons, considerable agreement between UAV and ground data was observed for PRR disease front movement. This movement ranged from 2.8 m for the acquired aerial images and 3.0 m for ground-based observations. Results from this study show the feasibility of UAVs as a tool for tracking disease spread throughout the growing season.