Unoccupied Aerial Systems-based Disease Assessments of Specialty Crops: Case Studies of Broccoli, Turnip Seed, and Hemp Crops

Disease detection through traditional techniques such as scouting fields on foot, molecular assays, or morphological identification of plant pathogens is time-consuming and costly. Scouting for disease in the field can be extremely subjective and largely depends on the scout’s experience and knowledge of pathogen identification. Unoccupied aerial systems-based remote sensing on specialty crops has the potential to save labor, enable earlier detection of plant biotic stress and abiotic stress, and allow easier access to fields during wet conditions. For simple measurements, such as canopy cover, remote sensing works well; however, more sophisticated measurements of plant health involve complex data processing and may be challenging to implement. The difficulty is compounded for plant–pest pairs that have no published literature about remote sensing to reference. Technological improvements are steadily advancing, but these advances have led to short-term obsolescence, which remains an obstacle in the development of remote-sensing programs. Case studies of the following three different fungal diseases important in western Oregon crop production are presented: Alternaria black spot on broccoli, black leg on turnip, and gray mold on hemp. Remote sensing technologies present an objective approach to sampling that can address many concerns associated with traditional field sampling. These techniques can serve as a viable alternative that facilitate the development of more insightful integrated pest management programs that are essential for future agricultural efficiency.