Modernizing Cotton Replanting Recommendations Using UAV Imagery

When suboptimal plant stands occur, growers must decide if replanting is justified. Many factors influence these decisions including the costs of replanting, time left within the optimal planting window, prevailing temperatures and soil moisture, and the likelihood of improved success by replanting. Replanting is generally justified when 50% or more of the planted area is occupied by 3-foot “skips” between adjacent plants within a row. However, it is generally difficult to visually assess the percentage of planted area occupied by 3-foot skips, and very cumbersome and time-consuming to accurately measure. New advances in precision agriculture such as the implementation of unmanned aerial vehicles (UAV) and their ability to generate high-resolution imagery may allow for quicker and more precise assessments of planted areas. Research trials were conducted on three research stations in eastern North Carolina during 2019 to evaluate the utility of UAV technology for measuring skips. Treatments included transgenic and conventional seed mixtures of 75%, 50%, and 25% transgenic seed, which were compared to a standard treatment of 100% transgenic seed. Immediately following emergence, glyphosate and glufosinate were applied three times to terminate all conventional seedlings, leaving natural, random skips that varied in size and frequency. Using the data obtained through imagery, an algorithm was developed in R to measure distances between plants, which was compared to manual measurements of skips taken from 200 feet of row in each plot.