A New Technique for Informing the Cotton Replanting Decision

Suboptimal cotton stands are a common occurrence in cotton farming. The decision to replant these stands has long troubled farmers for many decades. The issue has intensified in recent years because most seed companies have increased the suggested retail price per bag of replanting seed by 25%. Jost et al. (2006) proposed that 50% or more of planted area occupied by skips of 3 ft or greater justifies replanting. This study, however, was conducted at a relatively small scale, and stands were measured using manual techniques which can lead to poor decision-making. Although recommendations by Jost et al. (2006) provide a good starting point to the cotton replanting justification, further studies should be conducted at larger scales with more advanced methods to detected plant skips with greater accuracy and precision. The goal of this study was to update current replanting recommendations using unmanned aerial vehicle (UAV) technology. The study was conducted at three sites in eastern North Carolina during the 2019 and 2020 growing seasons. Each site had an early and a late planted trial. Trials were subjected to a randomized complete block design composed of four-row plots and four replications. Treatment plots were produced using various ratios of DP 1646 and DP 493 cotton seed (100%, 75%, 50%, 25%, and a 100% simulated replanting treatment) and were planted at a rate of 43,560 sd/A. In 2020, a 10% treatment plot was added to the study. Immediately following emergence, glyphosate (32 oz/A) and glufosinate (42 oz/A) were applied to terminate all conventional seedlings and produce random skips of various size and frequency. Cotton skips were detected using a DJI Matrice 600 Pro equipped with a Zenmuse X5 RGB sensor. Yield was regressed to the percent of planted area occupied by skips greater than 3 ft for each trial.