Ground-Based Spectral Reflectance Measurements for Efficacy Evaluation of Aerially Applied Glyphosate Treatments

Abstract. Aerial application of herbicides is a common tool in agricultural field management. The objective of this study was to evaluate the efficacy of glyphosate herbicide applied aerially with both conventional and emerging aerial nozzle technologies. A Texas A&M University Plantation weed field was set up in a randomized complete block design with three replicates. Four aerial spray technologies treatments: electrostatically- charged nozzles powered off, electrostatically charged nozzles powered on, conventional flat-fan hydraulic nozzle and rotary atomizers were tested. Spectral reflectance measurements were acquired with a ground-based sensing system for all treatment plots to evaluate glyphosate efficacy and performance of aerial spray technologies. Field measurements were carried out at 1, 8, and 17 days after treatment (DAT). Statistical analyses indicated that glyphosate applied with different methods killed the weeds effectively compared to untreated areas at 17 DAT. Electrostatically-charged nozzles powered on, conventional flat fan nozzles and rotary atomizers had better performance than the electrostaticly charged nozzles powered off. The results provide applicators with guidance for aerial application equipment setups that can result in herbicide savings and optimized applications in other crop.

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