Aerial Electrostatic Spray Deposition and Canopy Penetration in Cotton

Spray deposition on abaxial and adaxial leaf surfaces along with canopy penetration are essential for insect control in cotton or for defoliation.  Electrostatically-charged sprays have shown promise for increasing deposition of sprays onto these surfaces.  For this study, 3 different aerial spray treatments were applied to late-season field cotton; electrostatic nozzles with charge off, electrostatic nozzles with charge on, and rotary atomizer nozzles.  There were 3 replications of each treatment. A daylight visible fluorescent dye was used as a tracer for the applied spray.  Twenty cotton leaves were collected from each treatment area (10 top canopy, 10 bottom canopy).  These leaves were then brought into the lab where the abaxial and adaxial leaf surfaces were digitally imaged under ultraviolet light and these images were then analyzed with image processing software to quantify spray droplets.  Leaf areas were measured with a leaf area meter.  The droplet density (drops/cm²) was then calculated for each leaf.  Treatments will be ranked based on highest droplet density both for top and bottom canopy.  The results presented herein will help aerial applicators choose the best application system for the job.