Electrostatic Ground-Rig Spraying: An Overview

Contact, induction, and corona electrostatic charging systems for pesticide spraying are reviewed and are compared with uncharged spraying systems. When uncharged sprays are poorly intercepted by plants, charging significantly increases deposition, drawing from the reservoir normally deposited on the soil. Post-emergent herbicide spraying is the one area where the benefits of electrostatic charging are identified least easily. For insecticides and fungicides where the young crop is the ‘general’ target, increased capture of charged spray may permit reducing doses with economic and environmental benefits. While charging may not increase total capture where uncharged spray interception is good, it does alter spray distribution throughout the crop canopy. The biological consequences of modifying spray distribution depend upon the ‘real’ pesticide target. In situations where the crop acts as an electrical shield limiting spray penetraton, air assistance is necessary to augment charged spray deposition within the crop canopy. Drift of charged spray clouds should be related to drop spectra, velocities and trajectories and requires further study as do protocols for spray charge measurement and definition. In addition to biological performance, the transfer of electrostatic technology to farms is limited because of financial, legal, and practical factors. Identifying specific major crop/pest problems will help to introduce electrostatic spraying, which will complement, rather than replace, traditional spray systems.