Efficacy of glyphosate applied using an electrostatic sprayer as affected by adjuvant and carrier volumes

The activity and efficacy of glyphosate as a post-emergence herbicide can be affected by several factors, such as the environmental conditions during application, the post-application period without precipitation, stage of weed development, the use of adjuvants, and water quality (Dan et al., 2009). Law (2001) demonstrated that the electrostatic force exceeds the gravitational force by 51 times for droplets with 30 µm diameter, and 14 and 4 times for droplets with 100 and 300 µm diameters, respectively. [...]the droplet size is particularly important in this system. (2002) observed that an increase in induction voltage increases the magnitude of the droplet charge to an extent where the voltage can damage the electrification of droplets and the quality of the application. [...]the objective of the present study was to evaluate the use of electrostatic spray technology in the deposition, drift, and chemical control of weeds, with glyphosate as a function of adjuvant concentration and application rates. 2 Materials and Methods 2.1 Experimental area, treatments, and application The field experiment was carried out at 842 m of altitude, in an area with flat topography and Aw type climate (humid, tropical with dry winter) (Beck et al., 2018). According to the manufacturers, the SPE 1 tip, operating at 300 kPa, has a flow rate of 0.26 L min-1 and a volume median diameter (VMD) of 125 µm, and the AIXR 11002 tip, working at 300 kPa, has a flow rate of 0.79 L min-1 and a VMD of 332 µm. Before herbicide application, the weeds in the area were estimated.