Journal of Agricultural Engineering

A study was conducted for efficient delivery of bio-pesticides for controlled spray application by selecting proper nozzles and operating parameters. The spray parameters of two different classes of bio-pesticides (bacterial-based Bacillus thuringiensis and fungal-based Beauveria bassiana) were evaluated for discharge by three different sizes of hollow cone nozzles (1.14, 2.31 and 3.56 mm in diameter) at four operating pressures (145, 245, 345 and 445 kPa). The discharge, spray width, cone angle, coefficient of uniformity (CU), volume median diameter (VMD), droplet volume fraction at 90 % (D_V0.9) and 10 % (D_V0.1), and span of water solution and two bio-pesticide solutions were measured. The results indicated that there was no significant difference in mean discharge, spray width and cone angle among water, bacterial-based bio-pesticide (BBP) and fungal-based bio-pesticide (FBP) solutions. But, these spray parameters for the selected solutions differed significantly (p<0.001) with different sizes of nozzles and operating pressures. There was significant difference (p<0.001) in CU when bio-pesticide was added to water. The type of spray solution, nozzle orifice diameter and pressure had significant effects (p<0.001) on mean VMD, D_V0.1 and span of spray. The means of solutions showed that the values of droplet spectra were highest for FBP solution, followed for BBP solution and water-only solution. It was concluded that the bio-pesticide solutions can be effectively sprayed with hollow cone nozzle having diameter of 3.56 mm at 145 kPa operating pressure.