Design and development of air assisted intra canopy sprayer for cotton and pigeonpea

Uniform distribution and deposition of chemical application from top to bottom of plant canopy and on the undersides of the leaves is of utmost importance for effective control of pests. An intra canopy sprayer was designed consisting of nine nozzles to spray from top, middle and bottom to cover three rows for spraying where spray solution is so applied that it reaches to parts of the plant such as lower leaves, branches and stem to kill the pest at different stages of their life cycle. The developed sprayer was tested under laboratory conditions before going for field operations on cotton and pigeonpea. It was observed that the droplet size was decreased as the air velocity and operating pressure increased. The droplet size was bigger in the solid cone nozzle and smaller in the flat fan nozzle. The maximum droplet size was 232 μm by solid cone nozzle and minimum was 202 μm by hollow cone nozzle. Droplet density was increased with increase in air velocity and operating pressure. Droplet densities varied for different air velocities and operating pressures ranging from 74 to 138 drops cm⁻² for three different types of nozzles tested.