Spray technology for deposition of droplets on coffee leaves and fruits

Abstract

The correct deposition of spray along the canopy is important for the phytosanitary control in coffee plants; however, the structure of the plant makes this distribution difficult. This study aimed to evaluate the deposition of a tracer on leaves and fruits in coffee cultivation, with respect to the application rate and type of hydraulic nozzle, as well as the use of an electrostatic spraying system. A hydropneumatic sprayer was used, with hydraulic nozzles of empty conical jet of the series TVI (coarse droplets with air induction) or JA (fine droplets), at rates of 200 and 400 L ha-1. An electrostatic system, with SPE-2 nozzle and rate of 200 L ha-1, was also evaluated. The deposition of the tracer on leaves and fruits of the upper, middle and lower thirds of the trees, as well as the losses to the ground in the canopy projection, were quantified using spectrophotometry. The results indicated that the electrostatic application provides a greater deposition on leaves of the upper third than the hydropneumatic application, regardless of the application rate. The use of the TVI nozzle results in a greater deposition on the fruits of the middle third and a greater loss to the ground than the JA nozzle. Although an application rate of 400 L ha-1 results in a greater deposition on the fruits of the middle third than an application rate of 200 L ha-1, it also causes a greater loss to the ground.

KEYWORDS: Coffea arabica, hydraulic nozzles, hydropneumatic sprayer.