Ensure that the spray rig is calibrated accurately and frequently. Calibration and maintenance should be undertaken regularly and include checks of nozzle performance and wear, pressure, the accurate working of gauges and regulators, spray output, filters, and the speed of ground rigs. To minimise spray drift it is necessary to monitor weather conditions during and immediately after application. Without access to real-time weather information in the vicinity of the target crop, aerial and ground based spraying should not be undertaken. Ideally, relative humidity should be high and temperature not greater than recommended for the product.
Temperature affects the rate of evaporation, particularly water based sprays.
Evaporation can reduce the size of droplets making them more drift prone. ULV formulations, which rely on light oil as a carrier, are less prone to evaporation. High relative humidity is preferable to minimise drift that can occur through evaporation. Applications at temperatures above 30 o C and at relative humidities below 45 o C increase the risk of drift. Ensure that spraying is done in cross-wind conditions rather than directly into or with the breeze.