Evaluation of the effect of spray pressure in hand-held sprayers in a greenhouse tomato crop

In greenhouses, plant-protection products are usually applied by hand-held high-pressure spray guns or lances spraying at high volume rates. This low-technology equipment produces a deposit distribution of low uniformity on the plant canopy, heavy losses to the soil, and high exposure risk to workers. The aim of the present work was to evaluate the effect of spray pressure on deposition and losses to the ground using a hand-held spray lance in a greenhouse tomato crop. Spray applications were made at three different pressures (1000 kPa, 1500 kPa and 2000 kPa) in two developmental stages of a tomato crop. The results show that for the applications at the highest pressure, the average deposit was between 22.5% and 34.6% less than at the two lower pressures. Also, the use of high pressures such as 2000 kPa hampered penetration into the plant canopy, with deposition values in the inner zones of the canopy of between 9.4% and 37.4% less than when pressures of 1000 kPa and 1500 kPa were used. Nevertheless, the losses to the ground for the highest pressure were between 10.3% and 24% lower than for the two lower pressures.