No abstract

A summary is given of research within the field of application technology for crop protection products for the past 10 years in The Netherlands. Results are presented for greenhouse, orchard, nursery tree and arable field spraying for the typical Dutch situation. Research predominantly focussed on the quantification of spray deposition in crop canopy and the emissions into the environment, especially spray drift. The risk of spray drift is related to defined distances and dimensions of the surface water adjacent to a sprayed field. Spray deposition and spray drift research was setup in order to identify and quantify drift-reducing technologies. Results are presented for cross-flow sprayers, tunnel sprayers and air-assisted field sprayers. For field crop spraying with a boom sprayer the effect of nozzle type on spray deposition in crop canopy and spray drift is highlighted both with a modelling approach as based on field experiments. The use of spray drift data in regulation is discussed. A relation between spray deposition and biological efficacy is outlined for drift-reducing spray techniques. The effect of spray drift-reducing technologies in combination with crop-and spray-free buffer zones is outlined. It is concluded that spray technology plays an important role to minimise spray-and crop-free buffer zones, and to maintain biological efficacy and acceptable levels of ecotoxicological risk in the surface water.

No abstract

In an experimental greenhouse, growing a tomato crop, it was investigated if a reduction in spray pressure could improve the spray result, while, simultaneously, emission to the ground could be reduced. Spray deposition on the leaves and the emission to the ground was evaluated at different spray pressures (2.5, 5, 10 and 15 bar). An Empas vertical spray mast with 6x2 Teejet XR8002VK flat fan nozzles was used to spray the tomato crop in three stages of crop growth, respectively 0.75, 2.25 and 2.80 m height, spraying 500-1500 l ha-1 (stage 1) and 1000-3000 l ha-1 (stage 2 and 3) depending on the spray pressure. Flow rate ranged from 0.74 to 1.80 l min-1 at an increasing spray pressure from 2.5 to 15 bar. The VMD (Volume Median Diameter) decreased in the same pressure range from 207 to 124 µm. The emission of spray liquid to the ground was measured in the spraying path and beneath the plants between the rows closest to the spray mast. The highest emission to the ground appeared closest to the spray mast, and increased at higher spray pressures. In crop growth stage 1 and 2 about 35% of the spray volume emitted to the ground, in stage 3 only 15%. The direction of the nozzles (upwards directed with an angle of at least 40 0) appeared to be of great importance. The deposition of spray liquid on the leaves was measured at two rows (A: closest to the sprayer, B: the next row behind it) at one, two or three heights depending the stage of the crop. Highest spray deposition could be found in row A, at the upper side of the leaf and at a higher working pressure. Differences were smaller in the next row and at greater height in the plant. Finally it could be concluded that a decrease in spray pressure to 5 bar gave an adequate deposition on the leaves in µl cm-2 , and a decrease in emission to the ground.

No abstract