Etude des potentialités des systèmes d'application contrôlée des gouttes (CDA) pour les traitements phytosanitaires en céréaliculture (synthèse bibliographique)

Study of the potential for the use of controlled droplet application (CDA) upon cereal crops. A review. Introduction. Controlled droplet application (CDA) has the advantage both of the reduction in the span of droplet size distribution and in the volume of liquid applied, in comparison with conventional hydraulic nozzles. Literature. This review investigates the potential for the use of CDA relative to hydraulic nozzles within the early stages of weed control (2-3 leaves). The studies reviewed examine spray retention, linking the droplet characteristics (size, velocity and direction) of spray liquids with the architecture, density and wettability of the foliage. These studies show that the use of droplets of 300 µm, combined with an appropriate adjuvant and applied with a 60° forward-angled spray, led to the enhanced depositing of liquids on upright surfaces. Assessment of the reduced volumes applied by both application techniques was based on the mean, the variation coefficient and the deposition coverage. However, these results cannot be generalized, due to the different operative settings in which the spray application techniques were employed. Regarding the risk of drift to the side, the drift potential of droplets generated horizontally by CDA nozzles is greater than that of the conventional technique with a downward orientation of spray. The drift potential increases as the wind velocity increases and the volume median diameter (DV50) decreases. Conclusions. New settings of CDA nozzles in terms of DV50 and the direction of spray may address the challenge of precision agriculture. Innovative ways to apply pesticides, based on CDA, must be explored in order to avoid the sensitivity to wear of the teeth in spray applicators and to obtain a narrower droplet-size distribution.