Comparative assessment of agro-environmental performance of vineyard sprayers using a physical full scale model of a vineyard row

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]INSPIRE

International audience

anglais. National policies in Europe aim to reduce use of pesticides. Grapevine receives yearly many sprayings. There is a great variety of sprayers available for vineyards. We can sum up ques-tions addressed to research bodies by the following issues. Is it possible to sort out sprayers and practices according to crop protection and environmental performances? How much is it possible to save on amounts of chemicals sprayed when one uses an efficient sprayer? The present contribution to this research is based on a 4 rows, 10 meters length, physical full scale model of a vineyard. The Evasprayviti model of a vineyard row was designed to repro-duce different foliage volume and densities and to simulate the interaction of the canopy with the flow of plant protection product and air emitted by a mobile sprayer. It comprises a col-lecting device, and a complementary structure on each side of it. The collecting device ena-bles accurate and repeatable sampling of the spray deposits. It is composed of plastic sheets that simulate leaves, attached to vertical aluminium posts. The complementary structure pre-vents perturbative effects on the spray flow on the edges of the collecting device. Evasprayviti can be configured to simulate different growth stages (Codis&al, 2013). The test spray is a mix of a tracer, Tartrazine, and water. A standard pneumatic sprayer, an airblast sprayer and an air-assisted face to face sprayer were tested. The pneumatic sprayer was tested in 3 configurations, for spraying respectively 2, 3 and 4 rows at a time. The face to face sprayer and the airblast sprayer were configured to be used to spray 3 rows and 2 rows, respectively. The amount of product deposited in the canopy and its distribution according to depth and height of leaves was studied for early, intermediate and full growth stage, with respective Leaf Area Index (LAI) values of 0.24, 0.88 and 1.68 ha/ha. The sampling of a cross-section of the collecting device was divided in compartments (3 depths x 3 heights at full growth stage). Deposits on rows close to sprayer and on rows next to sprayer were compared when relevant. The mass of deposits per unit of leaf surface, normalised by amount sprayed per hectare of ground, was measured for each compartment. For precision assessment, this normalised deposit was divided by the reference potential deposit on the target, which is cal-culated for each growth stage according to the hypothesis that all the spray is homogeneous-ly deposited in the compartments. Results showed different deposition profiles, which are discussed. The face to face sprayer exhibited the best efficiency and homogeneity in full and intermediate growth stage, and best efficiency on early stage as well, with homogeneity comparable to the pneumatic sprayer's on this stage. The airblast sprayer used on two rows had a good overall efficiency for early and intermediate stages but a bad homogeneity at all stages.