Checking the distribution quality of agrochemicals in the vineyard through the use of field monitoring

In this paper we propose a method enabling to assess in the field the correct setting of the sprayer considering specific varietal characteristics and changes occurring in the canopy throughout the vegetative season. The general aim of the present work was to set up a methodology to check the pesticide distribution at the canopy level and its loss onto the ground. The work was based on field trials and simple analytical methods. Performances of a sprayer with a product recycling device (tunnel sprayer) and a pneumatic nebulizer were compared. A certain number of vine leaves were sampled before and after the application of the agrochemical. A copper-based product was used because its quantification is easy and inexpensive in relation to other pesticides. For a more objective evaluation of pesticide distribution, the canopy was divided in high canopy and low canopy. Each of the two was sub-divided in inner canopy and outer canopy. Distribution homogeneity was determined using water-sensitive papers pinned to the upper page and lower page of vine leaves. The leaves sampled from different parts of the plants were washed with a solution of 1% nitric acid. The concentration of copper removed from the leaf surface was then quantified. In order to quantify the amount of product loss onto the ground, analytical measurements were performed along the treated rows and the adjacent ones. Results showed that the low and external part of the canopy was usually wetted easily, while a smaller amount of product was detected in the high, internal part, whereas the tunnel sprayer was able to lay on an amount of product which was 50% higher than the nebulizer. Moreover, the use of the tunnel sprayer allowed to reach a nearly homogeneous distribution on the two leaf pages, while some problems in wetting properly the lower page were denoted when the pneumatic nebulizer was used. The amount of pesticide lost onto the ground was observed to be also dependent upon the type of sprayer: the one provided with a product recycling device can limit the pesticide loss along the treated rows and especially in the adjacent ones