IMPROVEMENT OF SPRAY RETENTION ON BARLEY LEAVES

摘要

The droplet size distribution of agricultural sprays is a key parameter during the plant protection product applications. Phenomena governing spray retention on plants are investigated for a very long time in order to optimise pesticide application. These can be divided in physical and chemical properties of either the target or the drop. Leaf morphology may play an important role in spray deposition. Different leaf structures such as wax, hairs, edges and veins are important impingement and retention variables. Surfactants are nowadays very useful additives to improve the effectiveness of phytosanitary treatments. They contribute to change the impact types and thus the amount of spray retained by the leaves of the treated plant.We performed tests of retention on whole barley plants on BBCH-scale 12 and small pieces of barley leaves at the same stage of growth. Spraying was done in three ways: water without surfactant, water with Break-Thru~R S240 and water with Li700*. The three slurries of fluorescein contained in an amount of 0.2 g / I. Fluorescein retained by the leaves in both cases is then measured by a spectrofluorometer. The retention tests on whole plants show that it is tripled by the first surfactant and doubled by the second. By cons on small pieces of barley leaves, the amount was increased by the use of surfactants but not to the same scale. This study concluded that the use of surfactants in spray pesticides may increase the amount of retention as a function ofleaf area and the surfactant used.