Rainfastness and adsorption of herbicides on hard surfaces

Authors

  • Pieter Spanoghe,

    Corresponding author
    1. Ghent University, Faculty Agricultural and Applied Biological Sciences, Department of Crop Protection Chemistry, Coupure Links 653, B-9000 Ghent, Belgium
    • FLTBW, Department of Crop Protection Chemistry, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
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  • Johan Claeys,

    1. KaHo St-Lieven, Campus Rabot, Department of Chemical Engineering, Gebroeders Desmetstraat 1, B-9000 Ghent, Belgium
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  • Luc Pinoy,

    1. KaHo St-Lieven, Campus Rabot, Department of Chemical Engineering, Gebroeders Desmetstraat 1, B-9000 Ghent, Belgium
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  • Walter Steurbaut

    1. Ghent University, Faculty Agricultural and Applied Biological Sciences, Department of Crop Protection Chemistry, Coupure Links 653, B-9000 Ghent, Belgium
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Abstract

Herbicides are still used to control weeds on hard surfaces, including municipal, private and industrial sites. Used under unfavourable conditions, especially when rain occurs shortly after application, herbicides may run off to surface waters. Such losses of herbicides from hard surfaces are estimated to be much higher than for herbicides used in arable fields. In this study, three kinds of hard surface were evaluated: asphalt, concrete surface and gravel (fine and coarse). Three herbicides were applied: glyphosate, diuron and diflufenican. Adsorption isotherms of diuron and diflufenican to the three surfaces were determined. At different times after treatment with the herbicides, rainfall was simulated by use of a rain-droplet spray nozzle, and the run-off was collected for analysis. After this run-off event, the materials were immersed in water to measure desorption which, together with the compound in the run-off, gave a measure of the dislodgable residues. The apolar herbicides diuron and especially diflufenican adsorbed strongly to asphalt. The polar herbicide glyphosate lost 75% in run-off from asphalt but was adsorbed strongly to soil and concrete pavement. Copyright © 2005 Society of Chemical Industry

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