Residues of Glyphosate in an Aquatic Environment after Control of Water Hyacinth (Eichhornia crassipes)

Abstract

Isopropylamine salt of glyphosate [N-(phosphonomethyl) glycine] was applied to control water hyacinth [Eichhornia crassipes (MART.) SOLMS] in ponds and in irrigation canals. To evaluate the dissipation of the herbicide applied, water bodies both with and without this plant were treated with glyphosate. Glyphosate was surface sprayed at the rate of 1.166kg a. e./ha in the model experiment and 1.020kg a. e./ha in the field experiments. The water hyacinth in ponds and irrigation canals was controlled at the rates applied and residue of the herbicide in the aquatic environment immediately after the treatment was found to be less than 1ppm. Moreover, glyphosate dissipated rapidly from the aquatic environment, with less than 22% of the maximum concentration remaining 1 day after the treatment in the ponds; no detectable residue was found in the canals 4hr after treatment. Glyphosate was thus concluded to be an effective and safe herbicide to use in the control of water hyacinth in an aquatic environment.