ABSTRACT: Surface Enhanced Raman is a promising analytical method for harmful pesticides detection. Herein, we demonstrate a rapid method to directly monitor 2,4-D pesticide in water without the need of sample pre-treatment by using Silver-Gum Arabic (Ag-GA) electrochemically co-deposited SERS substrates. The facile electrochemical synthesis of the large-area (40 µm x 20 µm) SERS substrates needs only 10 seconds, with 2 μL AgNO3 and Gum Arabic mixed solution. Different morphologies including Ag-GA spherical nanoparticles and nano dendrites were synthesized by tuning the deposition parameters. This study therefore offers a novel way to fabricate SERS substrates for rapid determination of 2,4-D pesticides down to 1 pM in deionized water and 0.15 nM in commercial bottled and also river water samples.