APPLICATION METHODS OF PESTICIDES TO AN AQUATIC MESOCOSM IN ORDER TO SIMULATE EFFECTS OF SPRAY DRIFT

A treatment procedure was developed to mimic spray drift deposition of pesticides on the water surface of outdoor experimental ditches. The performance of this procedure was evaluated in two studies (using the pesticides chlorpyrifos and linuron, respectively) by testing the capability to apply pesticides to the ditches accurately, without contaminating adjacent control ditches. This was done by measuring the volume and concentration of the spray, by chemical analysis of the compounds in the ditch water and by measuring spray deposition on the water surface. After the first study some slight modifications were made to the treatment procedure. In the second study, in which eight ditches were treated with a fixed volume of spray of varying pesticide concentrations, it could be shown that the actual volumes dosed closely matched the intended volume (mean value per treatment within 1% of intended value; coefficient of variation