Factors affecting the efficacy of acrolein in irrigation channels in southern Argentina

Abstract

Growth of the submerged weed Potamogeton pectinatus L. is a major problem in the irrigation channels located in the Lower Valley of the Colorado River (39 10¢–39 55¢S; 62 05¢–63 55¢W) in Argentina. Previous studies indicate that weed control with acrolein is effective in reducing submerged plant biomass. In this study, we evaluated the influence of some variables affecting acrolein and its dissipation in water. Three main parameters, acrolein dosage, the height of the plants and the velocity of water contributed to 80% of the reduction of the submerged weed biomass. Water flow and concentration of the chemical explained 68% of the factors influencing the dissipation of the herbicide. Water velocity, electrical conductivity, pH and the duration of application have a secondary effect in the dissipation process. The constant rate of dissipation (K) was 0.235 L h)1 (SD ±0.125), implying that the chemical will disappear from the system in <24 h. As a practical guideline for the control of mature, dense stands of P. pectinatus within the irrigation system under study, the following conditions are advisable: flow volumes of 500 L s)1 or higher, water velocity of 0.42 m s)1 or more and c. 6.5 mg L)1 concentration of acrolein for at least a 11-h period.