Correlation of fluridone and dye concentrations in water following concurrent application

Abstract

AbstractHerbicide residue samples are expensive and time‐consuming to collect and analyze. To test whether Rhodamine WT dye could simulate the dissipation of fluridone, concurrent applications of the chemicals were made in the weed‐infested Three Sisters tidal canals (Citrus Co. Fl) and a shallow lake in the Upper St Johns River, Florida. Dye concentrations were measured using a field fluorometer and fluridone concentrations were analyzed by an HPLC method. The coefficient of correlation between dye and herbicide was 0.99 in the canals and 0.93 in Lake Hell ‘n’ Blazes (Upper St Johns River) over 340 and 93 h respectively. Half‐lives of the chemicals were not significantly different for either site. The importance of these data in relation to herbicide registration is discussed.