Response of Aquatic Plants to Combinations of Endothall and Copper

Abstract
The addition of 0.5 and 5.0 ppmw of 7-oxabicyclo [2.2.1] = heptane-2,3-dicarboxylic acid (endothall) to solutions of copper sulfate pentahydrate (CSP) at 1.0 ppmw of copper applied to the roots of emersed parrotfeather (Myriophyllum brasiliense(Camb.) increased the copper content of the roots of these plants. Growth of parrotfeather was inhibited by root applications of 0.5 and 5.0 ppmw of endothall, but CSP did not increase its phytotoxicity. However, a synergistic effect, as determined by dry weight, was calculated after treatment of hydrilla (Hydrilla verticillataCasp.) with a combination of 5.0 ppmw of endothall plus CSP at 1.0 ppmw of copper. An increase in copper uptake and a reduction in phosphorus levels was associated with those plants treated with the combination.