AN OVERVIEW OF CHEMICALS FOR AQUATIC PLANT CONTROL

Abstract

ABSTRACT Scientists' role is to separate fact from fiction to assure that decisions be based upon valid evidence rather than emotions and misinformation. The use of chemicals for aquatic vegetation control is one issue commonly surrounded with fear and uncertainty by the general public, environmental groups, and politicians. This has led to restrictive laws in some States which severely limit or prohibit the application of registered aquatic pesticides. In-lake rehabilitation methods and watershed protection measures have achieved mixed results in controlling lake nutrient concentrations to suitably limit macrophyte or algae growth. For many bodies of water, high quality water is not presently economically or technologically feasible. However, symptomatic treatment of nuisance aquatic plant growth with chemicals or through integrated pest management methods can provide waterways acceptable for recreational and functional use. Historically, the chemicals used for aquatic macrophyte and algae control were sodium arsenite and copper sulfate, respectively. These did pose a threat to the environment from overdose and abuse in attempts to eradicate rather than manage aquatic plant problems. Today's chemicals and application techniques are more selective and sophisticated. Toxicity limits, breakdown times, and tolerances are established prior to EPA registration. Organic herbicides that characteristically degrade in the environment or become biologically inactive have replaced persistent chemicals such as sodium arsenite. Formulated, chelated copper compounds are replacing copper sulfate treatments as a safer, more effective approach. Improved application equipment, techniques using spray adjuvants, and granular formulations have helped overcome problems with drift and uneven distribution. The judicious use of chemicals for aquatic vegetation control is imperative. Loss of any of our limited number of tools for maintaining suitable recreational and functional waterways through regulations imposed by the uninformed could severely limit our ability to achieve future water quality objectives.