Environmental Fate and Aquatic Impacts of Hexzinone Applied at a High Rate for Planting Site Preparation
Most environmental fate and impact concerns associated with the use of forest herbicides are related to offsite movement during and after application. The environmental fate and ecosystem impacts of forest herbicides are governed by movement and transformation in the atmosphere, above ground vegetation, soil surface, soil rooting zone, surface water, and groundwater. Herbicides and their breakdown products are transported within ecosystems mainly through the water cycle, but drift, volatilization, photodecomposition, and other forms of degradation also affect movement directly or indirectly. Precipitation and evaporation are the principal driving forces in the processes of runoff, leaching, and plant uptake and they have been discussed in great detail for forest watersheds by Hewlett (1982), Anderson et al. (1976), and Crossley and Swank (1987). Many herbicide fate studies have been conducted in the southern pinery of the United States of America (USA). Those studies have been reviewed by Michael and Neary (1993).). However, few studies exist in the literature that have examined the potential impacts of forest herbicides to stream biota.