Submitted to: Saltcedar and Water Resources in the West Symposium
Publication Type: Proceedings
Publication Acceptance Date: 6/9/2003
Publication Date: 7/16/2003
Citation: Kirk, I.W. 2003. Spray drift control models. In: Proceedings of the Saltcedar and Water Resources in the West Symposium, July 16-17, 2003, San Angelo, Texas. p. 93-101. Interpretive Summary: Saltcedar was introduced into the U.S. as an ornamental tree or shrub but has become an invasive pest along stream and riverbanks. It has crowded out native vegetation and uses exorbitant amounts of water, sometimes resulting in low or no flow from once viable waterways and water supplies. Control of saltcedar is economically achieved with aerial application of herbicides. However, concerns for clean water and threatened and endangered species limit the usage of aerial application. Aerial spray models were developed that permit applicators to estimate the extent of spray drift and off-target deposits from specific aerial application conditions. Prudent use of these models and implementation of revised aerial application protocols will enable use of effective and efficient aerial applications to control saltcedar and its damaging effects on water supplies.
Technical Abstract: Saltcedar (Tamarix spp.) was introduced into the U.S. as an ornamental tree or shrub. However, it has become established on many creek and river banks, choking waterways and consuming enormous amounts of precious Western water supplies. Aerial application of chemical herbicides has been shown to be an effective and economical method for controlling saltcedar. However, off-target deposits and spray drift from aerial spray application, along with concerns for clean water and threatened and endangered species have raised concerns about aerial application as compared to other more environmentally friendly measures. Considerable progress has been achieved in recent years with technologies to limit or control off-target deposition and spray drift. Some of these technologies have been implemented in computerized models that permit aerial applicators to select and modify operational conditions to estimate and control spray drift. The USDA aerial spray nozzle atomization models and the AgDRIFT model, which are available on the Internet, provide tools for aerial applicators to understand and manage spray applications of herbicides to control saltcedar adjacent to waterways and sensitive sites.