Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/6280
Title: Herbicide application technique development for flowing water : summary of research accomplishments
Authors: University of Florida. Center for Aquatic Plants.
Aquatic Plant Control Research Program (U.S.)
Getsinger, Kurt D.
Fox, Alison M.
Haller, William T.
Keywords: Aquatic plant control
Eurasian watermilfoil
Herbicide concentration/exposure time
Herbicides
Hydrilla
Rhodamine WT
Submersed plant stands
Water exchange
Publisher: Environmental Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Miscellaneous Paper
Abstract: Using herbicides to control submersed plants in static water conditions is a predictable and effective method for managing nuisance vegetation; however, chemical applications in areas of high water exchange can often result in inconsistent control of target plants. Poor plant control can be related to concentration/exposure time (CET) relationships of particular herbicides and target plant species. Many unsuccessful treatments can be attributed to off-target movement of treated water due to hydrodynamic processes. A long-term work unit was initiated to examine the problems and inconsistencies associated with using herbicides in flowing-water systems. The objectives of this effort were to (A.) characterize flow velocities and water-exchange patterns in submersed plant stands under a variety of simulated and field conditions, (B.) evaluate application techniques that maximize herbicide contact time in flowing-water environments, and (C.) provide guidance to operational personnel for improving the control of nuisance submersed vegetation in high water-exchange environments. Field studies using electronic flowmeters and tracer dyes showed that dense stands of submersed macrophytes substantially alter water movement in lotic environments, potentially reducing herbicide contact time. Intrastand flow velocities can be quite low compared with velocities along the outside edges of the plant stand. Results from more sensitive tracer dye studies indicated that subtle water-exchange patterns (both within and outside stands), driven by temperature, wind, and other factors, can also reduce herbicide contact time. Additional field studies coupled water-exchange information with laboratory-derived CET relationships and verified the predicted efficacy against Eurasian watermilfoil and hydrilla. Correlations were established between the behavior of the inert dye rhodamine WT (RWT) with selected herbicides in a variety of flowing-water systems, demonstrating that RWT can be used to simulate herbicide dissipation. These dye/herbicide evaluations contributed to the development of prescription treatment strategies to improve the control of Eurasian watermilfoil and hydrilla. Field verification of these strategies occurred in 10 lake, reservoir, and river systems around the country.
URI: http://hdl.handle.net/11681/6280
Appears in Collections:Miscellaneous Paper

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