Evaluation of Two Fluridone Formulations for the Control of Hydrilla in Gatun Lake, Panama Canal Zone

摘要

Hydrilla has become a significant aquatic plant problem in the Panama Canal Zone in recent years. To combat this growing threat to the use of Gatun Lake, fluridone, 1-methyl-3-phenyl-5-(3-(trifluoromethyl)phenyl)-4(1H)-pyridinone, was applied as a 4 lb/gal aqueous suspension and 5 percent pellet at rates of 0, 0.84, 1.70, 3.36, and 6.72 kg/ha active ingredient in 18 hydrilla test plots. Significant reduction in hydrilla biomass occurred after 84 days in plots treated at rates of 1.70 kg/ha or greater, while insufficient control of hydrilla occurred in plots treated at 0.84 kg/ha. Fluridone did not adversely affect dissolved oxygen and other water quality parameters, nor were there any noticeable disturbances of the plankton and benthic communities. The residue levels in both the water column and hydrosoil had decreased to less than 15 percent of the applied compound by 56 days after application. The observed responses were attributed to the small quantity of herbicide added to the water column. (Author)