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Netherland, M.D. and K.D. Getsinger, 1995. Laboratory
Evaluation of Threshold Fluridone Concentrations Under Static Conditions for
Controlling Hydrilla and Eurasian Watermilfoil, US Army Corps of Engineers.
Reprinted with permission from Journal of Aquatic Plant
Management (1995) 33: 33-36
Laboratory Evaluation of Threshold Fluridone Concentrations
Under Static Conditions for Controlling Hydrilla and Eurasian Watermilfoil
Abstract
Fluridone {1l-methyl-3-phenyl-[3-(trifluoromethyl)
phenyl]-4(1H)-pyridinone} was evaluated against Eurasian watermilfoil (Myriophyllum
spicatum L.) and hydrilla (Hydrilla verticillata (L.f.) Royle) under
laboratory conditions at initial treatment rates of 0.0, 0.25, 0.5, 0.75, 1.0,
2.0, 3.0, 4.0, and 25.0 µg/L for 90 days of exposure. Treatment concentrations
< 1 µg/L had no effect on either hydrilla or Eurasian watermilfoil biomass
and resulted in only a small reduction (13 to 33%) in hydrilla net
photosynthesis (PTS) and chlorophyll at 0.75 µg/L. Both hydrilla and Eurasian
watermilfoil growth were inhibited by fluridone concentrations between 1.0 to
3.0 µg/L. Rates of 1.0 and 2.0 µg/L did not reduce hydrilla biomass below
pretreatment levels, but did inhibit growth. Biomass remained static from 30
through 90 days after treatment, while chlorophyll and PTS continued to
decrease. Eurasian watermilfoil biomass and physiological variables were
inhibited as fluridone rates reached 3.0 µg/L. With fluridone concentrations
of 4.0, and 25.0 µg/L, hydrilla and Eurasian watermilfoil biomass and
physiological variables were reduced (42 to 88%) below pretreatment levels by 30
days after treatment. If PTS readings at shoot apices remained positive
following fluridone treatment, shoot biomass increased; whereas negative PTS
readings were associated with biomass decreases below pretreatment levels. In
general, the appearance of treatment symptoms was delayed as treatment
concentrations decreased.
Entire Paper
Contact: Kurt Getsinger, US Army Corps of Engineers, Waterways Experiment
Station, 3909 Halls Ferry Road, Vicksburg, MS 39180
Key Words: Hydrilla, Eurasian_watermilfoil,
Chemical_control
Product Type: Research, Control
User Type: Resource Management
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