Control of Variable Watermilfoil in Bashan Lake, CT with 2,4-D: Monitoring of Lake and Well Water.
Variable watermilfoil (Myriophyllum heterophyllum Michx.)has recently become a problem in Bashan Lake, East Haddam,CT, USA. By 1998, approximately 4 ha of the 110 ha lakewas covered with variable watermilfoil. In 1999, the milfoilwas spot treated with Aquacide®, an 18% active ingredient ofthe sodium salt of 2,4-D [(2,4-dichlorophenoxy) acetic acid],applied at a rate of 114 kg/ha. Aquacide® was used becauselabeling regarding domestic water intakes and irrigation limitationsprevented the use of Navigate® or AquaKleen®, a19% active ingredient of the butoxyethyl ester of 2,4-D. Variablewatermilfoil was partially controlled in shallow protectedcoves but little control occurred in deeper more exposedlocations. 2,4-D levels in the treatment sites were lower thandesired and offsite dilution was rapid. In 2000, the UnitedStates Environmental Protection Agency (USEPA) issued aspecial local need (SLN) registration to allow the use of Navigate® or AquaKleen® in lakes with potable and irrigationwater intakes. Navigate® was applied at a rate of 227 kg/hato the same areas as treated in 1999. An additional 2 ha ofvariable watermilfoil was treated with Navigate® in 2001, and0.4 ha was treated in mid-September. Dilution of the 2,4-D esterformulation to untreated areas was slower than with thesalt formulation. Concentrations of 2,4-D exceeded 1000 μg/L in several lake water samples in 2000 but not 2001. Nearlyall of the treated variable watermilfoil was controlled in bothyears. The mid-September treatment appeared as effective asthe spring and early summer treatments. Testing of homeownerwells in all 3 years found no detectable levels of 2,4-D.(PDF contains 8 pages.)
| Main Authors: | , , |
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| Format: | article biblioteca |
| Language: | English |
| Published: |
2003
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| Subjects: | Management, Biology, Limnology, Myriophyllum heterophyllum, 2, 4-D, Nonnative invasive weeds, Aquatic herbicide residues, Bashan Lake, Connecticut, |
| Online Access: | http://hdl.handle.net/1834/19494 |
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| Summary: | Variable watermilfoil (Myriophyllum heterophyllum Michx.)has recently become a problem in Bashan Lake, East Haddam,CT, USA. By 1998, approximately 4 ha of the 110 ha lakewas covered with variable watermilfoil. In 1999, the milfoilwas spot treated with Aquacide®, an 18% active ingredient ofthe sodium salt of 2,4-D [(2,4-dichlorophenoxy) acetic acid],applied at a rate of 114 kg/ha. Aquacide® was used becauselabeling regarding domestic water intakes and irrigation limitationsprevented the use of Navigate® or AquaKleen®, a19% active ingredient of the butoxyethyl ester of 2,4-D. Variablewatermilfoil was partially controlled in shallow protectedcoves but little control occurred in deeper more exposedlocations. 2,4-D levels in the treatment sites were lower thandesired and offsite dilution was rapid. In 2000, the UnitedStates Environmental Protection Agency (USEPA) issued aspecial local need (SLN) registration to allow the use of Navigate® or AquaKleen® in lakes with potable and irrigationwater intakes. Navigate® was applied at a rate of 227 kg/hato the same areas as treated in 1999. An additional 2 ha ofvariable watermilfoil was treated with Navigate® in 2001, and0.4 ha was treated in mid-September. Dilution of the 2,4-D esterformulation to untreated areas was slower than with thesalt formulation. Concentrations of 2,4-D exceeded 1000 μg/L in several lake water samples in 2000 but not 2001. Nearlyall of the treated variable watermilfoil was controlled in bothyears. The mid-September treatment appeared as effective asthe spring and early summer treatments. Testing of homeownerwells in all 3 years found no detectable levels of 2,4-D.(PDF contains 8 pages.) |
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