aquatic plant management
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Aquatic Plant Management. Louis Helfrich, Ph.D. Department of Fisheries & Wildlife Sciences Virginia Tech. - PowerPoint PPT PresentationTRANSCRIPT
Aquatic Plant ManagementLouis Helfrich, Ph.D.
Department of Fisheries & Wildlife SciencesVirginia Tech
Plants: Problem or Benefit?Photosynthesis by aquatic plants, both algae and rooted water plants, represents the major source - contributing from 70 to 90% of the dissolved oxygen. Aquatic plants can trap excessive nutrients and detoxify chemicals. Aquatic wildflowers such as the water lily are sold and planted to provide floral beauty in water gardens.
Plants serve as nursery habitat and the foundation of the aquatic food chain. They provide food, dissolved oxygen, and spawning
and nesting habitat for fish and waterfowl.
• Wildlife
• Food
• Nursery
• Shelter
• Critical habitat
Too many plants! A weed is simply a very
successful competitor for space, light, and nutrients.
• Restricted recreation
• Fish kills • Fish flavor
problems • Pond water odor
problems • Drinking water
taste problem • Stunted fish
growth
Why weeds?
• Shallow water • Clear water • Excess fertility
(nutrients) • Invasion of exotic
weeds
American Lotus, Nelumbo lutrea
Aquatic Weed Prevention
• Prevent fertilizer runoff
• Prevent soil erosion • Do not feed grass
clippings• Do not feed fish and
ducks • Fence livestock • Steep banks
Rooted aquatic plants are distinguished from the algae by the presence of true leaves, stems, roots, and flowers.
Plant Dominance
1. Algae2. Turbid water3. Fertile, P4. Planktivourous, carp5. Small zooplankton6. Ducks & geese
1. Macrophytes2. Clear water3. Fertile, less P4. Predators5. Large zooplankton6. No waterfowl
Weed Control: Physical Removal
• Drain • Dredge• Dragging• Raking• Cutting• Skimming• Harvesting• Aeration
Herbicides?
– Expensive– Short-term– Toxic– Registered– Liability – Dosage– Timing– Fish Kills– Water-use
restrictions
Chemical Control • Algae
– Copper Sulfate,
– Copper Complex (Cutrine)
• Submerged Weeds
– Diquat (Reward),
– Fluridone (Sonar / Avast),
– 2, 4-D, (Aqua-Kleen)
– Endothal (Aquathol K)
• Floating (Duckweed and Watermeal)
– Diquat,
– Fluridone
• Emergent and floating Plants
– Endothal, Fluridone, 2,4-D
– Glyphosate (Rodeo)
Application Timing
• Early spring • Actively growing • Cool water • Slow decay
Pickerel weed, Pontederia
Application Variables
• Area treated• Water depth• Water temperature• pH• Hardness• Flow Exchange
rates• Weed density• Weather conditions• Suspended particles
Arrow Arum, Peltandra virginica
Aquatic Problems
1. Water weeds
2. Water quality
3. Muddy water
4. Leaking ponds
5. Nuisance animals
6. Poor fishing
7. Fish kills
http://aquat1.ifas.ufl.edu/welcome.html
http://www.ext.vt.edu/pubs/fisheries/420-251/420-251.html
Control Methods For Aquatic Plants in Ponds and Lakes
Authors: L. A. Helfrich, R.J. Neves, G. Libey, and T. Newcomb, Extension Specialists, Fisheries and Wildlife Sciences, Virginia Tech
Publication Number 420-251, posted March 2000
The density of aquatic plants (both algae and rooted macrophytes) is largely a function of (1) nutrient concentrations (phosphorous and nitrogen) and, (2) light. In
general, nutrient-rich, shallow lakes experience greater nuisance water weed problems than nutrient-poor, deep lakes.
Herbicide Irrigation Fishing Livestock Swimming Drinking
Fluridone (Sonar) 30 0 0 0 0
Glyphosate (Rodeo) 0 0 0 0 2
Chelated Copper 0 0 0 0 0
Diquat (Reward) 5 0 1 1 3
Endothal
Aquathal K 14 3 14 1 <25
Aquathal G 7 3 14 0 <25
Table 2. Waiting period (days) before using water after application of aquatic herbicides (Helfrich et al. 1996).
Giant Salvia, Salvinia molesta, exotic
Water Plant Controlhttp://www.ext.vt.edu/pubs/fisheries/420-251/420-251.html
• Watershed management
• Physical• Biological• Chemical
– Water dyes
– Barley straw
Aquatic plants can be divided into (1) algae and, (2) rooted water plants. Algae are primitive, simple plants which lack true roots, leaves, or flowers and reproduce by spores, cell division, and fragmentation. They range in form from unicellular (single cells), through colonial and filamentous types, to advanced forms which resemble the higher aquatic plants. Some are microscopic, but impart green color to the water, others are visible as surface films or bottom dwelling forms which are often confused with higher aquatic plants.
Why water weeds?Excess fertility!
• Livestock waste• Crop fertilizer• Ducks & geese
• Shallow water• Clear water• Bank slope• Exotic weeds
Physical controls
(1) Water diversion(2) Dilution(3) Dredging(4) Deepening(5) Water level
manipulation(6) Bottom sediment
covering(7) Light elimination(8) Harvesting
Barley Straw?
• The rate is 2-50 grams/square meter
• 1 acre pond = 4046 m2 of water• Therefore, treatment of 1 acre
pond at the lowest recommended dose, 2 grams would require 8092 grams or 17.8 pounds of straw.
• Source: Aquatic Ecosystems 1-877-347-4788. They charge $55.00 for 11 pounds of barley straw.
• Minimum treatment for 1-acre pond costs $110/acre.