Title: Aquatic Plant Management
1Aquatic Plant Management
- Louis Helfrich, Ph.D.
- Department of Fisheries Wildlife Sciences
- Virginia Tech
2Plants 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.
3Plants 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
4Too 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
5Why weeds? Nutrients, Light
6Why weeds?
- Shallow water
- Clear water
- Excess fertility (nutrients)
- Invasion of exotic weeds
American Lotus, Nelumbo lutrea
7FertilizationCan you fertilize weeds away? No
8Aquatic Weed Prevention
- Prevent fertilizer runoff
- Prevent soil erosion
- Do not feed grass clippings
- Do not feed fish and ducks
- Fence livestock
- Steep banks
9- Aquatic plants can be divided into
- (1) algae
- (2) rooted water plants.
10Algae or Turbidity?
11- Rooted aquatic plants are distinguished from the
algae by the presence of true leaves, stems,
roots, and flowers.
12Common Floating Plants
Watershield
Spatterdock, Nuphar advena
13Submerged PlantsExotics
14Emerged and Shoreline Plants
Arrowhead
Cattail
15Plant Dominance
- Algae
- Turbid water
- Fertile, P
- Planktivourous, carp
- Small zooplankton
- Ducks geese
- Macrophytes
- Clear water
- Fertile, less P
- Predators
- Large zooplankton
- No waterfowl
16Weed Control Methods
- Watershed management
- Physical
- Biological
- Chemical
17Weed Control Physical Removal
- Drain
- Dredge
- Dragging
- Raking
- Cutting
- Skimming
- Harvesting
- Aeration
18Herbivorous animals
- Fish, geese, and swans
- Nutrient pumps
- Permits for exotic animals
19Herbicides?
- Expensive
- Short-term
- Toxic
- Registered
- Liability
- Dosage
- Timing
- Fish Kills
- Water-use restrictions
20Chemical 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)
21Application Timing
- Early spring
- Actively growing
- Cool water
- Slow decay
Pickerel weed, Pontederia
22Application Variables
- Area treated
- Water depth
- Water temperature
- pH
- Hardness
- Flow Exchange rates
- Weed density
- Weather conditions
- Suspended particles
Arrow Arum, Peltandra virginica
23Chemical Control
- 1/3 of pond at a time
- Follow label
- Observe waiting periods
24Aquatic Problems
- Water weeds
- Water quality
- Muddy water
- Leaking ponds
- Nuisance animals
- Poor fishing
- Fish kills
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26http//aquat1.ifas.ufl.edu/welcome.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
http//www.ext.vt.edu/pubs/fisheries/420-251/420-2
51.html
27The 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.
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29Table 2. Waiting period (days) before using water
after application of aquatic herbicides
(Helfrich et al. 1996).
Giant Salvia, Salvinia molesta, exotic
30Watershed ManagementWhy weeds? excess fertility
- Livestock waste
- Fertilizer runoff
- Waterfowl
31Water Plant Controlhttp//www.ext.vt.edu/pubs/fis
heries/420-251/420-251.html
- Watershed management
- Physical
- Biological
- Chemical
- Water dyes
- Barley straw
32- 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.
33High Diversity of Aquatic Plant Species
Pondweeds, Potamogeton spp.
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35Algae or Vascular Plant?
Chara Algae
36Why water weeds?Excess fertility!
- Livestock waste
- Crop fertilizer
- Ducks geese
- Shallow water
- Clear water
- Bank slope
- Exotic weeds
37Physical controls
- Water diversion
- Dilution
- Dredging
- Deepening
- Water level manipulation
- Bottom sediment covering
- Light elimination
- Harvesting
38Barley 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.
39Herbicide Selection
- Copper compounds
- algae
- Flouridone (sonar)
- Submersed floating
- Glyphosate (rodeo)
- emergent
- 2-4D
- submersed
- Diquat
- algae submersed