AQUATIC WEED
CONTROL
Ponds
 14,000
ponds east of highway 17
Ponds
Two kinds of ponds
 Ones that have weeds
 Ones that will have weeds
AQUATIC WEEDS
Algae
 Photosynthesizing plant

No roots, leaves, or flowers
AQUATIC WEEDS
Algae
 Microscopic algae: turns water green
AQUATIC WEEDS
Algae
 Filamentous: strands attach to rocks or
float in mats
AQUATIC WEEDS
Algae
 Chara: resemble flowering plant

Can be toxic to fish
AQUATIC WEEDS
Flowering Plants
 Submersed

Rooted plants that don't reach the surface
AQUATIC WEEDS
Flowering Plants
 Free-floating

Floating plant that has dangling unattached
roots
AQUATIC WEEDS
Flowering Plants
 Free-floating

Water Lettuce
AQUATIC WEEDS
Flowering Plants
 Free-floating

Water Hyacinth
AQUATIC WEEDS
Flowering Plants

Free-floating

Water Hyacinth
AQUATIC WEEDS
Flowering Plants
 Free-floating

Duckweed
AQUATIC WEEDS
Flowering Plants
 Rooted-floating

Crested Floating Heart
AQUATIC WEEDS
Flowering Plants
 Emergent

Rooted and emerging above water surface
AQUATIC WEED GROWTH
LIGHT
 Photic zone is the water with enough light
to support growth
 Bottom of photic zone is 1% of full sunlight
 Silt water = 3"
 Clear water as deep as 300'
AQUATIC WEED GROWTH
NUTRIENTS
Nitrogen and phosphorus
 Phosphorus is the limiting nutrient

P
Most important to free-floating plants
pollution can cause algal blooms
 Runoff is major contributor
AQUATIC WEED CONTROL
Nutrient control
 Buffer vegetation on shore

Unmowed strip
Shoreline
 Turf
will be undercut
AQUATIC WEED CONTROL
AQUATIC WEED CONTROL
Nutrient control
 Buffer vegetation on shore

Wetland plants
Shoreline
 Vegetate

shoreline
Wetland plants
• Wetland carpet
AQUATIC WEED CONTROL
Nutrient control
 Floating wetland


Dangling roots support microbes (biofilm)
Absorb nutrients
Shoreline
Riprap shoreline
 Stones control emergent weeds
AQUATIC WEED CONTROL
Rip rap
 Stabilize shoreline
AQUATIC WEED CONTROL
Mechanical
 Weed cutters
that remove
weeds
 Slow

2 acres/day
AQUATIC WEED CONTROL
Drawdown
 Solidify floating nutrients
 Kill submersed weeds
AQUATIC WEED CONTROL
Non-toxic blue dyes
 Blocks light below 2'
AQUATIC WEED CONTROL
Biological
 Alligatorweed Flea Beetle

Release controlled alligatorweed where flea
beetle can overwinter
 Water


Hyacinth
Mites, weevils and fungus released
Limited success
AQUATIC WEED CONTROL
Aeration
 Fountains and turbines


Aerobic conditions support
microbes and fish
Reduce algae?
AQUATIC WEED CONTROL
Grass carp
 Triploid (sterile)
 Consume massive amounts of algae and
weeds
 Live 10 years
AQUATIC WEED CONTROL
Tilapia
 Feed on algae
 Harvest to eat
AQUATIC WEED CONTROL
Barley bales
 Releases natural chemical
 Green water only
AQUATIC WEED CONTROL
UV Filter
 Water passes by UV
bulb
 Controls algae only
 Algal cells clump
together or die
AQUATIC WEED CONTROL
Chemicals
 Some that are labeled for aquatic use
 Consult label
 Liquid, granule or pellet formulation

Sinker adjuvant
AQUATIC HERBICIDES
Copper Sulfate (Cutrine)
 Controls algae in drinking water supplies
 Alkaline water (high carbonates)
precipitate out copper

Copper Chelates more stable in alkaline water
AQUATIC HEBRICIDES
Emerged or floating weeds
 Diquat (Reward)

Less effective in muddy water
 2,4-D
(Aquacide)
 Glyphosate (Rodeo)
AQUATIC HEBRICIDES
HERBICIDE APPLICATIONS
 Start control early to avoid oxygen
depletion

Repeat other half after 2 weeks
Fish Kill
 MO
decomposing plant
material utilizes oxygen
 Heavy weed or algae kill can
deplete oxygen from water and
kill fish
 Control only 1/2 of area
 High temperatures have less
oxygen

More susceptible to fish kill
AQUATIC HEBRICIDES
 Volume
needed for algae and free floating
weeds
Acre-feet = surface area (acres) X
average depth
 Average

depth
Half of maximum depth
OR

Average of several measurements
Kiawah
 115
ponds
 343 acres
 49 miles of shoreline
Kiawah
 Bivalves

(clams) filtering capacities
Attaching to grid to floating wetlands, sinking
them
 Herbicide
 Bioaugmentation
 Tilapia
 Cost
and Grass Carp
about $19/A annually
Aquatic Weed Database
 http://aquaplant.tamu.edu/