Transcript Document

Integrated Pest Management
& Certification Training
Aquatic Weed Management
Richard D. Lee, Ph.D.
IPM Specialist
Bureau of Land Management
Aquatic Plants
 In natural systems such as lakes and
ponds, light to moderate growths of
aquatic plants serve useful purposes:
 Provide
oxygen, food and cover for fish
and other aquatic organisms, and may
stabilize bottom sediment.
Aquatic Plants
 In overabundance, many species become
“weedy” as they crowd out desirable plants,
adversely affecting other aquatic life and our
ability to use the water:




Recreation
Creation of foul odors and discoloration
Fish kills
Blockage of water flow
Aquatic Weeds
 My goal this morning is to provide you
with the necessary background
information to allow you to understand
the procedure for developing an aquatic
weed management plan.
Classification of Aquatic
Weeds
 Two groups of aquatic plants:
 1. Algae - simple plants without roots, leaves
or stems.
 They reproduce by cell division,
fragmentation, or by spore formation.

2. Vascular plants - plants having roots, stems,
leaves, and flowers.
 There are four classes - submersed, freefloating, rooted floating, emerged plants.
Aquatic Weeds - Algae
 Three types:
 1. Microscopic algae - single celled or colonial
algae. Also referred to as “Phytoplankton”
when suspended in water. During the
daylight - give off oxygen, During night remove oxygen.
If overabundant - fish kill due to oxygen
removal from water - referred to as an
“algal bloom” - the result of too much
fertilizer in pond.
Aquatic Weeds - Algae
 Three types:
 1. Microscopic algae
 2. Filamentous algae - thread-like filaments
that form mats on surface of the pond. As
algae photosynthesize, oxygen gets trapped in
the body causing them to rise to the surface as
clumps.
Examples:
- Spirogyra - bright green and slimy
- Cladophora - cotton mat algae, due
to texture
- Pitophora - horsehair coarse
Aquatic Weeds - Algae
 Three types:
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1. Microscopic
2. Filamentous
3. Chara - looks more like a plant with leaves
needle-like and arranged in whorls
along the “stem”.
Musky odor and gritty surface due to
calcium deposits. Also called
“stonewort”
Submersed
Plants
Aquatic Weeds - Vascular
Plants – Submersed Plants
 Four Groups:
1. Submersed plants - rooted to the bottom
and completely submersed except for
flowers which may extend above the
water. Often referred to as “moss”.
Identification based upon:
* Leaf arrangement
* Leaf shape
Aquatic Weeds - Vascular
Plants
 Submersed Plants - Alternate Leaves:
 One
leaf per node
 PONDWEEDS - (Potamogeton sp.)
Curly Leaf Pondweed
 Sago Pondweed
 Leafy Pondweed

Aquatic Weeds - Vascular
Plants
 Submersed Plants - Opposite Leaves:
 Two
leaves per node
 NAIADS (Najas sp.)
Southern naiad
 Brittle naiad

Aquatic Weeds - Vascular
Plants
 Submersed Plants - Whorled Leaves:
 Three or more leaves per node, arranged in a whorl.
 Most serious submersed aquatic plants fit in this
group.
 Examples:
 COONTAIL - Ceratophyllum demersum
 AMERICAN ELODEA - Elodea canadensis
 EURASIAN WATERMILFOIL - Myriophyllum
spicatum There are other watermilfoils,
including parrotfeather.
 HYDRILLA - Hydrilla verticillata
Got to Know Your Weeds:
Eurasian Watermilfoil
 Eurasian Watermilfoil
 Myriophyllum spicatum
 Submerged, rooted
perennial.
 Grows in depths of up to
15 feet deep.
 Forms dense mats.
Got to Know Your Weeds:
Parrotfeather
 Parrotfeather
 Myriophyllum aquaticum
 Submerged, rooted
perennial.
 Forms dense mats.
 Whorled leaves.
Got to Know Your Weeds:
Hydrilla
 Hydrilla
 Hydrilla verticillata
 Forms dense mats.
Aquatic Weeds - Vascular
Plants – Free Floating

Four Groups:
1. Submersed plants
2. Free-floating Plants - these plants live
unattached to the soil. There are
roots, extend only in the water for
nutrient uptake.
Majority of the plant is flattened or
boat- shaped clusters of leaves with
short segmented stems.
Free Floating
Aquatic Weeds - Vascular
Plants
 Free-floating Plants:
 Examples:
 DUCKWEED - (Lemna sp.) - 0.5” across,
with 2 to 4 leaves.
 WATERMEAL - (Spirodela sp.) - 1/16”
diameter
 GIANT SALVINIA – (Salvinia molesta)
 WATER HYACINTH - (Eichhornia crassipes)
- major aquatic weed of concern
Got to Know Your Weeds:
Giant Salvinia
 Giant Salvinia
 Salvinia molesta
 Native to South America
 First found in U.S. in 1995 in
South Carolina.
 Now found in 24 watersheds
in Texas, California, Arizona,
Louisiana, Mississippi,
Alabama, Georgia, &
Florida.
 Southern States most
susceptible.
Got to Know Your Weeds:
Giant Salvinia
 Giant Salvinia
 Salvinia molesta
 Forms dense mats.
Got to Know Your Weeds:
Water Hyacinth
 Water Hyacinth
 Eichhornia
crassipes
Aquatic Weeds - Vascular
Plants – Rooted Floating
 Four Groups:
1. Submersed plants
2. Free-floating Plants
3. Rooted Floating Plants - also referred to as
“Emersed Weeds” on some labels.
Plants are rooted in the bottom sediments
in shallow water. Leaves are floating or
erect.
Plants identification by leaf shape and
petiole attachment.
Rooted Floating
Aquatic Weeds - Vascular
Plants
 Rooted Floating Plants:
 Center Attachment
of Petiole
WATER LOTUS
 WATERSHIELD
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 Cleft
or Edge Petiole Attachment
WATER LILY
 SPATTERDOCK

Aquatic Weeds - Vascular
Plants – Emergent Plants
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Four Groups:
1.
2.
3.
4.
Submersed Plants
Free-floating Plants
Rooted Floating Plants
Emergent Plants - Most of the plant is
above the water surface.
Common Examples:
Purple Loosestrife
Salt Cedar
Emergent Plants
Got to Know Your Weeds:
Purple Loosestrife
Aquatic Weeds - Management
 Remembering our four step approach to
weed management will assist in
developing a management plan for
aquatic weeds:
 1.
Prevention
 2. Early Detection
 3. Timely Management
 4. Site Rehabilitation
Aquatic Weeds - Management
 Prevention:
 We
need to be aware of the potential threat
aquatic weeds have for our areas and
learn to recognize those weeds of concern.
Giant Salvinia - is a problem in Texas and has
the potential to make it into this area.
 Purple Loosestrife - a serious problem in the
Eastern portion of the U.S. and moving our
way.

Aquatic Weeds - Management
 The key here - is
we need to be
looking at what is
growing in our
ditches and lakes.
Aquatic Weeds - Management
 Early Detection:
 Timely Management:
 Biological
 Mechanical
 Cultural:
Proper construction – steep slopes – keep
water moving
 Draining/Drying – species dependent
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 Use
of Herbicides
Aquatic Weeds - Management
 Timely Management:
 Biological
- the use of living organisms to
manage other living organisms.
Limited options available.
Tilapia – plant eating fish
 White Amur – plant eating fish, concerns
regarding its environmental impact.

Mechanical 
Cutting, Mowing, Raking, Digging
Aquatic Weeds - Management
 Herbicides Available:
– Copper sulfate
 Submersed – Diquat, Endothall, Fluridone,
2,4-D
 Free Floating – Diquat,
 Emersed – Glyphosate, Triclopyr
 Algae
Aquatic Weeds - Management
 Use of Herbicides - before using a herbicide,
make sure you have answers for the
following questions:

1. What is the use of the treated water?
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2. Characteristics of the Environment
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3. Characteristics of the Water
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4. Characteristics of the Selected Herbicide
Aquatic Weeds - Management
 Herbicides and Static Water:
 Floating and emerged weeds are easy to manage.
 Submerged weeds and algae not real difficult.
 Herbicides and Flowing Water:
 Floating and emerged weeds are still easy to
manage.
 Submerged weeds and algae can only be
managed effectively through continuous
application at a particular point to maintain a
specified level of herbicide concentration - it’s not
easy.
Aquatic Weeds - Management
 Application of Aquatic Herbicides:
 1. Application equipment - is it in good working
order.
 2. Determine area to be treated:
Aquatic Situation
Determining Treated Area
----------------------------------------------------------------------- Algae
Water Volume - acre -ft
 Submersed Plants
Water Volume - acre-ft
 Free-Floating
Surface Area - acres
 Rooted Floating Plants
Surface Area - acres
 Emergent Plants
Surface Area - acres
Aquatic Weeds - Management
 Application of Aquatic Herbicides -
Pond:
 Surface Area:
Free-floating, rooted-floating, and emerged
weeds
 Two dimensional - length X width
 Rate of herbicide application based upon
“amount/acre”

Aquatic Weeds - Management
 Application of Aquatic Herbicides - Pond:
 Water Volume:
 Algae and submerged
 Three dimensional - length X width X depth
 Rate of herbicide application based upon
“amount/acre-ft” or “ppm” (Parts per million).
To convert “ppm” to “lbs. product required”

2.7 X PPM wanted X acre-ft = lbs. Prod.
Req.
Aquatic Weeds - Management
 Application of Aquatic Herbicides - Canal/Moving:
 Herbicide application depends upon:
 Water Volume: Average width X Average depth
= sq. ft.

Flow Speed: Distance water moves per unit of time
= ft/sec

FLOW RATE: Water volume X Flow Speed
= cubic feet/sec
Aquatic Weeds - Summary
 1. Different Types of Weeds:
 Algae
 Submersed Weeds
 Free-floating Weeds
 Rooted Floating Weeds
 Emergent Weeds
 2. Management Plan Development