Aquatic Plant ManagementIdentifying and Managing Aquatic VegetationEric StormerNAVFAC Atlantic

Benefits of Aquatic VegetationAquatic Plant Management

Microscopic plants (phytoplankton)

Larger algae and flowering plants (macrophytes)

Provide habitat:FishFish food organisms

WaterfowlOther wildlife

Large plants support:

Oxygenation

Shoreline stabilization

Removal of pollutants, e.g., heavy metals

Aesthetics

The Problems of Excessive Aquatic Vegetation

Aquatic Plant Management

Recreation

Too much of a good thing…

Water Hyacinth impeding water flow on a river

Spartina grass

Aquatic Plant IdentificationAquatic Plant Management

Algae

Microscopic (AKA phytoplankton)Mat-forming (AKA filamentous algae)

Chara (AKA stonewort)

Microscopic (planktonic) algae

Blooms occur in water with abundant nutrients

Mat-forming (filamentous) algae

Form floating, mat like growths. Most common problem in ponds.

Chara (AKA Stonewort)

Flowering PlantsAquatic Plant Management

Flowering Plants

Curly-leaf pondweed

Submersed Plants – alternate leaf arrangement (one leaf per node)

Exotic invasive Grows best in spring, tends

to die out in summer

Sago Pondweed

Submersed Plants – alternateleaf arrangement (one leaf per node)

Very long, almost thread-like leaves 2” – 6” in length

Individual leaves tend to be somewhat curved

May be a weed in some situations

Seeds and underground tubers are valuable food for waterfowl

Leafy Pondweed

Submersed Plants – alternate leaf arrangement (one leaf per node)

Extremely common in ponds during summer

Bear very narrow leaves 1” – 2” in length

Southern Naiad

Submersed Plants - Opposite Leaf Arrangement (two leaves per node)

Leaves are not visibly spined

Bear two leaves per node, but sometimes appear to bear three

Leaves are typically flat, straight

Brittle Naiads

Submersed Plants - Opposite Leaf Arrangement (two leaves per node)

Leaves are stiff, slightly spined

Leaves are sometimes clustered at the tips of stems

Coontail

Submersed Plants – Whorled Leaf Arrangement (3 or more leaves per node)

Leaves are branches and spined

Plant is very lightly rooted, or floating in the water column

Very common in shallow, marsh-like areas and in older ponds

Eurasian watermilfoil

Submersed Plants – Whorled Leaf Arrangement (3 or more leaves per node)

Serious pest Spreads rapidly This species typically bears

more than 10 leaflet pairs per leaf, whereas native milfoils have fewer than 10

Each node bears 4 leaves Red to olive green stems

Submersed Plants Whorled Leaf Arrangement (3 or more leaves per node)

Watermeal Duckweed

Free-floating Plants

Looks like tiny green seed or green cornmeal

Has no roots Are found in nutrient-rich

waters

1/8” – 1/4” diameter leaves Bears a small root that

hangs in the water Are found in nutrient-rich

waters

Azolla

Water hyacinth

Rooted-floating PlantsBear underground stems (rhizomes) from which growth

occursLeaves and flowers float on the water surfaceGenerally found growing in water less than 4’ – 5’ deep Include waterlily, watershield, American pondweed, and

SpatterdockWatershield and American pondweed can be weedy in

the shallow areas of ponds and lakesSpatterdock and waterlilies provide valuable wildlife

habitat and should be protected in natural lake and wetland areas

Spatterdock, AKA cow lily

American pondweed

Watershield

Waterlily

Emergent PlantsAKA shoreline plants, marginal plants – in reference to where they occur

Includes grass-like (graminoids) and broadleaved plants

Grass-like plants include: cattails, bulrushes, spikerushes, and reed canarygrass

Broadleaved plants include: willow trees, creeping water primrose, and purple loosestrife

Many of these plants spread rapidly by underground stems (rhizomes), and by seed

Cattail

Phragmites

Spikerush

Bulrush

Creeping water primrose

Purple Loosestrife

Aquatic Plant Management Methods

Aquatic Plant Management

Consider the water’sDepthVolumeTurbiditypHFlowPrevailing winds direction

Preventive Control

Mechanical Control

Hydrilla verticillata removal

Biological Control

Habitat Alteration

Nutrient Management

Habitat Alteration

Nutrient ManagementHabitat Alteration

Light inhibitors, aerationHabitat Alteration

Benthic barrier

Drawing down the lakeHabitat Alteration

HerbicidesAquatic Plant Management

Chemical Control – EPA Registered products:Used in extremely low does in the water.

They do not persist very long (usually only a few days).

They do not bioaccumulate in the fatty tissues of humans or animals .

Before Using HerbicidesProperly identify the weed.Never apply chemicals in or around water unless they are specifically labeled for aquatic use.

Always follow any water use restrictions (for drinking water, livestock, irrigation, etc.).

Apply the correct dose.

Before Using HerbicidesMake timely applications. Late spring – when plants are young and growing actively – is usually the best time to apply herbicides. Later applications may result in fish kills, as water will be warmer, vegetation is usually dense/extensive, and oxygen levels are low.

Apply when the temperature is correct; herbicides do not affect aquatic plants when the water is too cold.

Before Using HerbicidesRemember – some herbicides are contact based; can be applied as spot treatments for quick kill. Others are translocated; will work but take longer.

Retreat as required. Most aquatic herbicides have no effect on seeds and underground structures that lie dormant over winter.

Consider the following - Herbicides:Expense Available time frame for controlApplication typeFormulationLabel informationVegetation decayLicenses

Aquatic Weed Herbicide Typical Dose1 Restrictions2

Algae (microscopic, mat-forming, Chara)

copper sulfate (25% Cu) 2 7 lbs/A-ft Do not use in trout- or koi-bearing waters

copper chelates Dose varies by formulation Do not use in trout- or koi-bearing waters

sodium carbonate peroxyhydrate (GreenClean®, Phycomycin®) 3-100 lbs/A-ft None, but check specific labels

endothall (Hydrothol 191®)

liquid form 0 6-18 pt/A-ft I, L, D = 7-25 days

granular form 3-81 lbs/A-ft

Subm ersed plants (pondweeds, naiads, elodea)

endothall (Aquathol K®)

liquid form 0 6-3 2 gal/A-ft I3, L, D = 7-25 days

granular form 2 2-22 lbs/A-ft I, D = 7 days

diquat (Reward®) 0 5-2 gal/SA I = 1-5 days; D = 1-3 days; L = 1 day

fluridone (Sonar®, Avast! ®)

Dose varies by formulation I = 7-30 days Do not apply within a quarter mile of potable water intakes4

Subm ersed plants (Eurasian watermilfoil, coontail)

2,4-D

Navigate® 100-200 lbs/SA I, D Note precautions on label DMA 4 IVM® Up to 2 8 gal/A-ft

triclopyr (Renovate®)

0 7-2 3 gal/A-ft

D Note setbacks when applying near potable water intakes

fluridone (Sonar®, Avast! ®)

Dose varies by formulation

I = 7-30 days Do not apply within a quarter mile of potable water intakes4

Free-floating plants

(duckweed, watermeal)

diquat (Reward®) 1-2 gal/SA (add surfactant) I = 1-5 days; D = 1-3 days; L = 1 day

fluridone (Sonar AS®, Avast! ®)

0 12-0 24 qt/A-ft I = 7-30 days Do not apply within a quarter mile of potable water intakes4

Rooted-floating plants (waterlilies, spatterdock)

Glyphosate (AquaMaster® and others plus surfactant, Glyphomate 41® without added surfactant)

Dose varies according to species Consult label

Do not apply within a quarter mile upstream of potable water intakes

Em ergent plants (cattails, willows, grasses and

other perennial plants)

Glyphosate (AquaMaster® and others plus surfactant, Glyphomate 41® without added surfactant)

Dose varies according to species Consult label

Do not apply within a quarter mile upstream of potable water intakes

Questions?