These pages are reprinted
from www.gotalgae.com, courtesy of www.kascomarine.com.
is a wide array of aquatic plants. There are many species and varieties
that are beautiful, add to your ponds function and aesthetics, and
serve a purpose to your pond or lake. We like to call these desirable
aquatic plants. Then there are the many that quickly take over your
pond, can potentially hurt your ponds ecosystem, are an eye sore,
and don't serve much purpose to your pond or lake. These are known
as undesirable aquatic plants and are what we are referring to when
we discuss aquatic plant problems.
times, it is not difficult to distinguish between desired and undesired
aquatic plants. However, as with many things, the difference can
be determined by balance and personal taste. Aquatic plants are
essential to a healthy pond ecosystem. They can serve as a food
source for organisms in your pond, hiding places for fish and insects,
nutrient sinks (using up available nutrients), and also provide
oxygen. Aquatic plants can also enhance the aesthetics of your pond
and create a beautiful, peaceful area.
invasive, native plants are much more desirable than non native,
invasive varieties. Non native plant species out compete native
species for nutrients because the native species are in better balance
with the entire system. The non native species that overtake a pond
are rapid growers and do not have the organisms to keep them in
check because they are not native to the area. Native plants can
also grow rapidly if not monitored and held in check. Therefore,
the key is balance and preventing one specific aquatic plant from
overtaking your entire pond. A nice mix of species will provide
a healthy pond ecosystem and also a beautiful setting.
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plants, whether desirable or undesirable, can quickly take over
a pond or lake that has too many nutrients available. Nutrients
are the main cause for excessive aquatic plant growth. Only a small
amount of nutrients added to a pond can cause a lot of problems
with aquatic plant growth.
can be added to your pond in a number of ways, such as, leaves,
grass clippings, wildlife waste, and runoff from lawns, cattle pastures,
and farm fields all add a large amount of nutrients to your water.
Once they reach the pond, they are available for plant growth.
is important to look at the source of your ponds nutrients and try
to get a handle on that while you are working on the immediate problem
with aquatic plants. The treatments that are discussed on this page
can be costly as well as labor intensive and strenuous. If you do
not take any steps toward correcting the nutrient problem in your
pond, these treatments will have to be an ongoing task. You will
just be treating the symptoms of the problem, which are the weeds,
and not doing anything for the problem, which is excessive nutrients.
the Nutrient Solutions page,
you will see some detailed information on ways to prevent nutrients
from entering your pond and getting rid of the nutrients already
there. It is very important to limit the amount of nutrients that
are entering your pond; otherwise, the aquatic weed problem will
be there every year.
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the name implies, these are plants that are free floating at the
surface or have leaves that float. They typically have some sort
of root system that hangs below the plant and filters the water
for nutrients. Two common undesirable or nuisance floating aquatic
plants (not including algae which is discussed individually in the
Algae Solutions page) are Duckweed
and Watermeal. These two species of aquatic plants can cover a pond
and create a very unappealing pond or lake. They also block out
sunlight from reaching the rest of the water column which limits
growth of other aquatic plants and can limit the amount of oxygen
available for your fish. Some more desirable floating aquatic plants,
in moderation, are Water Lily (Lily Pads), Watersheild, and Spatterdock.
These plants are considered more desirable because they enhance
the aesthetics of a pond and create nice flowers. However, they
can overrun a pond and become undesirable if not controlled.
(Lemna minor) is a small, green, round or oval aquatic
plant that floats at the surface with a root that hangs below. Duckweed
is transferred or spread by humans and wildlife (ducks, geese, turtles,
etc.). It can quickly spread and cover an entire pond, blocking
sunlight for other plants and causing an unappealing pond. Common
treatments are with a diquat (contact herbicide) which turns duckweed
brown on contact or fluridone (non contact herbicide) which turns
the duckweed white. Grass Carp will also eat duckweed.
(Wolfnia spp.) is smaller than duckweed and looks like small green
seeds with no roots that hang below. Watermeal will feel gritty
between your hands and fingers. Watermeal can be spread by humans
and wildlife into new areas. It can also spread quickly and cover
an entire pond blocking sunlight and causing an unappealing pond.
Common treatments are with a diquat (contact herbicide) which turns
duckweed brown on contact or fluridone (non contact herbicide) which
turns the duckweed white. However, watermeal can be more difficult
to treat than duckweed.
Water Lilies (Nymphaea odorata) are a great example of
beauty in moderation. Lily pads can greatly enhance the beauty of
a pond or water garden with the green pads and the flowers, but
they can also quickly overtake a pond if not monitored. They can
be held in check by simply pulling the pads out. They have rounded
leaves about 6-12" with a cleft or cut to the center. The underside
is a purplish red color. A white, fragrant flower is also produced.
Hyacinth (Eichhornia crassipes) is an invasive plant species
that originated from Brazil. It can quickly spread and take over
an entire pond; therefore, it is often classified as undesirable.
It is characterized by the prominent purple flower. The upper petal
of the flower has a yellow spot surrounded by purple. If this species
is in your pond, it is important to keep it from spreading too rapidly
with treatment or pulling the plants out.
(Brasenia schreberi) has floating lobed leaves similar to the Fragrant
Water Lily, but without the cleft and the leaves are much smaller,
typically only about 4" long and 3" wide. The stem and
undersides of the leaves are purple and are covered with a thick,
gelatinous coating. This can be a desired species depending on personal
taste and if it has not overrun the pond.
(Nuphar polysepala) is another rooted plant with floating leaves
and flowers. Yellow, ball shaped flowers bloom during the summer
months. The leaves are large (12") and can be round or heart
shaped with rib down the center and a cleft. It is a great species
for fish and wildlife because it serves as a food source and habitat.
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is a plethora of submerged aquatic plant species. Some may be more
prevalent in certain areas than others. Submerged aquatic vegetation
are plants that are completely under the water and typically have
a root system in the bottom sediment. They require the water for
physical support of the plant structure.
difference between desirable submerged aquatic plants and undesirable
varieties is personal taste (how the plants look) and balance. A
beautiful plant that takes over the entire pond can quickly turn
from one that is pleasant to one that needs to be killed off. Keeping
plant species in check and in balance will create a beautiful pond
setting. Below are some common submerged aquatic plants and some
information about them. This section of the page is an ongoing process,
so check back for more additions.
(Chara spp.) is actually a form of erect algae. It is a
great plant for ponds with excessive nutrients because it uses up
a large amount of nutrients and provides food and hiding for fish
and other organisms. It can look like several other aquatic plants,
but a way to tell it apart is to break the thin straw-like stem.
Since it is a single celled stem, if you break it, the entire stem
will turn flaccid. Other plants will just break or bend, not turn
flaccid. Also has a strong garlic smell to it. As with many plants,
it is good in moderation. The pond above is a bit over grown.
(Potamogeton) is a thin leafed aquatic plant that is native
to many areas. This plant can serve as a food source and hiding
place for organisms in your pond and produce oxygen. Since it is
native, it is not as invasive as non native plants, but it must
be kept in moderation. This picture is of young pondweed before
it puts out is surface leaves. Some consider pondweed as a floating
plant due to these surface leaves.
Watermilfoil (Myriophyllum spicatum) is not native to the
US and is an extremely invasive species. There are strict regulations
for boats in lakes that contain eurasian watermilfoil because small
pieces that break off can stick to boats and trailers and then re-root
in other bodies of water. The leaves are feather-like and are limp
when out of water. The leaves are arranged in circles of 3 to 5
around a long, spaghetti stem. The plants can grow over 10' tall.
The tops of the stems often are reddish in color.
(Utricularia purpurea) is an aquatic plant that can live in ponds
with limited nutrients available. It is actually a carnivorous plant.
It can look like an unorganized mess in your pond, but it eventually
comes together to form the "starfish" shape and then shoots
up the yellow flowers. Black bladders hang below that open and catch
small organisms like zooplankton. Bladderwort can be a pain if it
takes over your pond and since it isn't as dependent on nutrients
in the pond, it can spread rapidly.
(Hydrilla verticillata) is an undesirable aquatic plant with long,
branching stems. Hydrilla often fragments and form large floating
mats. It produces tiny white flowers in early fall. It can be differentiated
from Elodea or Egeria with its sharp toothed leaf margins. Hydrilla
feels brittle to the touch. Hydrilla can grow in shallow or deep
water and can quickly spread throughout a body of water.
Waterweed (Egeria densa) is branched and has a long, narrow
stem with dense leaves found in whorls of 4. The leaves can be oblong
or linear and are very fine toothed. It produces flowers that are
white with yellow anthers. As with many aquatic weeds, it needs
to be controlled to prevent overtaking your pond.
(Elodea canadensis) is commonly confused for hydrilla or egeria,
but is much smaller in size. The leaves are bright green, in whorls
of 3, and elliptic to oblong. Small white flowers are produced from
mid summer to fall. Needs to be kept in check to limit spreading.
(Ceratophyllum demersum) is a submersed aquatic plant, but does
not have any root structure. The feathery, fan shaped leaves are
arranged in whorls with small teeth and resembles a raccoon tail.
Coontail can grow very tall (15') and occur in deep water areas.
Controlling the spread of coontail can be difficult since it is
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aquatic plants grow in shallow areas, usually along the banks of
ponds or lakes, or in shallow marshy areas. Some may not be considered
aquatic vegetation, but can survive in wet soils for an extended
period of time. Emergent plants, unlike submerged vegetation, are
rigid and can stand on their own, without support from the water.
again, can be desirable or undesirable depending on balance and
what you like to see. Often times, emergent vegetation can be very
beneficial as a nutrient buffer. They can block or at least slow
down nutrients that are entering the pond due to runoff. Emergent
vegetation also serves to stabilize the shoreline and reduce erosion.
Deep rooted vegetation keeps the shoreline intact. Desirable varieties
also provide wildlife food and habitat. Below are some common submerged
aquatic plants and some information about them. This section of
the page is an ongoing process, so check back for more additions.
Rush (Pontederia cordata) is a plant that is often sold
in watergarden stores that sell aquatic plants. It produces a nice
purple flower and is great for the banks of ponds and watergardens.
It will use up and block some of the runoff nutrients entering the
pond and look good doing it.
(Typha spp.) are probably the most recognizable plant in and around
water. The tall stalks or stems with long, green leaves are very
recognizable and the 6-8" brown cylindrical spike produces
seeds for reproduction. Cattails can spread quickly if not controlled.
Cattails serve as cover for wildlife and also as a food source for
aquatic rodents, such as Muskrats.
(Syngonium spp.) is named after the "arrowhead" shaped
leaves. There are several species within the arrowhead family. The
white flowers are in whorls of 3 with a yellow center. Arrowhead
is a good plant to use up nutrients, but need to be kept in check
to prevent over population.
Moss (Mayaca fluviatilis) is typically found in wetlands
or wet areas around ponds in creeping mats. It is a small, dark
green, branched plant with leaves spirally arranged on the stem.
Small pick flowers are produced with 3 petals. It can serve to block
runoff nutrients from entering the water.
Primrose (Ludwigia spp.) can be emergent or submersed plants,
depending on the species. It produces stems that grow horizontally
with roots that are wiry. Leaves are produced and alternate along
the stems. Erect stems occur during the flowering stage and most
typically bloom from April to September, depending on species and
location. Water primroses are typically considered desirable aquatic
(Eleocharis spp.) cover a wide range of species. Most grow in moist
soil or shallow ponds, marshes, and wetlands. The stems are topped
by a terminal spike. Spikerushes can cover many acres and serve
as cover for certain wildlife. Certain species of spikerushes are
used as a food source for birds and animals, as well as for human
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and mechanical treatments can often be the simplest and very effective,
but also are time consuming and can require a lot of physical effort.
This can be done with a rake or shovel or your bare hands. This
technique works well near the shoreline and in shallow areas and
works great at removing the weeds. This is also a good maintenance
technique. You can selectively remove individual plants to keep
them from overrunning your pond. Desired species can be held in
check with selective harvesting before they become an undesirable
is also harvesting equipment available that can remove more weeds
in less time and is also more effective in slightly deeper water
where hand removal is difficult, still only effective in the 6'
range. This method is also much less selective than hand removal.
This equipment varies in size and scale. Some is available for individual
use in small ponds, other are large barges that harvest the plants
with cutters, conveyors, and a large platform to store them.
way you physically or mechanically remove the plants, you must make
sure to remove all the plant fragments from the pond. Many of the
aquatic plant species can re-root and grow from small segments.
Therefore, cutting, but leaving fragments behind, will lead to more
growth in the future and the plants can spread into a larger area
of the pond. It is also important to remove the plants away from
the pond far enough to prevent them from washing in or getting blown
back in. Physically removing the plants is a great way to remove
large amounts of nutrients as well, which will improve overall pond
health in the future.
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are several chemical treatment options available for aquatic plant
problems. Some treat certain aquatic plants better than other treatments,
and since there are many types of aquatic plants, it is a good idea
to talk with a local lake management professional to get some assistance
in identifying the type of aquatic plant problem and develop a plan
for the best solution to that problem. Typically, liquid treatments
are more effective in shallow applications of 5 to 6' or less and
granular applications are better in deep water. Granular applications
can also be used in spot treatment. Some common chemical treatment
methods are copper products, diquat herbicides, and fluridone herbicides.
- Copper is usually the first answer most people get when they bring
up the subject of algae and control. Copper is toxic to certain
species of fish within the minnow family as well as salmonids depending
on the dosage and water chemistry. Water with high hardness and
alkalinity buffers copper from being toxic, but also limits its
effectiveness. The most common form of commercially available copper
is granular copper sulfate. Its effectiveness and cost as a broad
spectrum controller of planktonic and filamentous algae has led
to its high usage. Liquid chelated copper products are used to control
a broad range of algae including planktonic, filamentous, and bottom
attached types of algae. Cutrine-Plus® is an example with application
rates from 0.6 to 1.2 gallons per acre-foot of water treated. Consistent
usage of some copper products can lead to bioaccumulation within
the sediments and this approach is on the radar of some regulatory
agencies, so a varied approach is probably the most sensible path
Herbicide - Diquat is a liquid, contact herbicide that
is sprayed on the vegetation. This is a very powerful and fast acting
form of aquatic weed and algae control. The treated vegetation will
quickly die and turn brown from this treatment. A common diquat
herbicide brand is Reward® and is great for floating aquatic
vegetation. It is safe to use, according to the label, for algae
and floating aquatic vegetation control in natural ponds, but there
are restrictions concerning fish harvesting. A lake management professional
will be able to assist with information and application of this
Herbicide - Fluridone is a liquid, non contact herbicide
that is slower process than the diquat herbicide, but does not have
the same restrictions for water usage afterwards. Fluridone herbicide
is sold under the product name of Sonar® and manufactured by
Avast® and typically takes 30 to 90 days to effectively work.
The herbicide is absorbed into the plants and symptoms develop within
1 to 2 weeks. Affected plants will lose their green pigment and
turn white. This can be a more selective method of treatment depending
on application levels.
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can be used to help control and prevent aquatic weed growth in ponds.
Biological treatments may not work as fast as chemical treatments,
but can be effective and a long term solution to problems. This
method works better in smaller scale applications and it is important
to contact a lake management professional before introducing organisms
into your pond because you could see negative effects from this.
Some common biological treatments are other plant species, plant
eating fish, and bacteria.
Plants - Often times introducing more desired species
of plants can assist in helping rid the pond of a nuisance species.
Native plants are usually a good bet because they have more checks
and balances with the local environment. This can be difficult because
invasive species are often present because they can successfully
out compete desirable plants. This method works better when the
invasive plants are removed.
Eating Fish - Introducing plant eating fish, or herbivores,
can assist in limiting plant growth. Grass Carp are being used to
help control aquatic vegetation. They are bred to be sterile so
they will not reproduce in the pond and will eat vegetation in the
pond. Grass Carp do not like all forms of vegetation and there are
various restrictions on their use, so consult a local professional
or regulatory agency. They also do not eat algae, contrary to popular
belief, so they can shift your pond from aquatic plants to algae
- Bacteria and fungi can be used to help control aquatic plant growth.
Certain varieties of bacteria and fungi live on various aquatic
plants and can be used to selectively control aquatic vegetation.
The attacked aquatic plants will die from the introduction of the
bacteria and fungi and the more desirable plants will be unharmed.
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the pond environment can be an effective solution to aquatic plant
problems. Changing the habitat the aquatic plants grow in can de
detrimental to their health and cause reduced numbers or even elimination
of a certain plant species. This can be done changing the water
level, flushing the water, shading, changing the water pattern,
Level - Altering the water levels in a pond can have
a negative affect on aquatic plant health because many species grow
best in certain water level conditions. If water levels are raised,
sunlight may not be able to fully penetrate the water column and
submerged vegetation will die due to the lack of sunlight. Conversely,
if the water levels are dropped, the sunlight and air can dry out
areas along the edges that are now not covered by water. Without
water contact the plants will die off and the sunlight will burn
off the remaining vegetation. In my own experiences at a trout farm,
ponds were periodically drained and cleaned; however, filamentous
algae would still cling to rocks, aerators, and cages. A few days
in the sun without water would burn the algae off and the pond would
be new once filled again. Altering the water level can be a large
project and some ponds that have a drain installed and constant
water supply make this much easier.
- Flushing the water can have two benefits. First, flushing out
the nutrient filled water with nutrient free water will lower the
overall nutrient content in the water and help reduce the existing
plant growth and help prevent future growth. Flushing can also be
used to remove floating aquatic plants such as duckweed and watermeal.
Again, in my own experiences, a small pond that was covered with
duckweed was overfilled. The water level was raised a couple feet
above normal level by covering the overflow. The overflow was then
removed and much of the duckweed was washed into the marshy overflow
area and out of the pond. This can also be a very intensive and
large undertaking. A large clean water supply and overflow to the
pond makes this process much easier.
- Since the aquatic plants require sunlight for the photosynthesis
process, limiting the amount of sunlight that reaches the water
can decrease the amount of aquatic plant growth. This can be done
with trees and shrubs naturally, or done through artificial shading.
Another personal experience at the above mentioned trout farm had
a side benefit for the aquatic plant problems. Several raceway ponds
were shaded with a shade cloth to limit predation of fish by Great
Blue Herons and King Fishers and also to help keep the water cool
during the hot summer months, since Rainbow Trout require cold water
to grow. A side benefit was the reduced aquatic and terrestrial
plant growth. The water did not receive as much sunlight penetration
and the aquatic weeds did not grow as fast or dense in these areas.
The grasses around the pond also grew slower, which was not a problem
for those unlucky enough to be selected for pond mowing.
Patterns - Altering the water patterns can have an
effect on aquatic plant growth. Many of the undesirable aquatic
plants that overtake a pond thrive in shallow, stagnant water. By
changing the stagnant water into a moving, riverine environment,
those same aquatic plants struggle to grow and survive. This process
can be difficult and is best done with the addition of equipment.
Kasco's Water Circulator was designed for this purpose. It creates
directional flow and a riverine environment out of a stagnant pond.
By adding a Water Circulator, you can successfully limit the amount
of aquatic plants because they cannot thrive in moving water areas.
- Dredging is physically digging or removing sediment from the pond
to make the pond deeper and remove organic, nutrient rich sediment
from the pond, as well as the plants that are growing in that sediment.
This can be a very intensive and expensive project because of the
heavy equipment involved and the removal of the sediment, but is
very successful. Dredging makes the pond deeper, thus increasing
the water column. Deeper water has a more difficult at supporting
plant life because not as much sunlight can reach the bottom. Dredging
also removes much of the nutrients in the pond and the plants that
are living in those sediments, thus renewing your pond or making
it younger (see Backyard Ponds
& Lakes). It is extremely important to remove the sediment
far away from the pond so the water and nutrients to run back in
or get washed in with a large rainfall.
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is an integral part of your entire pond ecosystem and is also a
tool to effectively manage aquatic plant growth. The most important
benefit of supplemental aeration in your pond is buffering against
aquatic plant die off. Aeration can also help with limiting the
amount of plants that grow by limiting sunlight penetration and
the breakdown of nutrients.
discussed previously on the page, there are many types of aquatic
plants that can be a nuisance to you and your pond. There are several
effective ways of treating these problems, whether it is biological,
physical, changing the pond environment, or chemical treatments.
Chemical treatments are very popular because the require less effort
than physical removal of the plants, work faster than most biological
treatments, and are not as large of a project as changing the pond
environment. The chemicals will kill off the aquatic plants and
be fairly effective in doing so.
the plants start to die off is when aeration is needed. The dead
plant material will begin to be decomposed by bacteria on the bottom.
The decomposition process can occur aerobically (with oxygen) or
anaerobically (without oxygen). As long as there is oxygen available,
it will take place aerobically. This is good because aerobic decomposition
is faster and creates less harmful byproducts of the process. However,
the process uses up a lot of the available dissolved oxygen in the
water, much faster than can be naturally added in most cases. Once
the oxygen is depleted, decomposition switches to anaerobic and
without oxygen fish and other aquatic organisms die.
supplemental aeration in a pond before, during, and after will help
mix the water column, and with some chemicals, increase their effectiveness.
After the treatment, the added oxygen will allow for aerobic decomposition
to take place and provide enough dissolved oxygen for your fish
to survive during the process.
agitation caused by an aeration device is also important in the
battle with aquatic plants. Creating water movement and waves helps
eliminate stagnant water areas where aquatic plants thrive. The
agitation also helps refract some of the incoming sunlight, limiting
the amount available for the plants.
and agitation is also very important in what it takes out of the
pond. As discussed, during the aerobic decomposition process, oxygen
is used. A byproduct of this process is carbon dioxide, which is
a key component to plant growth and is used during photosynthesis.
The surface agitation caused by aeration breaks up the water by
splashing. This provides amply surface area of the water droplets
to "vent" the carbon dioxide. Carbon dioxide levels in
the water can be much higher than the air, therefore, when the water
is exposed to the air, the carbon dioxide will leave the high concentration
area of the water to the lower concentration area, air. Some nutrients
in the water are also volatile and can be vented when the water
is exposed to the air. Kasco Marine offers several options for adding
oxygen to the pond, creating water agitation, and water movement.
Kasco's Pond Aerator models are great for adding oxygen when no
display pattern is needed. These units splash the water creating
great agitation while adding oxygen. The Aerating Fountain models
add oxygen and aeration, while providing a beautiful display in
your pond. Kasco's Water Circulators can turn your stagnant pond
into more of a riverine environment which can limit the growth of
some aquatic plants.
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These pages are reprinted from www.gotalgae.com, courtesy