Duckweed
is an agressive pond weed that covers a pond quickly with a green scum.
Duckweed
(Lemnaoideae) is something I am actually very fond of...of course when a
large pond is infested with this plant it is no fun but in smaller water
gardens and backyard ponds duckweed can actually be a helpfull addition
to the ecosystem!
Myself, I've
actually gone to the garden store and bought a container full of
duckweed to add to my backyard pond...it cost me $5 and my wife
asked me if I was losing my marbles because duckweed can be found
in almost any farm dugout or stagnant swamp in the area!
I am asked at least twice a week about methods for controlling duckweed
and other aquatic plants and algae of course.
In a large pond duckweed can be an invasive plant that can cover
the surface quickly and it often is a real nuisance for the pond
owner who suddenly can't see anything in the pond!
Before we kill the duckweed with an aquatic herbacide, yes there
are some good algaecides that can eliminate duckweed from a pond,
lets make sure we actually do want to do it because this floating
plant is actually a real wonder of the pond!
Duckweed can absorb a whole bunch of nutrients from the water and
will provide a great umbrella of shade for fish...so it will keep
waters cooler and also suck out phosphates from the pond. These
phosphates and other nutrients are the junk in the pond that cause
the big blooms of floating green algae and algae that grows on the
bottom of the pond.
Why
You May Love Duckweed:
Duckweed is a small delicate plant that drifts on the pond surface,
filling in spaces between the lily pads, creating a lovely green
blanket across the pond. This provides a lush habitat for frogs
and fish and insects of the pond.
The layer of
floating aquatic plants provides shade to the pond keeping it cooler
during stifling hot days of overhead sun. Waterfowl will feed voraciously
on the duckweed thus nest nearby and live in the pond.
Duckweed grows rapidly and absorbs mineral elements like nitrogen
and phosphates from the water column so it can be an important part
in the aquatic rehabilitation of any pond or lake as these nutrients
can cause problems like algae and cyanobacteria. It is especially
good at removing ammonia from ponds.
Beyond providing shade for fry bluegill and a place to live for
bullfrogs the duckweed helps reduce evaporation which can be a problem
in a clear pond without any cover to slow the rate of pond evaporation.
Sometimes just the rich green color of the plant alone is enough
to make us feel like our pond is a healthy and natural aquatic system!
A bit like a stained glass window on the pond, duckweed is a wonderful
and beautiful plant, that with a bit of understanding and acceptance
is actually a very beautiful thing!
Why You May Hate Duckweed:
Duckweed is an invasive and agressive aquatic weed that can rapidly
multiply and if conditions are right will completely cover a pond
with a thick green cover of tiny green plants that are only a few
milimeters in size.
The thick matting of pond weed can literally choke out a pond and
if conditions, temperatures and nutrient levels are right can completely
hide the water and create a cover that hides the pond and makes
it almost unpleasant. Frogs and ducks and turtles will live in what
looks like a swamp! Maybe it provides food for swans and geese and
a mallard duck or two but it can choke out oxygen levels.
Two Ways of Getting Rid of Duckweed
Well, actually you could just ignore the duckweed and live with
the problem! So that means there are three options for this aquatic
plant. Adding natural bacteria to control muck and nutrients will
assist in slowly reducing the amount of food available for this
aquatic floating bugger. The beneficial bacteria, over time, will
have an impact on the amount of duckweed in your pond...but it can
be a long process and manual removal will greatly help this process.
So basicially, beyond ignoring it you have two ways to deal with
duckweed:
1
- The Chemical Way
Fluridone
Fluridone is the most effective and cost-efficient
treatment you can buy for the selective, long-term control of undesirable
weeds.
Fluridone is available in formats of 4 ounces up to 1 gallon
Weeds Controlled Duckweed, Salvinia, Watermeal, American PondWeed,
Bladderwort, Clasping-leaf Pondweed, Coontail, Curly-Leaf Pondwed,
Elodea, Eurasian Watermilfoil, Fanwort, Flat-Stemmed Pondweed, Floating-Leaf
PondWeed, Horned Pondweed, Hydrilla, Large-Leaf Pondweed, Naiads,
Sago Pondweed, Small Pondweed, Variable-Leaf Watermilfoil.
How to Apply Fluridone
Fluridone manages undesirable aquatic vegetation
and is recommended for use in water bodies with soft or muck bottoms.
Fluridone is easy to apply and just one application will provide
season-long enjoyment of your pond.
Fluridone can be applied in early spring, at the first sign of weed
growth, through midsummer. Pond Level Best control is obtained when
discharge can be stopped for thirty days or longer.
Pond levels should be at or near normal when water level when treated.
Excessive outflow dilutes Fluridone and reduces the chance of control.
Dose The typical dose of Fluridone is one (1) quart per surface
acre with an average of depth of 4-6 feet. Use 1.5 quarts per surface-acre
for watermeal.
Control Time
Plants should start turning white as control begins
in 15 to 30 days. It may take 30 to 90 days for final results.
This slow rate of control is beneficial as it greatly decreases
the chance for a severe change in oxygen levels which can harm fish.
Active Ingredient 41.7% Fluridone (Substitute for Sonar® AS).
Cannot be shipped to: AK, CA, CT, DC, HI, ME, NJ, NY, PR,
RI, VT, WA or Canada
Easy Application: simply mix in a bucket
of pond water and pour in directly from shore. Allow 30 - 45 days
for best results Great for entire bodies of water but not meant
for treating a portion of a pond or lake Stays suspended in the
water for longer control
Sonar® Aquatic Herbicide

Sonar ready-to-use RTU
represents an exciting new era in pond weed management for the do-it-yourselfer
the innovative new RTU formulation allows anyone to make water usable
for recreation, bring fish populations back into balance and restore
property values.
We're so sure that applications of sonar RTU conducted according
to directions will control target aquatic vegetation listed on the
label that we'll work with you until you see the results you expect.
There's never been a better time to trust your lake or pond to sonar.
Sonar RTU and duckweed many pond owners consider duckweed to be
their toughest aquatic weed problem. Duckweed is a very comma on
nuisance aquatic weed that is spread from pond to pond via waterfowl
or other wildlife.
While it is comma only mistaken for algae, duckweed is actually
a tiny plant with an explosive reproductive capacity that can completely
cover a pond in just a few weeks to the point that the infested
waterbody resembles a golf-course green.
Fortunately, no other aquatic herbicide is more effective on duckweed.
Sonar provides complete, long-lasting control of duckweed and other
stubborn unwanted aquatic vegetation.
Aquatic
herbicides and pond weed killers
 
Aquatic algaecides and herbicides are very effective at controlling
duckwweds and other unwanted invasive pond species. You should understand
that such algae problems, well...it's not reaslly an algae but an
aquatic weed plant, if they are treated with herbiceds can lead
to a dependance or resistance and scientists generally agree that
chemical selection pressure that is applied applied to aquatic weed
populations for a long enough period of time eventually leads to
resistance. This means that while the chemical pond weed killer
may work quickly and effectively for the first few years, unless
you are adding a positive treatment with aeration and natural beneficial
bacteria you will just be "chasing the dragon" so to speak!
2
- The Natural Way
Natural
bacteria for ponds
If the pond is small enough just the best way to remove the small
little flowering plant known as duckweed is to use a fine meshed net
and just manually remove it day by day, hour after hour, until there
is none left. Of course it is really tough to completey eradicate
the problem but you can keep it under control just like keeping the
dandelions out of the vegetable garden!
You need a net with a long handle or a good quality aquatic rake to
harvest this pond weed if you want to deal with this problem naturally
or of course you can invite a family of ducks or geese or swans into
your pond and they will love the free food supply offered by these
floating flowering plants but you will still need the manual removal...if
you don't want to accept the duckweed or don't want to perform the
manual work or invite the Duckworth family into the pond then you
need to go to the next option..
WhiteCap®
selective herbicide
White Cap Selective Herbicide Control aquatic weeds and grasses in fresh
water ponds, lakes, and drainage/irrigation canals with WhiteCap™
SC selective herbicide, a proven reformulation of the popular active
ingredient fluridone. WhiteCap effectively controls a wide range of
floating, submersed and emersed aquatic vegetation, including Duckweed,
Hydrilla, Bladderwort, Watermilfoil, Naiad, Elodea, Water-lily, Pondweed,
and Coontail See
The List of Aquatic Weeds that White Cap SC will control before you
buy. Email us if you're not sure.
Susceptible
aquatic weeds absorb WhiteCap SC through the shoots and roots. For
effective control, contact of WhiteCap with the target plant must
be maintained for at least 45 days. Effective control is reduced
if conditions exist that dilute the concentration of WhiteCap in
the water to below labeled rates.
Apply WhiteCap as a surface spray or subsurface injection at rates
between 10 and 90 ppb for single applications, or if multiple applications
are made, do not exceed 150 ppb per growing season.
Water treated with WhiteCap SC at rates greater than 5 ppb must
not be used for irrigation of certain crops and newly seeded turf.
If the concentration of WhiteCap is less than 10 ppb, established
tree crops, established row crops or turf can be irrigated with
WhiteCap treated water.
Do not apply WhiteCap at rates greater than 20 ppb within ¼ mile
of any functioning potable water intake.
WhiteCap effectively controls a wide range of floating, submersed
and emersed aquatic vegetation, including Hydrilla, Bladderwort,
Watermilfoil, Naiad, Elodea, Water-lily, Pondweed, Coontail and
Duckweed. Selective control.
At low use rates, it is safe for most native beneficial aquatic
plants; WhiteCap SC selectively removes the nuisance plants, while
having little impact to desirable species. Low
use rates provide for cost-effective aquatic plant control.
Complete control.
Readily moves and disperses throughout the water column, providing
complete and thorough control of target nuisance aquatic weeds Slow
control. Works slowly to remove excessive aquatic weeds with minimal
impact to aquatic ecosystems No human or livestock use restrictions.
Water treated is potable water safe and may be used immediately
for human recreation and for watering livestock.
Average
Water Depth of Treatment in Feet
|
Fluid
ounces per acre
to achieve desired herbicide concentration
|
Application
Directions
|
45
ppb
|
90
ppb
|
1
|
3.8
oz.
|
7.7
oz.
|
ApplyWhiteCap
to the entire surface area of the pond.
Single Applications: Use the amount of WhiteCap
listed to give 45 to 90 ppb .fluridone in treated water.
Higher rates should be used for dense weed infestations,
for dif.cult-to-control species, and for smaller ponds
(less than 5 acres in size and average water depths of
less than 4 feet). Split or Multiple applications:
Use when dilution of the treated water is likely to occur.
Do not exceed 90 ppb per annual growth cycle. |
2
|
7.7
oz.
|
15.7
oz
|
3
|
11.8
oz.
|
23.4
oz.
|
4
|
15.7
oz.
|
31.4
oz.
|
5
|
19.5
oz.
|
35.0
oz.
|
6
|
23.4
oz
|
46.7
oz.
|
7
|
27.2
oz.
|
54.4
oz.
|
8
|
31.4
oz.
|
62.4
oz.
|
9
|
35.2
oz.
|
70.1
oz.
|
10
|
39.0
oz.
|
78.1
oz.
|
|
Vascular
Aquatic Plants Controlled by WhiteCap
|
Floating
Plants
|
Emersed
Plants
|
Submersed
Plants
|
Shoreline
Grasses
|
common
duckweed
(Lemna minor)
|
spatterdock
(Nuphar luteum)
|
bladderwort
(Utricularia spp.)
|
paragrass
(Urochloa mutica)
|
|
water-lily
(Nymphaea spp)
|
common
coontail
(Ceratophyllum demersum)
|
|
|
common
elodea
(Elodea canadensis)
|
egeria,
Brazilian elodea
(Egeria densa)
|
fanwort,
cabomba
(Cabomba caroliniana)
|
hydrilla
(Hydrilla verticillata)
|
naiad
(Najas spp.)
|
pondweed
(Potamogeton spp., except Illinois pondweed)
|
watermilfoil
(Myriophyllum spp., except variable-leaf milfoil)
|
|
Suggested bApplication Rates For Duckweed
75' x 75' Pond (.13) Acre 4 ft avg depth. - Amount required: 2 -
4 ounces
105' x 105' Pond (.25) Acre 4 ft avg depth. - Amount required: 4
- 8 ounces
148' x 148' Pond (.50) Acre 4 ft avg depth. - Amount required: 8
- 16 ounces
208' x 208' Pond (1.0) Acre 4 ft avg depth - Amount required: 16
- 32 ounces
Duckweed
Information Websites
Here
are some websites we recommend if you are looking for more information.
Washington State Department of Ecology
http://www.ecy.wa.gov/Programs/wq/plants/pla
ntid2/descriptions/lemmin.html
Lemna minor (lesser duckweed) and Lemna trisulca (star duckweed) Duckweeds
are among the world's smallest flowering plants. Individual lesser
duckweed plants are tiny, round, bright green disks, each with a single
root.
USDA.gov
http://plants.usda.gov/java/profile?symbol=LEVA
PLANTS Profile for Lemna valdiviana (valdivia duckweed) | USDA PLANTSA
PLANTS profile of Lemna valdiviana (valdivia duckweed) from the USDA
PLANTS database.: Kingdom Plantae – Plants Subkingdom Tracheobionta
– Vascular plants Superdivision Spermatophyta – Seed plants Division
Magnoliophyta – Flowering plants Class Liliopsida – Monocotyledons
Subclass Arecidae Order Arales Family Lemnaceae – Duckweed family
Genus Lemna L. – duckweed Species Lemna valdiviana Phil. – valdivia
duckweed
Wikipedia
http://en.wikipedia.org/wiki/Lemnaoideae
Lemnaoideae - Wikipedia, the free encyclopedia 24 May 2009 ... Duckweed
is an important food source for waterfowl and are eaten by humans
in ... Classification of the duckweeds in the family Lemnaceae is
... en.wikipedia.org/wiki/Lemnaoideae - Cached - Similar - Lemna -
Wikipedia, the free encyclopediaLemna is a genus of free-floating
aquatic plants from the duckweed family. .... Lemna Ecotox testing
Duckweed growth inhibition tests and standardisation ...
Guppies.com
http://www.guppies.com/forums/showthread.php/duckweed-and-waterquality-18686.html
Duckweed and waterquality... a blessing in disguise. In fact, duckweed
does much more than suck up every particle of Nitrate in your tank.
In depth study will reveal that duckweed attacks ammonia vigorously,
as well as Nitrates, Nitrites and just about any other molecule with
the nitrogen atom in it, lol. In addition to that, duckweed sucks
up phosphorus like a thin milkshake, actually removes suspended solids,
and organic material and even other toxins!. As if that weren't impressive
enough, it produces oxygen like nobodies business!
Homemade Duckweed Skimmer
http://forums.pondboss.com/
If you are looking for a homemade duckweed skimmer then we saw on the PondBoss
Forums of a fellow who used a "prickly rope" that he rigged up
using a simple nylon rope and zip-ties to create an ingenious pond skimmer
system that basically corrals the duckweed and traps it in the circle of
the "prickly rope" where it can be easily removed. You have to
see it to believe it and I bet it works too! |