Front Cover
 Table of Contents
 Site selection
 Pond construction and methods of...
 How to use the appendices
 Appendix 1. Aquatic weed ident...
 Appendix 2. Herbicides
 Appendix 3. Agriculture chemical...
 Appendix 4. Conversion factors...
 Back Cover

Group Title: Circular Florida Cooperative Extension Service
Title: Weed control in aquaculture and farm ponds
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00084496/00001
 Material Information
Title: Weed control in aquaculture and farm ponds
Alternate Title: Circular 707 ; Florida Cooperative Extension Service
Physical Description: 24 p. : ill. (some col.) ; 28 cm.
Language: English
Creator: Thayer, Daniel David, 1957-
Florida Cooperative Extension Service
Langeland, K. A.
Haller, W. T.
Joyce, J. C.
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 1990
Subject: Aquatic weeds -- Control -- Florida   ( lcsh )
Weeds -- Control -- Florida   ( lcsh )
Aquaculture -- Florida   ( lcsh )
Farm ponds -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: D.D. Thayer ... et al..
General Note: Cover title.
 Record Information
Bibliographic ID: UF00084496
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 15472077

Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Table of Contents
        Page 1
    Site selection
        Page 2
    Pond construction and methods of aquatic weed control
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
    How to use the appendices
        Page 9
    Appendix 1. Aquatic weed identification
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
    Appendix 2. Herbicides
        Page 17
        Page 18
        Page 19
    Appendix 3. Agriculture chemical toxicity to selected aquatic animals
        Page 20
    Appendix 4. Conversion factors and formulas for herbicide calculations
        Page 21
        Page 22
        Page 23
        Page 24
    Back Cover
        Page 25
Full Text

Circular 707

:tltral Science
JARN\ 10 i
' verily of Florid



D.D. Thayer, K.A. Langeland, W.T. Haller, and J.C. Joyce

Florida Cooperative Extension Service / Institute of Food and Agricultural Sciences
University of Florida / John T. Woeste, Dean

3 dc_

Mention of a tradename or a proprietary product does not constitute a guarantee or warranty of the product
by the University of Florida and does not imply its approval to the exclusion of other products that also may
be suitable. The University of Florida, Center for Aquatic Plants, has not tested all the herbicides mentioned
and there is no express or implied warranty as to the fitness of any product. Any product tradenames that are
listed are for the benefit of the reader and the list may -not contain all products available due to changes in
the market. Be sure to read and follow all herbicide label directions.

Weed Control in

Aquaculture and Farm Ponds

D. D. Thayer, K. A. Langeland, W. T. Haller, and J. C. Joyce

Table of Contents

Site Selection ........... ............................. ............... ... .... 2
Pond Construction ........... ...................................................... 3
Methods of Aquatic Weed Control
Fertilization ...................................................... ......... 3
Drawdown.. ............................................... 4
Mechanical Control ............ ................... ............................. 4
Biological Control ............................................................... 5
Insects and Plant Pathogens ................... ................................. 5
Herbivorous Fish ................................... ......................... .. 6
H erbicides ............................................................. 6
Herbicide Selectivity ............................................................. 6
M ode of A action .......... ..... ........................................ ....... 6
Herbicide Formulation ............. ................... ........................ 7
Adjuvants ........................... ............................... 7
The Label ............................................................. ..... 7
Precautions with Herbicides ................................... .................... 8
How to Use the Appendices ............. ................... ...................... 9
Appendix 1: Aquatic Weed Identification ............................................. 10
Appendix 2: Herbicides .....................................................17
Appendix 3: Agricultural Chemical Toxicity to Selected Aquatic Animals ................... 20
Appendix 4: Conversion Factors and Formulas for Herbicide Calculations.................... 21

D.D. Thayer is currently Director of the South Florida Water Management District, Aquatic
Plant Management Division. K.A. Langeland, Associate Professor of Agronomy, W.T. Haller,
Professor of Agronomy, and J.C. Joyce, Professor and Center Director, are with the Center for
Aquatic Plants, IFAS, University of Florida, Gainesville.

Cover photo by David L. Sutton, Center for Aquatic Plants, University of Florida, Fort Lauderdale.

Many times, farmers and other landowners en-
thusiastically decide to build a fish pond to supple-
ment farm income via fish production or for personal
enjoyment. Soon after the pond is constructed,
unforeseen problems begin to arise. One major prob-
lem that occurs is that the pond becomes clogged
with aquatic plants. The level at which an aquatic
plant becomes a weed problem depends on the pond's
intended use. A farm pond used primarily for week-
end fishing can tolerate considerably more vegetation
than a pond constructed specifically for fish produc-
tion and/or irrigation. Shoreline grasses can help
stabilize and prevent bank erosion, but out of control,
grasses may encroach into the water, where they
restrict access and usability. This circular provides
information on aquatic weed identification and control
for farm and aquaculture ponds.
Prevention is the best technique for reducing
takeover by aquatic weeds. It's easier and more
economical to prevent potential weed problems than
it is to cure them. Preventive measures include
proper pond location and construction.

Site Selection
The location in which you dig a pond can be an
important decision when it comes to preventive
control. Proper location can help minimize erosion
and nutrient enrichment from the runoff of silt and
inorganic and organic fertilizers that decrease the
lifespan of the pond and limit its usefulness.
Whether you fertilize your pond for fish produc-
tion or avoid intentional nutrient enrichment, sites
near fertilized fields, feedlots, barnyards, septic tanks,
gardens, roadways, or other sources of runoff should
be avoided. Agricultural and domestic runoff such as
from parking lots and roadways may also contribute
heavy metals, oils, and pesticide contaminants. If an
"ideal" pond location cannot be found, a berm to

Fig. 1. A swale and berm system slows down stormwater
runoff and traps pollutants before they reach the pond.

divert runoff away from the pond can be constructed
(Figure 1).
Avoid building a pond with a flowing stream
unless excessive water can be diverted. When a
fertilization program is being used for algae produc-
tion, the continual flushing action of a flowing stream
would be counterproductive, resulting in the use of
much more fertilizer to maintain an algae bloom.
Herbicide effectiveness may also be diminished when
a long contact period is required for underwater
plants. Aquatic plants growing in the stream itself
are much more difficult to control, even with the
faster acting contact-type herbicides. Without control
of water input, water quality in general will suffer
and become difficult to manage.

After considering the factors mentioned above,
select locations that have recommended watershed-
to-pond ratios if you don't have a well or other water
source. The USDA Soil Conservation Service (SCS)
recommends that, based on Florida's annual rainfall,
an excavated pond should be no less than 6 to 8 feet
deep (Figure 2), and that a drainage area of 2 to 3
acres is necessary to maintain one foot of water in a
one-acre pond (Figure 3). Experience with farm
ponds in North Florida indicates that deeper ponds
(10 to 20 feet deep) have fewer aquatic weed prob-
lems than shallower ponds. If a properly balanced
fish population is to be maintained, then at least one
surface acre of water is required. So, to build a one-
acre pond with an average depth of 8 feet, an average
16 to 24 acres of watershed would be required.

S.~ ::.~

~ ~2.

Minimum Pond Depth

' 6-7 feet deep

7-8 feet deep

b: :
i..'. ~l'::i
i. -'
c.. .d/

~? -,.;
'u;p ":`';

Fig. 2. Based on probable seepage and evaporation
losses, Florida ponds should have a minimum depth of
6 to 8 feet.


) .

Fig. 3. The watershed required for most of Florida would
be 2 to 3 acres of watershed to 1 acre-ft of water.
The surrounding vegetation cover, soil type, land
slope, and other land use characteristics will have an
effect on the degree of drainage. If the surrounding
vegetation is primarily woodlands, then more water-
shed is required than if the surrounding land is
primarily in pasture.
If possible, choose a location that maximizes use of
prevailing winds. Good water circulation is essential
for increasing dissolved oxygen in the water column,
cycling nutrients, increasing bacterial populations in
the hydrosoil, and restraining floating plants from
covering the pond.
If at all possible, avoid a location that will have
heavy livestock usage. If the pond is going to be used
primarily for watering livestock, divert water to a
watering trough or section off a portion of the pond
in order to prevent the livestock from wading in at
will (Figure 4). Livestock increase erosion, levee

destruction, organic pollution, and turbidity, as well
as disturb fish spawning areas. Restricting livestock
provides cleaner drinking water and will increase the
life of the pond. The cost of fencing will be more
than offset by the increased cost of pond main-
Pond Construction1
Pond banks should be as steep as possible along
the edges to a depth of several feet to avoid shoreline
vegetation from becoming established. They should
then gradually slope to a depth of 6 to 8 feet to the
pond center. Removal of brush and trees along the
edge will increase berm stability and reduce leaf and
branch litter. Grass species should be encouraged to
grow along the banks to prevent erosion and wash-
The construction of a small berm (Figure 1)
around the entire pond can be helpful in trapping
rainwater runoff that may be rich in nutrients and
suspended solids (leaf litter, trash, etc.). The water
that percolates through the berm into the pond will
be filtered rather than flowing directly into the pond
itself. Terracing adjacent fields can also be a valuable
method of decreasing both field erosion and sedimen-
tation. If your future plans include water drawdown
for pond reconstruction, now is the time to plan for
drainpipes, risers, valves, etc.

Methods of Aquatic Weed Control

The principle behind a pond fertilization program
is that phytoplankton (microscopic algae) populations
increase as a result of the controlled addition of
'Contact your local SCS office for specifications.

Fig. 4. Water is piped through the dam's drainpipe to a stockwater trough.


Bell tile around valve and
pipe for suitable housing

Fig. 5. The grass carp provides effective weed control
for most submersed and many floating weeds.

fertilizer nutrients until light penetration is reduced
below the level required for growth of submersed
Before you decide on fertilization for weed control,
consider the following. 1)Once a fertilization program
has begun, you must always continue the program or
face possible severe weed problems. 2) Particular
weeds, such as hydrilla (see "Submersed Plants" in
Appendix 1), have been shown in Florida to outcom-
pete phytoplankton communities for nutrients,
thereby making the weed problem worse. It is
therefore imperative that fertilization should not be
initiated until current weed infestations have been
totally controlled. 3) If the fertilization of a pond is
intended to be used to stimulate food production in
an aquaculture pond, then additional weed control
with herbicides or with weed eating carp Ctenopha-
ryngodon idella (see page 6, "Herbivorous Fish") may
be beneficial (Figure 5).
Phytoplankton is the base of the food chain.
Increases in phytoplankton will increase the produc-
tion of zooplankton, which ultimately increases fish
production. Most fertilization recommendations
suggest adding inorganic fertilizer every 2 weeks until
a shiny object placed 18 inches below the surface is
no longer visible (Figure 6). Once this level of phyto-
plankton is obtained, maintain that level with perio-
dic fertilization. The optimum pH should be at least
6.5 or higher, and liming may be required prior to
fertilization. The best time of year to begin a fertiliza-
tion program is in the spring before aquatic weeds
have begun growth. Once established, submersed
vegetation must be controlled either with chemicals
or grass carp or must be physically removed in order
to insure good algae production. Fertilization shortly
after a herbicide application may speed decomposition
resulting in oxygen depletion and should be avoided.

Fig. 6. Fertilization encourages production of phyto-
plankton that reduces sunlight penetration into the water.

Remember, if you desire clear water for swimming or
other recreational purposes, do not fertilize your

Water level fluctuation or pond draining can be
used very effectively if the conditions are favorable.
Exposing the bottom of your pond to the atmosphere
will solidify suspended mud and consolidate bottom
sediments to a watertight condition. Excessive nutri-
ents suspended in the water column will be diluted
as a result of the water exchange. In order to have
a successful drawdown, you must leave the water
level down long enough to desiccate and kill sub-
mersed plants. An incomplete drawdown may have
little to no effect, and some plant species that are
not susceptible to drawdown may spread into the de-
watered lake bottom more easily. Cattails are often
opportunistic and may establish during extended
drawdowns (Figure 7). The consolidation of bottom
muck by drying should also improve fish spawning
and nursery areas. Drawdowns also increase options
for chemical weed control. Some herbicides are only
labeled for use on drained pond bottoms and treat-
ments at this time often provide several years of
weed control because the herbicides are bound in the
bottom sediments.

Mechanical Control
Mechanical control involves the physical harvesting
of vegetation by hand or with specifically engineered
equipment. For the owner of a small pond, mechani-
cal control can be helpful for removing small popula-
2Consult an aquatic plant biologist before attempting a drawdown
for aquatic weed control to insure that weed problems can be con-
trolled in this manner.


Fig. 7. Cattails flourish in a pond that has been drawn
down to kill weeds.

tions of nuisance plants. For example, a small popula-
tion of duckweed (see "Floating Plants" in Appendix
1) can be netted when plants form windows against
the shoreline. Brush species, cattails, and other
shoreline vegetation can be cut with a sickle or pulled
by hand while still immature. Booms or barriers
extended across an incoming creek or stream can
often keep plants such as waterhyacinths (see
"Floating Plants" in Appendix 1) from entering the
pond. When confined, these plants can easily be hand
removed or sprayed with herbicide. While the simpl-
est mechanical harvesting devices for weed control
are often the cheapest, and often highly effective,
commercially made mechanical harvesters (Figure 8)
designed specifically for aquatic weed management
are available. These harvesters vary in size from
simple hydraulic sickle-bar cutters powered by a 5-
H.P. engine and mounted on the front of a pontoon
boat to 10,000-pound capacity harvesters which
convey cut vegetation on board for transport to
shoreline dumping sites. In general, large mechanical
harvesting equipment can be difficult to maneuver in
a smaller pond, and weed control cost would be
exorbitant for the private pond owner.

Biological Control
Ideally, the best weed control agent is one that
keeps weed pests restrained naturally. Many native
plants have biological restraints that keep them from
growing prolifically. The major aquatic weed problems
in Florida are caused by exotic plants that were
introduced from foreign lands without their natural
pests and controlling organisms. In the absence of
natural enemies, these exotic plants grow uncon-
trolled and rapidly invade new areas. To provide
some insight into biological control for these nuisance
plants, research scientists travel to their foreign

habitat searching for insects, disease, or other or-
ganisms that may aid in controlling their growth. In
theory, this concept sounds ideal; however, years of
research are required to insure that the introduced
organism does not become another dangerous pest.
Once it has been determined that the biocontrol
agent will not be a pest, and the control agent will
exist under the environmental conditions of the pest
host, the organism is released. Most biological or-
ganisms will not eradicate the host plant, but will
instead reduce the plant's potential to become a
serious pest.
Several biocontrol agents have been released in
Florida or occur naturally; however, others must be
added to the pond and are presently available for
release in Florida.
Insects and Plant Pathogens Over the years,
insects have proven to be the most popular biological
control agents due to their high degree of host
specificity. The insect is generally effective at destroy-
ing only the host plant because of their parallel
evolutionary development with the plant's taxonomic
characteristics. Plant pathogens such as viruses,
bacteria, fungi, or nematodes are already present in
the aquatic environment and may limit the growth of
aquatic weeds by invading weak or wounded plant
The alligatorweed flea beetle (Agasicles hygro-
phila), discovered in South America and introduced
into the United States in 1964, is the best example of
an extremely successful biocontrol program using
insects for aquatic weed control. In regions of the
country where the flea beetle can overwinter, as it
does in Florida, alligatorweed is no longer considered
a major weed problem.
The waterhyacinth has had several biocontrol
agents introduced to it over the years that help in
reducing the prolific growth that it is capable of;
however, unlike alligatorweed, these biocontrol agents

Fig. 8. Aquatic plant harvester clears weeds from a lake


don't appear capable of quickly controlling the plant.
Two waterhyacinth weevils (Neochetina eichhorniae
and N. bruchi), the waterhyacinth mite (Orthaga-
lumna terebrantis), and fungus (Cercospora rodmanii)
have been imported to Florida and can often be
found associated with the plant. Because one require-
ment of a successful biological control program
utilizing insects is self-dissemination, locating sources
of insects for introduction should not be necessary.
Herbivorous Fish Numerous exotic fishes
around the world are reported to consume aquatic
vegetation. However, because of the concern for
potential damage in Florida's diverse lakes and rivers,
only a few of these fish have been investigated and
even fewer show promise for weed control. Many of
these species may not be suitable for weed control
because the individual has insufficient consumption
(high stocking rates needed), they are prolific spawn-
ers (often cause overcrowding), or they are restricted
to warm climates (must be overwintered in controlled
environments ).
Of the fishes examined to date, the grass carp
(Figure 5) is the best candidate for aquatic plant
control in a variety of situations and climates and
may provide the only practical control method for
water bodies where herbicides cannot be used. This
fish has provided excellent control of submersed
plants, filamentous algae, and small floating plants
such as duckweeds. The grass carp is used by Arkan-
sas and other states for this purpose in natural lakes
and has been researched by a number of other states.
Florida has conducted research and has approved the
use of the triploid grass carp, which has three sets of
chromosomes compared to the normal two sets and
is thus sterile.
As stated previously, the grass carp does consume
vegetation and if stocked in sufficient numbers is
likely to remove all submersed plants from pond
systems. Before stocking ponds that have heavy
vegetation cover, it is often advantageous to first treat
with herbicides. In order to determine proper stock-
ing rates for a given pond, a competent fish biologist
should be consulted and a permit obtained from a
Florida Game and Fresh Water Fish Commission
There are three possible management strategies
utilizing grass carp: 1) complete vegetation removal
within one to two years with a heavy stocking rate;
2) winter stocking, before the spring growth of weeds
begins, using fewer fish to maintain a lesser amount
of vegetation in the system and increasing the grass
carp population as needed; and 3) integrated control
using herbicide treatments to obtain desired levels
quickly and stocking grass carp to maintain this level.
Again, the grass carp population should be adjusted

as needed. A word of caution is in order: it is much
easier to stock additional grass carp than to remove
unwanted fish from the system.
Controlling aquatic plants with herbicides is the
most commonly used method of weed control. Chemi-
cal weed control has several advantages.
Herbicides may be directly applied to undesir-
able vegetation, offering a high degree of
selectivity and leaving desirable levels of vegeta-
Pre-emergence application of appropriate
herbicides can provide early weed control. This
may be used to promote desirable vegetation
without competition during critical early growth
Herbicides reduce the need for mechanical
control which can increase turbidity and affect
fish populations.
Erosion may be reduced by promoting the
lower growing grass species for cover.
Many weeds, especially perennials, that cannot
be effectively controlled by other methods are
generally susceptible to herbicides.
Routine use of herbicides under a maintenance
program usually reduces the cost of weed
Herbicide Selectivity Herbicides may be placed
into two general categories: selective and nonselective.
Selective herbicides are used to control weeds without
damaging nearby plants, crops, lawns, and ornamen-
tals. Nonselective herbicides are chemicals that kill all
plants that are sprayed at an adequate rate. Herb-
icides in this latter category are used where no plant
growth is wanted such as fencerows, ditchbanks,
driveways, etc. Factors that influence selectivity
include application rate, time and method of applica-
tion, environmental conditions, stage of plant growth,
and the biological characteristics of the plant.
Mode of Action Herbicide activity can be
divided into contact and systemic types. Contact
herbicides only kill the parts of the plant that they
physically contact; therefore, the entire plant must be
sprayed. They usually cause rapid die-back of the
vegetation they come in contact with and are general-
ly more effective on annuals. Systemic herbicides are
absorbed by both roots and foliage and translocated
within the plant's vascular system. Systemics are
particularly effective against deep rooted perennial
weeds, providing long term control, and do not need
uniform coverage of the entire plant.


Herbicide Formulation The active ingredient of
a herbicide is rarely 100 percent of the formulation.
Instead, the herbicide is mixed with water or an oil
blend and often includes inert adjuvants that facili-
tate the spreading, sticking, wetting, and other modi-
fying characteristics of the spray solution. These
special ingredients usually improve the safe handling,
measuring, and application of the active ingredient.
The majority of liquid herbicide formulations are
emulsifiable concentrates (EC), or a mixture of
petroleum solvents and emulsifiers that allow the
formulation to mix with the water. Each gallon of
EC usually contains 2 to 8 pounds of active in-
gredient. The high concentration generally means
easier handling, transport, and storage. ECs require
little agitation and are considered to be nonabrasive.
ECs are usually mixed with water at a ratio of 1:50
or 1:100 prior to use.
Some of the herbicides marketed for aquatic plant
control are formulated into flowables (F). The active
ingredients in flowables are insoluble suspensions
mixed with a liquid simply to facilitate handling and
share many of the advantages of an EC.
Many of the aquatic herbicides have not only
liquid but dry formulations as well. The vast majority
of these dry formulations are sold as granules (G) or
pellets (P). The active ingredient is generally ab-
sorbed into clay particles with the amount of active
ingredient ranging from 1 to 15 percent. Granules are
convenient for spot treatments, are ready to use and
require no mixing, reduce drift hazards, and can be
applied easily. The disadvantages of granules are
their high expense per pound of active ingredient and
their ineffectiveness as a treatment on the foliage of
emergent plants.
Another common dry formulation is the wettable
powder (WP). WP formulations resemble a fine dust
and generally contain greater than 50 percent active
ingredient. When mixed with water, agitation is
required to keep the insoluble particles in suspension.
The advantages of a WP are the lower cost, ease of
handling, and ease of measuring. Some disadvantages
of WP are the abrasion of suspended particles on
spray equipment.and the requirement for constant
tank agitation.
Adjuvants An adjuvant is an inert ingredient
added to the spray solution in order to facilitate or
modify the action of the herbicide. Spray tank addi-
tives may include surfactants, thickening agents,
spreaders, stickers, wetting agents, penetrants, anti-
foaming agents or many other modifiers. Many
herbicides contain adjuvants in their formulation and
may not need any additional material added to the
spray tank; however, many of these same herbicide

labels may suggest that additional surfactant be
added. Most of the adjuvants are strictly optional and
may be added to help modify the spray solution. For
instance, a spreader-sticker may be added to the
herbicide mix for spraying a contact type of herbicide,
because covering as much of the leaf surface as
possible would increase the percentage of weed
control. Additional surfactant for wetting may be
necessary when target weeds have dense leaf hairs.
The best source of information for deciding on
adjuvant addition is the herbicide label or the chemi-
cal manufacturer's representative.
The Label All herbicide containers must have
attached to them a label that provides instructions for
storage and disposal, use of the product, and precau-
tions for the user and the environment. The label is
the law. It is unlawful to alter, detach, or destroy the
label. It is also unlawful to use a pesticide in a
manner that is inconsistent with or not specified on
the label. For example, herbicides that are sold for
use in the garden should never be used in ponds
unless the label specifies this use. Misuse of a herb-
icide is not only a violation of federal and state law;
herbicides used contrary to label directions may
seriously contaminate water, rendering it unfit for
fish, irrigation, and swimming, and as a source of
potable water. Herbicides sold for use in water have
been state and EPA approved and have undergone
years of costly and extensive research to insure their
environmental safety.
The herbicide label contains a great deal of infor-
mation about the product and should be read
thoroughly and carefully before each use. Before
purchasing a herbicide; read the label to determine:
whether the weed species can be controlled with
the product
whether the herbicide can be used safely under
particular application conditions
what herbicide formulation best suits your
needs and application equipment
how much herbicide is needed
where the herbicide can be used and what
restrictions apply if you are also watering
livestock, fishing, swimming, consuming as
potable water, watering crops, etc.
what the toxicity is to various fish species
when to apply the pesticide (time of year, stage
of plant growth, etc.)
whether there are any restrictions for use of
the pesticide (certified applications only, ditch-
banks only, ponds only, etc.)


what safety equipment is needed
signal word that indicates the acute toxicity to
humans, i.e., danger, warning or caution

Precautions with Herbicides When a large
percentage of a water body is infested with weeds,
care is needed when fish safety is a concern. Several
herbicides act on contact, killing the weeds in a
matter of hours. When aquatic plants die and begin
to decay, they remove oxygen from the water creating
what is known as a biological oxygen demand. If too
large an area in a pond volume is controlled, then
dissolved oxygen levels in the pond may drop below
the concentration necessary to sustain fish. Here are
several general rules to keep in mind when treating
aquatic plants.

1) Avoid treating on cloudy days when dissolved
oxygen levels will naturally be lower.
2) If a large portion of the pond is covered with
plants, treat no more than one-third to one-half
of the plants at once, leaving time between applica-
tions for oxygen recovery.
3) Treat early in the spring before plants get out
of control.
4) In order to get maximum performance from
your herbicide, treat when the water temperature
is above 60F and plants are actively growing.

The majority of EPA and state approved aquatic
herbicides have a wide range of safety with non-
target organisms. The level at which some herbicides
become toxic to fish is several hundred times higher

than field application rates. However, herbicides like
copper sulfate (CuSO4) may be toxic to several fish
species at label use rates and require extra precau-
tion when large treatments are to be made, especially
in soft water. Appendix 3 lists the 96-hour LC50
(lethal concentration to 50 percent of any particular
population) in ppm and also the pounds of various
aquatic herbicides needed per acre-foot of water to
be toxic to bluegill, channel catfish, rainbow trout,
crawfish, and freshwater shrimp.
When using herbicides, as with any toxic material,
it is important that personal exposure be kept to an
absolute minimum. Most accidents result from
careless handling and a general lack of label know-
ledge. Herbicides are categorized into four groups
based on their oral, dermal, and inhalation toxicity.
Every label contains a signal word (Danger, Warning,
or Caution) that indicates level of toxicity.
While mixing and spraying herbicides, protective
clothing and equipment should be used such as long-
sleeved shirts and long-legged pants, gloves, rubber
boots, and goggles or a face shield. Most labels will
suggest you wear protective clothing and will tell you
the precautions to be taken when using the herbicide.
While mixing, loading, handling, and cleaning up,
observe all safety recommendations on the label.
When minor spills occur, use absorbent materials
such as soil or sawdust to soak up the chemical.
Place contaminated materials into a sealed container
for disposal. Cleanup of a major spill may be too
difficult for an untrained person to handle. Should
there be a bad spill, call Chemtrec toll-free at 1-800-
424-9300 for emergency assistance. For first aid
information about herbicide poisoning, refer to the
label for instructions and contact your physician.


Figures 1 through 4 are reproduced with permission from the Soil Conservation Service:
Ponds -Planning, Design, Construction, USDA Agriculture Handbook 590, Washington,
D.C., 1982. Many of the photographs of aquatic plants were provided by the Florida
Department of Natural Resources.

How to Use the Appendices
Step 1: Use the information in Appendix 1 to identify your aquatic
plant problem. Biological and chemical controls for each
weed species are listed under the plant description.
Step 2: If you choose herbicides as a means of control, refer to
Appendix 2 and locate the herbicide listed as effective for
your particular weed problem. Product tradenames, water
systems labeled for use, mode of action, duration of herbi-
cidal activity, water use restrictions, and precautions are
listed for herbicides.
Step 3: Once you review the herbicides and decide which herbicide
best suits your problem, review Appendix 3 to insure that
there will be no toxicity problems.
Step 4: Appendix 4 will assist you in calculating the rate of herbi-
cide you need to apply.
Step 5: To check whether you will need a permit to use the herbicide
you select, call the Florida Department of Natural
Resources (904) 488-5631 for the biologist in your area.


Appendix 1.

Aquatic Weed Identification

Aquatic plants are commonly classified into several
categories depending on the location in the water
column they inhabit. Aquatic plants may be free
floating, emersed, submersed, or shoreline plants.
Free floating plants are rarely if ever rooted into the
soil and their leaves are located above the water.
Emersed aquatic plants are rooted in the soil under
water with their leaves on or above the water sur-
face. Submersed aquatic plants are usually rooted in
the soil with all or most of their leaves growing
under water. Ditchbank plants are not true aquatic
plants, but are often associated with the moist soils
located around ponds and lakes and are therefore
included here, as are common types of algaes.

Floating Plants
Common duckweed (Lemna minor)
Description: Small, footprint-shaped leaves, no more
than 1/8 inch long having one root. Leaves are pale
green and float flat on the water surface. Repro-
duction occurs by seeds and rapidly through
Control: Biological: grass carp. Herbicides: diquat,
simazine, fluridone.

Common salvinia (Salvinia minima)
Description: Circular leaves 1/4-1/2 inch in diameter
with dense leaf hairs on the upper leaf surface.
Leaves are brownish green and float flat on the
surface. Salvinia is a fern and reproduces by
spores and fragmentation.
Control: Biological: grass carp (partial). Herbicides:

Waterhyacinth (Eichhornia crassipes)
Description: Plants several inches to two feet in
height. Smooth leaves attached to spongy bulb-
shaped stalks. Reproduction is primarily through
the production of daughter plants.
Control: Biological: hyacinth weevil and fungus
(partial). Herbicides: 2,4-D, diquat, glyphosate.

Waterlettuce (Pistia stratiotes)
Description: Resembles a head of lettuce. Grows in a
rosette with spongy, dense hairy leaves 6-8 inches
in diameter. Daughter plants are the major means
of reproduction.

Control: Biological: waterlettuce weevil. Herbicides:
diquat, endothall liquid.

Emersed Plants
Pickerelweed (Pontederia lanceolata)
Description: An erect plant with lance-shaped leaves
up to 10 inches long. Each stem has violet-blue
flowers at the top. Reproduction occurs by .seed
and creeping rootstalks.
Control: Biological: partial control with grass carp.
Herbicides: 2,4-D, 2,4-D + dicamba, triclopyr.

Alligatorweed (Alternanthera philoxeroides)
Description: Hollow-stemmed perennial capable of
forming dense mats. Leaves are opposite between
2 and 4 inches long, and football-shaped. Stems
have a solitary white flower head at the tip.
Reproduction by fragmentation.
Control: Biological: alligatorweed flea beetles and
thrips. Herbicides: partial control with 2,4-D,
glyphosate, triclopyr.

Cattail (Typha species)
Description: Erect perennials (up to 9 feet) that can
reproduce by seed or creeping rootstalk. Grass-like
leaves are flat and smooth to the touch. Flowers
look like a "cat's tail" and can be found in a tightly
packed spike usually 6-8 inches long.
Control: Herbicides: diquat, glyphosate, fluridone.

Pennywort (Hydrocotyle umbellata)
Description: Dark green, shiny rounded leaves which
are centrally attached to a long stalk. Leaves may
lie flat on the water surface or erect. Pennywort
reproduces by seed and creeping stems.
Control: Herbicides: diquat, 2,4-D, glyphosate.

Smartweed (Polygonum species)
Description: Leaves are alternate, lance-shaped, and
attached to swollen joints on the stem. The flower
stalk consists of many small pinkish white flowers
in a single spike. Smartweed spreads by seed, and
may form large floating mats.
Control: Herbicides: partial control (species depen-
dent) with glyphosate, 2,4-D, triclopyr.

White water-lily (Nymphaea odorata)
Description: Leaves are flat, rounded, and attached at
the center to the stalk. Leaves are often 10 inches
in diameter and split to the center on one side.



Brazilian Pepper Salvinia Fanwort

Water Primrose



Wax Myrtle

Macrophytic Algae


.7 rl."

Willow Cattail







" *

White Waterlily


Maidencane Sedge










Planktonic Algae Southern Naiad

Filamentous Algae



The flower is sweet-scented, white and showy.
Reproduction is by seed and branching stems.
Control: Herbicides: fluridone, 2,4-D liquid and
granular, glyphosate.

Spatterdock (Nuphar luteum)
Description: Large heart-shaped leaves arising from
a stalk attached to a thick creeping root system.
The flower is yellow and about one inch in diame-
ter. Reproduction is by seed and new sprouts.
Control: Herbicides: glyphosate, fluridone.

Submersed Plants
Coontail (Ceratophyllum demersum)
Description: Leaves grow in a whorl, are finely
dissected, and have teeth on one side of the leaf
margin. Leaves are 1/2-1 inch in length and
crowded towards the stem tip giving the ap-
pearance of a raccoon's tail. Coontail is rootless
and floats near the surface in the warmer months.
Reproduction is by seed and fragmentation.
Control: Biological: grass carp. Herbicides: dichlobenil,
diquat, endothall liquid and granular, simazine,
fluridone, 2,4-D granular.

Hydrilla (Hydrilla verticillata)
Description: Long stemmed, branching plant that is
rooted to the bottom and often forms large surface
mats. Leaves grow in a whorl with toothed mar-
gins that feel rough. Hydrilla can spread by plant
fragments, underground stems, seed, leaf buds, or
buds located on the underground stems.
Control: Biological: grass carp. Herbicides: copper,
diquat, endothall liquid and granular, fluridone.

Bladderwort (Utricularia species)
Description: A submersed, free floating plant, having
a variety of growth forms. Although leaf shapes
and flowers differ, all species bear small unlike
bladders which are used to trap small aquatic
animals. Reproduction is by seed and fragmenta-
Control: Biological: grass carp. Herbicides: diquat, 2,4-
D granular, fluridone.

Southern naiad (Nqjas guadalupensis)
Description: Bottom rooted, slender leaved plant with
branching stems and a dark green to greenish
purple color. Leaves are less than 1 inch in length
and narrow. Reproduction is by seed and fragmen-

Control: Biological: grass carp. Herbicides: dichlobenil,
diquat, endothall liquid and granular, simazine,
fluridone, 2,4-D granular.
Fanwort (Cabomba caroliniana)
Description: Leaves of fanwort are finely dissected
and fan-shaped. Leaves are opposite and generally
no more than 1-11/2 inches wide. The flower is
white or cream colored, about one-half inch in
diameter and blooms above the water surface.
Reproduction is by seed and fragmentation.
Control: Biological: grass carp. Herbicides: diquat,
fluridone, 2,4-D granular.

Pondweed (Potamogeton species)
Description: Several species of pondweed are found in
Florida; Illinois pondweed (P. illinoensis) is most
frequently encountered. It has both floating and
submersed leaf forms. The football-shaped floating
leaves are not always present, but are easily
distinguishable from the lance-shaped submersed
leaves. The flowers are clustered together on a
spike 1-2 inches long located just above the water
surface at the stem tip. Reproduction is by seed
and from underground stems.
Control: Biological: grass carp. Herbicides: copper
sulfate, dichlobenil, diquat, endothall liquid and
granular, simazine, fluridone, 2,4-D granular.

Grasses and Sedges
Torpedograss (Panicum repens)
Description: Narrow leaved (less than --inch wide),
with stems often several feet in length. Tor-
pedograss creeps horizontally by underground
stems and forms large floating mats. Reproduction
is by seed and creeping stems.
Control: Biological: partial control with grass carp.
Herbicides: glyphosate, fluridone.

Maidencane (Panicum hemitomon)
Description: Maidencane leaves usually grow at 900
angles from the stem and generally -inch in
width. An extensive creeping root system allows
maidencane to form dense floating mats with
stems often several feet in length. Reproduction is
by seed and creeping root stalk.
Control: Biological: partial control with grass carp.
Herbicides: glyphosate.

Paragrass (Brachiaria purpurascens)
Description: Paragrass often forms stems several
yards in length which often fall on the ground.


Paragrass can be easily identified by the dense
hairs located at the stem joints. Dense floating
mats often form. Reproduction is by seed and stem
joints forming roots.
Control: Biological: partial control with grass carp.
Herbicides: glyphosate, fluridone, hexazinone.

Sedge (Cyperus species)
Description: Many sedges are found in Florida and
are generally difficult to identify by species. In
general, sedges can be identified by the triangular
stem and leaf blades, which are generally rough to
the touch. Flower stalks arise from the center
forming a compact group or headlike cluster of
flower spikes. Reproduction is by seed.

Control: Herbicides: partial control with glyphosate.

Ditchbank Brush
Wax Myrtle (Myrica cerifera)
Description: Shrub or small tree usually 10 feet tall.
Leaves are alternate, pale green, and lance-shaped.
When crushed, leaves emit a pleasant aroma. Close
inspection of the leaves will reveal numerous small
dark scales on top and bright orange scales below.
Reproduction is by seed.
Control: Herbicides: hexazinone, tebuthiuron, tri-

Willow (Salix species)
Description: Fast growing shrub which can become a
tree in a short period of time. Leaves are alternate
and lance-shaped with finely toothed margins. The
fruit capsule contains many small hairy seeds
which drift in air currents.
Control: Herbicides: partial control with 2,4-D, gly-
phosate, 2,4-D + dicamba, hexazinone, tebuth-
iuron, imazapyr.

Brazilian pepper (Schinus terebinthifolius)
Description: An extremely fast growing shrub found
predominantly in disturbed areas of south Florida.
This aggressive exotic produces large quantities of
seeds contained in a red fruit usually about -inch
in diameter. Reproduction is by seeds.
Control: Herbicides: glyphosate, 2,4-D, 2,4-DP, 2,4-D
+ dicamba, tebuthiuron, imazapyr, triclopyr.

Water primrose (Ludwigia species)
Description: Small shrub attaining height of up to 6
feet with multiple branching stems. Leaves are
lance-shaped with small soft hairs on both sides.
Flowers are yellow with four symmetrical petals.
Reproduction is by seed and underground stems.
Control: Herbicides: glyphosate, fluridone, 2,4-D
granular, imazapyr.

Macrophytic algae
Description: Macro, meaning large, describes a type
of algae that looks more like a submersed plant.
Capable of attaining several feet in length, musk-
grass (Chara species), is the most common of these
algae found in Florida. The algae appear to have
a whorl of spined leaves, grey-green in color,
resembling the submersed plant, coontail. How-
ever, algae have no true leaves. When crushed,
Chara emits a musky odor.
Control: Biological: grass carp. Herbicides: copper,
endothall liquid and granular, simazine.

Filamentous algae
Description: Many species of filamentous algae are
frequently a problem in Florida ponds. These
threadlike filaments are often called "pond scum"
or "pond moss" when they are seen floating on the
pond surface. Although many species of filamen-
tous algae can frequently become a problem to
pond owners, most species can be controlled in a
similar manner. A few species, especially some of
the blue-green algae (i.e. Pithophora and Lyngbya),
are difficult to control and would require special
recommendations from a qualified biologist
Control: Biological: partial control with grass carp.
Herbicides: copper, diquat, endothall (Hydrothol),
Planktonic algae
Description: Microscopic planktonicc) algae are small
plants that cannot be identified without magnifica-
tion. They occur in all ponds and, after fertiliza-
tion, give the pond its green color. Most of the
microscopic algae are beneficial to ponds, convert-
ing nutrients into a source of food in the food
chain. There is rarely a need to control micro-
scopic algae; however, when large blooms occur,
oxygen depletion, foul odors, off-flavor fish, and
even fish kills may occur.
Control: Herbicides: copper, simazine.


Appendix 2.


Copper Products
Copper sulfate cupricc sulfate pentahydrate)
Tradenames: Kocide, Tennessee Chemical Copper
Sulfate (snow and granular), Algimycin PLL-C, SA
50 Granular.

Copper chelate (alkanolamine complex)
Tradenames: CUTRINE-PLUS (liquid and granular),

Copper chelate (triethanolamine complex)
Tradenames: K-TEA, AQUA-PURE, AV-70 Plus.

Copper chelate (ethylenediamine complex)
Tradenames: Komeen, Koplex.
Water systems labeled for use: Copper sulfate: im-
pounded waters, lakes, ponds, reservoirs, and
irrigation systems. Copper chelates: ornamental,
fish, and fire ponds; potable water reservoirs;
freshwater lakes and fish hatcheries.
Mode of action: Contact herbicide, often used in
combination with other contact herbicides.
Duration of herbicidal activity: Copper sulfate may
persist up to 7 days before the free copper is
precipitated to insoluble forms and remains an
inactive precipitate in bottom sediments. As the
hardness of the water increases, the persistence of
the free copper decreases. The chelated coppers
can be used where hard water may precipitate
uncomplexed forms of copper too rapidly.
Water use restrictions: Waters treated with copper
sulfate or one of the various copper chelates may
be used for swimming, livestock watering, irriga-
tion, and fishing immediately after chemical
application. If treated water is to be used as a
source of potable water, the metallic copper residue
must not exceed 1 ppm.
Precautions: Copper sulfate can be very corrosive to
steel and galvanized pipe. Chelated coppers are
virtually noncorrosive. Contact with skin and eyes
may be irritating. As water hardness decreases,
toxicity to fish increases. Copper. sulfate may be
toxic to fish species at recommended dosages.
Generally, the chelated coppers are nontoxic to
trout, tropical fish, ornamental fish, and other
sensitive fish at recommended dosages.

2,4-D Products
2,4-D Granular
Tradenames:Aqua-Kleen, AQUACIDE, WEEDTRINE-

2,4-D Ester
Tradenames: VISKO-RHAP LV Ester 2D, WEED

2,4-D oil soluble amine

2,4-D Amine
Tradenames: SMCP Standard 2,4-D Amine, 2,4-D
Amine No. 4, Asgrow 2,4-D Amine, WEEDAR 64,

2,4-D + dicamba
Tradenames: BANVEL-720.
Water systems labeled for use: In general, lakes and
ponds. Other systems are also specified on specific
product label. BANVEL-720 is labeled only for
Mode of action: 2,4-D is a systemic herbicide widely
used for control of most broadleaf weeds. Ester
formulations will control more plant species than
amine formulations, but due to the high volatility
of ester formulations, vapors may damage off-
treated areas. Salt and amine formulations of 2,4-
D are most often used in aquatic plant control.
Duration of herbicidal activity: 2,4-D breakdown in
warm, oxygenated waters is rapid and the herbi-
cide is usually inactivated in 1-4 weeks depending
on the rate and formulation used.
Water use restrictions: Restrictions vary among labels.

Precautions: Avoid drift. A rain-free period of at least
6 hours is required in order to insure a lethal dose
has been absorbed by treated foliage. Ester for-
mulations are volatile and may drift off site in a
vapor phase. Never treat more than one-half of
the lake at one time as decaying vegetation will
consume dissolved oxygen, thus suffocating fish.

Tradenames: Granular: CASORON G-10, NORO-SAC
Water systems labeled for use: Ponds, reservoirs and
lakes. Not for use in flowing water.


Mode of action: Systemic herbicide primarily absorbed
by roots and translocated to foliage.
Duration of herbicidal activity: Herbicide may remain
effective for a period of 2-6 months and longer
under favorable conditions.
Water use restrictions: Do not apply to water used for
irrigation, livestock watering, or human consump-
tion. Do not use in commercial fish or shellfish
water. Do not use fish for a 90-day period after
Precautions: Length of activity and breakdown are
dependent on soil type. Apply only to areas where
complete plant control is desired.

NORKEM 500, Diquat Herbicide-H/A,
Water systems labeled for use: May be used in slowly
moving bodies of water, ponds, lakes, rivers,
drainage and flood control canals, ditches, and
Mode of action: Contact herbicide.
Duration of herbicidal activity: Diquat is rapidly and
completely inactivated by soil.
Water use restrictions: Do not use treated water for
animal consumption, spraying, irrigation, or drink-
ing within 14 days after treatment. Do not swim
in treated water for 24 hours after treatment.
Precautions: Do not apply to muddy water because
the diquat will be inactivated. Never treat more
than 1/3-1/2 of a densely vegetated pond at any one
time because rapidly decaying vegetation will
deplete oxygen, thereby suffocating fish. Skin
contact may cause irritation. Avoid drift.

Tradenames: Direx 4L, DIURON 80, KARMEX.
Water systems labeled for use: Irrigation and drainage
ditches that have been drained of water for a
period of 72 hours. After 72 hours diuron is fixed
to the soil and the ditch may then be used.
Mode of action: Diuron is readily absorbed through
the root system, less so through foliage, and
translocated upward toward plant foliage.

Duration of herbicidal activity: Control duration will
vary with amount of chemical applied, soil type,
rainfall and other conditions. Usually control will
last for a period of 10-12 months.
Water use restrictions: Do not use directly in water.
Apply before expected seasonal rainfall to a drain-
ed moist soil. Allow to stand for 72 hours before
Precautions: May irritate eyes, nose, throat, and skin.
Avoid breathing dust. Apply before expected
seasonal rainfall. Do not treat any ditch with
desirable tree roots extended into them or injury
may result. Prevent drift of dry powder to desir-
able plants. Do not contaminate any body of water.

Tradenames: Granular: AQUATHOL, HYDROTHOL
191. Liquid: AQUATHOL K, HYDROTHOL 191.
Water systems labeled for use: Irrigation and drainage
canals, ponds and lakes.
Mode of action: Contact herbicide.
Duration of herbicidal activity: Microbiological break-
down is fairly rapid in water and soil with a short
herbicidal duration.
Water use restrictions: Do not use fish for food within
3 days of treatment. Restrictions on watering
livestock, irrigation, and domestic purposes range
from 7-25 days depending on the concentration of
herbicide used.
Precautions: Hydrothol 191 liquid + granular should
not be used where fish are an important resource.
Fish may be killed by dosages necessary to kill
weeds. Skin contact may cause irritation. May be
corrosive to application equipment.


Tradenames: Sonar 4AS, Sonar 5P, Sonar SRP.
Water systems labeled for use: Lakes, ponds, ditches,
canals, and reservoirs.
Mode of action: Fluridone is foliage absorbed and
translocated into the actively growing shoots where
destruction of the chlorophyll pigments occurs,
resulting in white growing points.


Duration of herbicidal activity: Depending upon
application and vegetation being controlled, control
may last 1 year.
Water use restrictions: Do not apply within 1320 feet
of any potable water intake.
Precautions: Do not use treated water for irrigation
of agronomic crops or turf for 7 to 30 days follow-
ing treatment. Trees or shrubs growing in treated
water may be injured. Higher treatment rates will
be required if there is a large turnover in water
volume in treated water.

Water systems labeled for use: Lakes, ponds, streams,
rivers, ditches, canals, reservoirs, and any other
freshwater bodies.
Mode of action: Glyphosate is foliage absorbed and
translocated throughout the plant and root system,
killing the entire plant.
Duration of herbicidal activity: Only effective at the
time of treatment.
Water use restrictions: There is no restriction on
water use after application. Do not apply within \-
mile upstream of potable water intakes.
Precautions: Not to be used for submersed or pre-
emergence vegetation. Floating mats of vegetation
will require treatment. A rain-free period of 6
hours after application is required. May be cor-
rosive to galvanized steel. Avoid drift to desirable
vegetation as glyphosate is nonselective and will
affect contacted vegetation.

Tradename: VELPAR L.
Water systems labeled for use: Drainage ditchbanks
and other similar areas.
Mode of action: Absorbed through foliage and roots
giving some contact activity while the remaining
herbicide is translocated into foliage.
Duration of herbicidal activity: 3-6 months depending
on rate applied, rainfall and soil texture.
Water use restrictions: Not labeled for use in water.
Only for general weed and brush control along
drainage ditchbanks and similar areas.
Precautions: Injury to desirable trees may occur from

failure to observe recommended rates. Do not
contaminate any water supply.

Tradename: ARSENAL.
Water systems labeled for use: Non-irrigation ditch-
banks and other similar areas.
Mode of action: Both foliage and root absorbed and
translocated throughout the entire plant.
Duration of herbicidal activity: Provides control of
existing and germinating seedlings throughout the
growing season.
Water use restrictions: Not labeled for use in water.
Only for non-irrigation ditchbanks and other
similar areas.
Precautions: Do not contaminate any water supply.
Do not apply on ditches used for irrigation. Do not
treat in areas where desirable tree roots are
visible. Prevent drift to desirable plants. Should
not be mixed or stored in unlined steel containers
or spray tanks.

Tradename: Aquazine
Water systems labeled for use: Ponds.
Mode of action: Root absorbed and translocated to
actively growing portions of the plant.
Duration of herbicidal activity: Control will generally
last throughout the growing season.
Water use restrictions: Treated ponds may be used
for fishing and swimming immediately after spray-
ing. Water from treated ponds may not be used for
irrigation, watering livestock, or human consump-
tion for 12 months following treatment.
Precautions: Injury may occur to bordering trees with
roots visibly extended into the water. Cannot be
used to spot treat plants. Only for use in ponds
which have little or no outflow. Do not treat ponds
with excessive infestations of plants because
decomposition may suffocate fish. Some algae
species may require several treatments.

Tradename: SPIKE.
Water systems labeled for use: Ditchbank.
Mode of action: Primarily root absorbed with some


foliar absorption. Tebuthiuron is translocated
through the entire plant.
Duration of herbicidal activity: Weed suppression may
last for several years.
Water use restrictions: Not for use in water. Do not
contaminate any body of water.
Precautions: Do not apply to ditches used to trans-
port irrigation or potable water. Roots which
extend into the treated area will absorb the
herbicide; do not treat near desirable trees or
shrubs. Do not broadcast treat an area where
grass cover is desired.

Tradenames: Garlon 3A, Garlon 4.
Water systems labeled for use: Non-irrigation ditch-
Mode of action: Triclopyr induces characteristic auxin-
type responses in growing plants. It is absorbed by

both leaves and roots, and it is readily translocated
throughout the plant. Foliage applications have
achieved maximum plant response to treatment when
the treatment has been applied soon after full leaf
development and soil moisture is adequate for normal
plant growth.
Duration of herbicidal activity: Time required for 50
percent breakdown in soil is between 10 and 46
days depending on environmental conditions and
soil type. At label rates, phytotoxic residues in soils
should cause no problems. Triclopyr has a 2- to 6-
hour half-life in Water.
Water use restrictions: Not labeled for use in water
(EUP only).
Precautions: Keep out of lakes, streams or ponds. Do
not contaminate water by cleaning of equipment or
disposal of.wastes.

Appendix 3. Agriculture Chemical Toxicity to Selected Aquatic Animals
Toxicity of Various Herbicides to Species Shown. The 96-hour LCo is given in the ppm columns. The pounds of material
needed per acre-foot of water (325,850 gallons) for the 96-hour LCso is given in the lb columns.*

Herbicide Bluegill Channel Catfish Rainbow Trout Crawfish Freshwater Shrimp
Common Name ppm lb ppm lb ppm lb ppm lb ppm lb
Endothall (AQUATHOL K) 343 932.9 150 408.0 230 625.0
Triclopyr (Garlon 3A) 891 2423.0 552 1501.4
Simazine (AQUAZINE) 16.0 43.5 2.8 7.6
Dicamba (BANVEL) 50.0 136.0 28 76.1 56 152.3
Copper sulfate Toxicity depends on total alkalinity of water. Can be very toxic in water with low alkalinity.
Dichlobenil (CASORON) 8.3 22.5 6.3 17.1
Copper ammonium carbonate 3.28 8.9 0.02 0.05
Diquat (Ortho) 245 666.4 10 27.2
Endothall (HYDROTHOL
191) 0.94 2.5 0.5 1.3 0.5 1.5 0.05 0.1
Diuron (KARMEX) 8.2 22.3 4.9 13.3
Lime sulfur 49.0 133.3 8.0 21.7
Rotenone 0.02 0.06 0.002 0.007 0.03 0.08
Glyphosate (ROUNDUP) 5.6 15.2 13.0 35.3 8.3 22.5
Tebuthiuron (SPIKE) 112 304.6 144 391.6
Tribasic copper sulfate Toxicity depends on total alkalinity of water. Can be very toxic in water with low alkalinity.
Hexazinone (VELPAR) 370 1006.4 320 870.4 56.0 152.3
2,4-D (WEEDAR 64) 0.6 1.60 0.3 0.8 0.2 0.6 13.89 3778.1 0.1 0.4
2,4-D (WEEDONE 170) 10.4 28.2 19.4 52.7 0.6 1.7 2.7 7.3

*Adapted from: Publication 1455, Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture,
by Dr. Thomas L. Wellborn, Jr., Leader, Extension Wildlife and Fisheries, Ruth Morgan, Associate Coordinator and Specialist Pesticide
Impact Assessment, and Geoffrey W. Guyton, Computer Programmer, Extension Entomology.
All ppm values are given in active ingredient. When using a combination of chemicals, check each chemical in the combination to
determine the toxicity of the combination. Always use pesticides according to the label directions which are on the products) purchased.
Tradenames are used only for the purpose of information, and the Mississippi Cooperative Extension Service does not guarantee
or warrant the standard of the product, nor does it imply approval of the product to the exclusion of others that also may be suitable.
The Federal Environmental Pesticide Control Act of 1972 stipulates: "The use of any registered pesticide in a manner inconsistent
with labeling instructions is prohibited. Under current law, penalties may be levied against a purchaser who misuses pesticides." Pesticide
salesmen, dealers, commercial applicators and university personnel also have a responsibility to use or recommend only EPA registered
pesticides according to the label.


Appendix 4. Conversion Factors and Formulas for Herbicide Calculations

Formulas for Active Ingredient
(1) Gallons of liquid formulation required = lb ai*required + lb ai per gal of concentrate
(2) Pounds of dry formulation required = lb ai required + % ai in formulation expressed as decimal

Formulas for Herbicide Application to Ponds or Lakes
(3) Volume of pond in cu ft = surface area in sq ft x average depth in ft
(4) Volume of pond in ac ft = surface area in ac x average depth in ft
(5) Volume of pond in ac ft = volume of pond in cu ft + 43,560 ft2 per acre
(6) Total gal of chem required = ac ft x ppmv x 0.33
(7) ppmw = lb ai of chem applied + volume in ac ft x 2.72
(8) Total lb ai required = ac ft x 2.72 x ppmw desired
(9) Total gal of liquid formulation required = ac ft x 2.72 x ppmw desired lb ai per gal of concentrate

Acre-feet Calculation
(10) Acre-feet = acres x average depth in feet

Acreage Calculations
(1la) Rectangular shape
Acres = width in ft x length in ft + 43,560 ft2 per ac
(lib) Circular shape
Acres = 3.14 x (radius in ft)2 + 43,560 ft2 per ac

Herbicide Application Coverage
(12) Acres/min = swath width in ft x speed in mph + 495

Volume of Herbicide Concentrate Required
(13) Gallons of Herbicide Concentrate Required = weight of active ingredient required in spray mixture -
weight of active ingredient per gallon of herbicide

Abbreviations: ai = active ingredient ac = acre
ppmw = parts per million by weight ppmv = parts per million by volume



Multiply By To get



Cubic feet
Cubic feet
Cubic feet
Cubic feet
Cubic feet
Cubic feet
Cubic feet
Cubic feet
Cubic feet
Cubic feet
Cubic feet
Cubic feet

Cubic yards
Cubic yards
Cubic yards
Cubic yards
Cubic yards
Cubic yards
Cubic yards
Cubic yards










Feet per minute
Feet per minute
Feet per minute
Feet per minute
Feet per minute
Feet per minute


Square meters
Square yards
Square feet

Cubic meters
Cubic feet

Cubic meters
Cubic yards
Quarts (dry)
Quarts (liquid)
Pints (dry)
Pints (liquid)
Pounds of water
Cubic inches
Cubic centimeters

Cubic meters
Cubic feet
Gallons (liquid)
Quarts (liquid)
Pints (liquid)
Cubic inches

Quarts (liquid)
Pints (liquid)
Ounces (liquid)


Miles per hour
Feet per second
Kilometers per hour
Meters per minute
Yards per minute
Feet per hour

Cubic meters
Cubic feet
Quarts (liquid)
Pints (liquid)
Ounces (liquid)
Cubic inches (liquid)
Cubic inches (dry)
Cubic centimeters


Multiply By To get

Gallons of water
Gallons of water
Gallons of water
Gallons of water
Gallons of water
Gallons of water




Cubic meters
Cubic yards
Cubic feet
Pounds of water





Grams per liter
Grams per liter
















Miles per hour
Miles per hour
Miles per hour
Miles per hour
Miles per hour


Parts per million

Square meters
Square yards
Square feet




Cubic meters
Cubic feet
Gallons (liquid)
Kilograms of water
Quarts (liquid)
Pints (liquid)
Cubic inches
Cubic centimeters
Grams of water



Feet per second
Kilometers per hour
Meters per minute
Yards per minute
Feet per minute


Multiply By To get

Ounces (liquid)
Ounces (liquid)
Ounces (liquid)
Ounces (dry)
Ounces (liquid)
Ounces (liquid)

Ounces (liquid)
Ounces (liquid)
Ounces (dry)
Ounces (liquid)
Ounces (dry)

Parts per million (ppm)
Parts per million
Parts per million
Parts per million
Parts per million

Parts per million
Parts per million

Parts per million
Parts per million

Parts per million

Parts per million

Parts per million










Quarts (liquid)
Pints (liquid)
Cups (liquid)
Cubic inches


lites per cubic meter
Grams per liter
Milliliters per liter
Ounces per 100
gallons of water
Grains per US gallon
Gallons per acre-
foot of water
Milligrams per liter
Milligrams per
Milliliters per cubic
Pounds per acre-
foot of water
Pounds per million
gallons of water




Pounds of water
Pounds of water
Pounds of water
Pounds of water

Square miles
Square miles
Square miles
Square miles
Square miles
Square miles




Cubic feet
Cubic inches

Square kilometers
Square meters
Square yards
Square feet

Metric ton


Reprinted October 1990.

Printing of this publication was funded in part through a cooperative agreement between the IFAS Center
for Aquatic Plants and the Florida Department of Natural Resources, Bureau of Aquatic Plant Management.

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