In Florida, the use of aquatic herbicides is the primary method for managing invasive aquatic and wetland plants such as hydrilla, water hyacinth, water lettuce, torpedo grass, and other wide-spread and highly invasive aquatic weeds. Take a look at some infestations.

THE COST
Approximately $60 million annually (2008) is spent managing plant invaders in Florida's lakes, rivers, canals, marshes and swamps. (This includes expenditures by state agencies, water management districts, counties and cities; this does not include private company and individual efforts such as plant management in retention and condo ponds or in agricultural canals, nor does it include costs of upland invasive plant management.)

INTUITIVELY, MOST PEOPLE WOULD PREFER TO USE MEANS OTHER THAN HERBICIDES to fight invading plants, means such as machines to collect the plants, or fish and insects to eat the plants. Our intuition is bolstered by the fact that well-meant, but ultimately unwise, use of certain chemicals in decades past resulted in environmental problems such as bioaccumulation of compounds in birds and other animals, and direct killing of fish, cattle and other animals.

Environment managers today, including aquatic weed managers, have learned from the past, and are determined to conduct their necessary work in well-considered ways using compounds that are registered for use and regulated by the U.S. EPA as well as by state agriculture and environment authorities.

Continuing research by chemists, agronomists and other scientists, as well as education and training of personnel, make invasive plant management using herbicides increasingly more of a science than an art. However, today's environment agency employees as well as citizens are, and ought to be, vigilant against pesticide mis-use; whether herbicide, insecticide or any-cide; whether by agencies, companies or individuals.

So please read on, and learn more about the use of aquatic herbicides in the fight against invasive plants.

CONSIDERING ALL, today's invasive plant managers, more often than not, must rely on herbicides to turn back rapidly invading plants. When circumstances make herbicidal control the method of choice, invasive plant managers take special care to:

a) use only herbicides approved by the U.S. Environmental Protection Agency;
b) apply the herbicides at the proper, legal rates, according to the plant, location, etc.;
c) apply the herbicides selectively to the target plant(s); and
d) apply the herbicides as carefully as possible.

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MANAGEMENT AGENCIES
More than 100 government agencies and even more companies in Florida employ workers to detect and remove unwanted plants that are invading our wetlands, lakes and rivers. Federal, state and local governments have been involved in plant management in Florida for more than 110 years. Here is a map and list of agencies in Florida that conduct aquatic plant management.

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MAINTENANCE CONTROL
Because it is impossible to eliminate every single invader plant, "maintenance control" has become the mantra of today's invasive plant manager. Simply stated, maintenance control means keeping the invading plants down to the lowest levels possible. In fact, maintenance control is part of Florida law. Reduced aquatic weeds and reduced herbicide use prove this guiding principle. More about maintenance control...

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HERBICIDE HISTORY
Since the late 1800s, various chemicals have been applied to our freshwaters to help stem the tide of invading aquatic and wetland plants. Of course, we wouldn't use some of them today for plant management, any more than we'd use leaches to treat headaches. This brief history of aquatic herbicide development tells the tale, from sea-salt and sulfuric acid used in the early years; to 2,4-D beginning in the 1940s; to endothall, fluridone and other newer compounds that were discovered and developed and are in use today.

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FLORIDA'S AQUATIC HERBICIDES
In 2009, there are eleven herbicides registered for use in Florida waters for plant management. That is, there are eight herbicidal active ingredients registered for use by the U.S. EPA and the Florida Department of Agriculture and Consumer Services. These active ingredients include: 1) chelated copper; 2) diquat; 3) endothall; 4) fluridone; 5) glyphosate; 6) 2,4-D; 7) triclopyr; 8) imazapyr; 9)carfentrazone; 10) imazamox; 11) and penoxsulam. Here are their descriptions.

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CHOOSING HERBICIDES
Public and private plant managers in Florida choose their aquatic herbicide for each job according to target plant, water body type, uses of the water body, wind, temperature, water depth, and other factors such as efficiency and cost-effectiveness. Here are things managers take into account when choosing which aquatic herbicide(s) to use for each plant species in each aquatic or wetland site.

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SELECTIVELY APPLYING HERBICIDES
According to field conditions, aquatic herbicide applicators choose formulations, adjuvants and strategies to apply herbicides "selectively", to the target plants. The plant manager's goal is to conserve or enhance the non-target native plants and animals of our watery environments by removing competetion and other harmful impacts from invasive species. Depending on the herbicide used, the plant location and other variables, environment managers use a variety of devices to apply herbicides. Here are things plant managers consider in order to selectively apply aquatic herbicides to control plants.

Read the Aquatics article "HOW TO BUILD WEIGHTED TRAILING HOSES" by Dr. William Haller, et al

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HERBICIDE ADJUVANTS
Aquatic herbicide technicians also may use other man-made and natural chemicals called "adjuvants" to give certain properties to their herbicide spray mix. These additives may cause the herbicide to spray with less drift, stick to the leaves better, they may cause the herbicide to spread more evenly, and so on. They are meant to make herbicides more effective. Here is information about aquatic herbicide additives.

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ENVIRONMENTAL CONSIDERATIONS
Environmental conditions at the time of application are very important considerations for the successful use of aquatic herbicides. The effects of wind, rainfall, temperature, stratification, water quality and other conditions are taken into account by the invasive plant manager. Following the label and using common sense means more invasive plants for the dollar will be controlled. Environmental conditions are discussed here.

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HERBICIDE IMPACTS
Using aquatic herbicides has the potential to cause certain impacts on the environment, from the death of large amounts of plants (expected), to water-oxygen depletion caused by bacteria as they "consume" the dead plants (unseen but expected), and resulting fish-suffocations (not wanted). Here are certain things that eco-managers do to reduce the impacts of herbicide applications on the environment.

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WATER USE RESTRICTIONS
Some herbicides disappear from the watery environment very quickly after application; others take longer. Whenever agencies and companies apply aquatic herbicides, as a safety precaution, they place notices and posters in the area to inform the public of "water-use restrictions" that may be in effect after application; these vary from no use restrictions at all to restrictions lasting one month's time. Here is a chart showing water-use restrictions to be in effect after aquatic herbicides have been used in swimming or fishing areas or in drinking-water-intake areas.

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HERBICIDE TESTING & TOXICITY
Testing and EPA-registration are costly and time-consuming requirements for chemical companies. Herbicides and other pesticides are subjected to batteries of laboratory and field tests in order to better understand the pesticides' "mode of action", persistence, breakdown products, toxicity to non-target organisms and other characteristics in order to protect the environment and the public-at-large. Here are the EPA tests and milestones aquatic herbicides must meet, and a chart of their toxicities.

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HERBICIDE LABELS
Caution. Warning. Danger. Do you know the difference? Every pesticide used in the home or in the environment must display one of these cautionary statements of relative hazardousness. For your information, pesticide "labels are also the law". Whether you are an individual applying cans of insecticide in your home or work for an environment agency applying gallons of herbicide to a river, the product's label has passed muster with the EPA. Because EPA-approved labels are considered to be legally binding on pesticide users, all instructions on the label must be followed, or severe and costly penalties can result. Have a look at information about aquatic herbicide labels.

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FWC REGULATIONS & PERMITS
Depending on who you are and what your intentions are, obtaining government permits may or may not be in your future. Before applying herbicides to kill invasive plants on your lake or river shore, err on the side of right and contact your area's F.W.C. regional biologist. The biologist will identify the plants for you and make management recommendations (at no charge). According to the situation, the regional biologist may also inform you that you need a permit (also at no charge). Here is what a permit is, who is required to have one, and where to get one.

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EXTENSION SERVICE ASSISTANCE
The University of Florida, and all land-grant universities in the U.S., maintain the "Extension Service". Extension offices are in all U.S. counties. At no charge, your local Extension agent will look at your aquatic plant problem, will report what he's seen to, and ask for the latest management recommendations from, the state's Extension Specialist for invasive plants. The Extension agent will later get back to you and pass along the Specialist's recommendations. Here are links to all 67 County Extension offices in Florida.

PREVENTION

Preventing the introduction and spread of non-native plants in Florida's waterways is the most effective and least expensive means of conserving Florida's natural freshwater habitats.

Like all plant management techniques, herbicidal controls are costly tools to use in the fight to combat the non-native aquatic plant populations that are infesting Florida's lakes, rivers and wetlands.

Time and money spent on managing invasive species can be saved in the first place by preventing the introduction and spread of invasive species in the state's waterways. Public cooperation is an essential part of restoring Florida's natural habitats.

Please read here about steps you can take to help prevent invasive aquatic plant problems.