When exotic aquatic weeds fill in canals, rivers, ponds, and lakes, residents typically demand aquatic plant management. That is where Aquatic Weed Control comes into play. Because our population has grown precipitously, aquatic weeds have become more of a noticed problem throughout our county, even in the previously remote sections of our area. Residents are, likewise, more likely to notice and question our Aquatic Weed Sprayers who are managing aquatic weeds. Indeed, public interest in water resource management has increased, our knowledge of environmental interactions has increased, and pesticide technology has become highly refined and carefully regulated.
The Federal Insecticide, Fungicide, and Rodenticide Act of 1979 (FIFRA), as administered by the United States Environmental Protection Agency (EPA), requires all persons who apply pesticides classified as restricted use be certified according to the provisions of the act or that they work under the supervision of a certified applicator. Commercial and public applicators must demonstrate a practical knowledge of the principles and practices of pest control and safe use of pesticides, accomplished through a standard examination. In addition, applicators using or supervising the use of any restricted use pesticides purposefully applied to standing or running water (excluding applicators performing public health related activities such as mosquito control) are required to pass an additional examination to demonstrate competency as described in the code of federal regulation as follows:
“Aquatic applicators shall demonstrate practical knowledge of the secondary effects which can be caused by improper application rates, incorrect formulations, and faulty application of restricted pesticides used in this category. They shall demonstrate practical knowledge of various water use situations and potential of downstream effects. Further, they must have practical knowledge concerning potential pesticide effects on plants, fish, birds, beneficial insects, and other organisms which may be present in aquatic environments. Applicants in this category must demonstrate practical knowledge of the principles of limited area application.”
Before any aquatic weed treatment takes place, our Aquatic Weed Inspector/Sprayers assess many environmental factors. The type of plant in the body of water to be treated is determined so the proper herbicide and concentration may be used (Common Aquatic Weeds). The potential for rain in close time proximity to spraying is assessed because some of the herbicides we utilize may be washed away before they are able to take effect on the plant. Wind is also taken into consideration to prevent any drift to desirable plants in the area. At less than optimal temperatures, plant growth slows down. Less than optimal temperatures may decrease herbicide absorption by the plant and, therefore, its efficacy. Water chemistry is tested before certain types treatments. We test for pH, conductivity, and the amount of dissolved oxygen in the water. These major factors and other minor ones affect how the herbicide reacts with the plants. Knowing the dissolved oxygen level before treatment helps to prevent fish kills which can occur when the target vegetation dies off quickly, using all available dissolved oxygen to decompose. The Aquatic Inspector/Sprayers are required to wear protective clothing to prevent exposure to the herbicides through their skin, clothing, and nose or mouth. They must follow the guidelines expressed on the herbicide label to ensure everyone’s safety.
When a waterway is to be treated, we utilize one of three types of vehicles: airboat, john boat, or marsh master. The airboat is able to quickly move around in the waterways. It is also able to traverse through densely vegetated waters. The john boat is utilized in areas of thinner vegetation. The marsh master, which looks similar to a tank, is used in shallow waters that have difficult banks to climb. It is also able to float. Occasionally, we do not use any vehicle, but spray or pull weeds by hand. This is usually in mitigated (rebuilt) wetlands or in very shallow waters.
Pesticide applications are not the only control means our Department utilizes. The USDA has discovered and released many biological control agents for some of our exotic aquatic weeds in Florida.
The USDA and the University of Florida are always investigating new biological agents to be used as control methods for our many nuisance exotic weeds. Our Department also relies on triploid grass carp in some areas. These grass carp are sterile and unable to reproduce. They eat the submerged aquatic weeds that are difficult to otherwise control. We stock these fish in specially gated channels to insure they stay where they are needed.