Herbicides and Algaecides
US EPA registered and state-approved herbicides can be highly effective in areas where mechanical and biological methods are impractical, or when invasive species, which spread quickly through fragmentation, are of concern.
Aquatic herbicides and algaecides have been used successfully for several decades. Millions of acres of ponds/lakes are treated annually throughout the United States, and several thousand acres of nuisance aquatic vegetation are managed here in the Northeast with herbicides and algaecides. Herbicides typically work by inhibiting specific plant processes or degrading specific plant structures, such as interfering with photosynthesis or disrupting the cell wall of plants, which leads to their natural decay. This mode of action allows herbicides to have very high effectiveness against targeted species while being non-toxic, or minimally toxic, to animals and humans.
Ponds or lakes that are effectively managed over a number of years with aquatic herbicides may have a healthier aquatic flora and fauna. Plants are managed rather than clipped, so control can often be relatively long-term (greater than one year). As opposed to other techniques, herbicides affect the plant and its process for reproduction. Thus, this technique can significantly retard dispersion of nuisance macrophytes before they become well established in a lake. Early season treatments are often performed to minimize plant growth and help reduce nutrient recycling later in the season. Many herbicides have been approved for use by the Federal EPA and governing bodies of individual states for decades.
US EPA registered and state-approved herbicides can be highly effective in areas where mechanical and biological methods are impractical, or when invasive species, which spread quickly through fragmentation, are of concern. Unlike mechanical techniques, which work on a year-to-year basis by ‘mowing’ areas of plant growth, herbicides manage vegetation by degrading plant structures such as cell walls or inhibiting vital processes such as photosynthesis. This allows for relatively long-term control and limits or eliminates the chance of reproduction through fragmentation. Use of herbicides can also effectively manage aquatic plants without adverse effects to non-target organisms.
Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), herbicides must pass a rigorous review process by the Environmental Protection Agency (EPA), which includes more than 100 different scientific studies and tests from herbicide manufactures. The results must show that the herbicide can be used with a reasonable certainty of no harm to human health and without posing unreasonable risks to the environment, when used according to label specifications. Products registered by the EPA undergo a continuous review process to ensure that the highest standards are met. Use of these EPA registered products is further regulated by the individual states, which may require their own approval process.
There are two main categories of herbicides – contact and systemic. Contact herbicides affect only the portion of the plant that comes into contact with the herbicide, while systemic herbicides are taken up by the plant and translocated throughout the plant. Contact herbicides generally do not affect the root systems of plants, and are therefore more suited for management of annual species. Systemic herbicides work more slowly than contact herbicides, as the herbicide moves throughout the plant; however, the entire plant, along with the root system is affected, limiting the possibility of re-infestation. With accurate timing, both contact and systemic herbicides have the ability to reduce reproduction via seeds and fragmentation.