Below you will find a few of the most frequently asked questions and answers regarding aquatic plant management. Do you have a question about invasive plant management? Please contact the Center and we will be happy to connect you with an expert!
All herbicides should be handled with great care, especially in their concentrated form. Once diluted according to label instructions, aquatic herbicides are considered safe for the specified use by the U.S. Environmental Protection Agency and the Florida Department of Agriculture and Consumer Services, who ensure that they meet the most stringent safety standards under federal and state regulations. “Restricted use” herbicides are not permitted for use in water.
The Environmental Protection Agency (EPA) explains that when a registered herbicide is used according to the label directions, it will cause no unreasonable adverse effects on human health or the environment. All pesticides undergo years of testing, review, and evaluation by the EPA before they can be used. One of the specific criteria for review is “effects to non-target organisms”. Birds, mammals, fish, and invertebrates are all considered “non-target organisms”. Since herbicides are only used to manage plants, tests have shown minimal impacts on these non-target organisms.
When used according to the product label, herbicides have not been shown to cause fish sores. Fish sores can have many causes but usually result from stress or an infection.
Depending on what herbicide you need, there are a variety of options ranging from big-box stores, farm and garden stores, or professional pesticide distributor companies. When buying from big-box or farm and garden stores, the products may already be mixed at the appropriate concentration for use around your home and landscape. Professional distributors usually have more concentrated products, packaged differently for large-scale applications. If you have a property with several acres of invasive plants that need management, it might be more efficient to hire a professional contractor. A permit from a state, county, or local agency may be required.
Maybe, maybe not...it depends on the label. When the EPA registers herbicides, they register them for use sites and not for individual plants. For example, some herbicides are labeled for aquatic use only, while others can be used in water as well as on lawns. Always read and follow the instructions on the herbicide label, since it describes where the product can be used safely. If you are unsure about which herbicide to use, consider consulting with your local UF/IFAS Extension office for guidance on your specific situation. A permit may be required for some applications.
Both recognize the importance of sustainable and environmentally friendly practices. However, their management goals differ when it comes to using herbicides. Agriculture management goals relate to maximizing crop production by reducing weedy plants around their desired crop. Aquatic and natural areas focus on enhancing biodiversity by managing nuisance and invasive plants to allow desirable native species to thrive.
Proactive aquatic plant management refers to the measures taken (such as herbicide treatments) to minimize the impact of invasive and nuisance plants by intervening before large problems develop, to protect waterbodies and the biodiversity present in them. While proactive management requires more frequent presence on the lake, treating fewer plants results in less herbicide use over time, and fewer plants decaying and releasing nutrients.
On the other hand, a reactive strategy involves waiting for plants to grow to problematic levels. Managing large amounts of plants at one time can lead to low dissolved oxygen as the plants decay, while also causing algae blooms with the mass release of nutrients from the decaying plants. Proactive management allows managers to get ahead of the invasive and nuisance plants before they become a problem in order to promote the growth of native plants and future enjoyment of the waterbody.
Algae blooms usually occur when there are more nutrients in the water than the plants and critters that use them. They can happen when heavy rains wash fertilizer and organic matter from surrounding lands into the water, or when large storms stir up the muck on lake bottoms and release stored nutrients.
It is also possible to see algae blooms after an herbicide application. However, most aquatic herbicides do not add nutrients to the water. Instead, the reason is a result of treated plants releasing nutrients into the environment when they decay. Algae are usually the first to access these newly available nutrients and a bloom can result. The best way to minimize this is to adopt a proactive management strategy that never allows invasive plants to build up to high numbers. Managing fewer plants frequently reduces nutrient release and helps reduce blooms associated with plant management.
The ability to target a plant species for removal through herbicide treatments is called "selectivity". Selectivity is often based on traits that are unique to plant species that make them either more sensitive to or tolerant of the herbicide. For example, some plants metabolize (or breakdown) certain herbicides very quickly and are able to survive the treatment. Therefore, knowing these differences in how plant species respond to specific herbicides allows skilled managers to safely use herbicides that will effectively remove target plants and leave the others.
