How to Apply Aquatic Herbicides

Before applying aquatic herbicides, consider some questions: What type(s) of weeds do you have? What is the treatment area (square footage and average depth)? What are your realistic expectations for the area? Once you have answered these questions, you can move to action: purchase a product that is labeled for effective control of the target weed(s), read the label, prepare your equipment, and finally perform the aquatic herbicide application.

Aquatic Herbicides Are Safe

Many people ask if aquatic herbicides are safe. The short answer is yes. Of course, there are guidelines to follow to ensure that they are safe, just as there are guidelines to follow with household cleaners or even toothpaste. The Environmental Protection Agency (EPA) has many standards that must be adhered to for herbicides to be approved and registered. The herbicides Lake Restoration sells are EPA-registered, meaning they have met the required standards. Dibrox®, our most popular herbicide, has been on the market since 2015. It is a broad-spectrum contact herbicide that controls a wide range of submerged and floating weeds. Customers trust that Lake Restoration products will safely and effectively manage weed growth.

Plan Your Aquatic Herbicide Application

There are multiple steps to follow when applying aquatic herbicides, and most of them are before the actual application. Understanding the specifics of your water and developing an effective treatment plan is important for effective control of target weeds. Calculating your treatment area and identifying the target weeds are most crucial before applying herbicides. This way, you will be able to use the proper herbicide for the plants you have, and the correct amount of this herbicide for the area you are treating.

First, determine your treatment area; this includes square footage or acreage as well as average depth. The treatment area must include the weeds you are targeting. If you are going to treat sections of the pond at a time, calculate the square footage and average depth of each section and write them down.


The second step is to identify the weeds you want to control. One way to identify weeds in your pond or lake is to use Lake Restoration’s Aquatic Plant ID tool. Another way is to take photos of them and send them to specialists. When a specialist gets back to you, he/she will likely ask some clarifying questions to help narrow down the type of weed you are looking at. You can email your photos to [email protected] for our product specialists to help you with identifying weeds. You can also have a local university’s agriculture department or your local department of agriculture look at your weeds. No matter which route you take to identify the plants, looking at them as a group, close-up as individuals, and taking descriptive notes will help. Once you have determined your treatment area and identified target weeds, you are ready to purchase products.

Read the Product Label

Understanding herbicide labels is not as complicated as it looks. EPA-approved herbicide labels generally contain similar sections. After the name of the product, there is a brief description of what it is used for and in what type of environments. Then you will find the ingredients and some cautions along with general guidelines. Read the first aid/safety recommendations, precautions, and environmental hazards. Remember that these statements are precautionary. In extreme cases, the toothpaste you use daily can be harmful, yet you likely give no second thought to putting it in your mouth. There are often multiple “Directions for Use” sections, as many herbicides are labeled for various uses. Find the “Aquatic Use” section; this is where you will focus your reading. Read through the restrictions and precautions, keeping in mind that you should re-read them after determining which statements apply to your situation.

Because you have properly identified the plants you wish to target and have purchased a product specifically for controlling those weeds, you should find them on the lists of weeds controlled by the product. If there are asterisks or notes for your target species, be sure to read them thoroughly as they are there to help you best control the plants. Find the application method that suits your needs and will best control your weeds.

Many product labels have charts for application rates. It can be difficult to know what rate, for example parts per billion (ppb), you should use. Choosing a middle rate is generally a good place to start. Higher rates may be appropriate when you are treating a small area, tough to control weeds, or expect some water movement out of the area. Many contact herbicides, such as Dibrox® and Flumigard®, need to be diluted with water and sprayed over the treatment area. The main reason for diluting herbicides with water is to distribute the amount evenly across the treatment area. Herbicide labels follow a similar pattern and should be read before applying the products.

Apply Aquatic Herbicide

Once you have familiarized yourself with the information contained on the label, you are ready to apply the herbicide to control your target weed or species. Note that this discussion is for contact herbicides like Dibrox®, Diquat, Aquathol® K, and Flumigard®. Check the weather to plan for a sunny and calm morning for application. When the day comes, have your personal protection equipment (PPE) and application equipment ready. For many herbicides, the application equipment will include a sprayer, measuring device, and water source. Set your sprayer droplet size according to the guidelines on the herbicide label. Our recommended dilution for Dibrox® is 16 oz. per gallon of water in the sprayer to treat an area with an average depth of 4 feet.

If your herbicide is granular, such as Hydrothol®, Navigate or Aquathol® Super K, you will likely use a broadcast spreader to get even coverage of the product. Again, the herbicide label will offer guidelines on how many pounds to use given your target area and depth. A scale can help with granular herbicides: weigh the amount you plan to use then split it in half, along with your treatment area. Treating half the area with half the product will help you get more even coverage.

If you do not want to spray or do not have the necessary equipment, our TORMADA product application boat can be used to treat ponds or lakeshores. The TORMADA has a one-gallon tank that you fill with Dibrox® or another herbicide (full strength). Then use the remote control to drive the fan-powered boat in a zig-zag pattern 10-15 feet apart. Because the fan is mounted on top of the TORMADA, the boat will glide over weeds to get product across your entire treatment area.

After applying herbicides, the most difficult part for many people is waiting to see results. Some product labels give a general idea of how long it can take to see visible results. You can also ask Lake Restoration’s product specialists how much time to wait for results and how long to wait before re-treatment. Managing lake or pond weeds is an ongoing commitment. As with most tasks, it gets easier with more knowledge and practice.


Frequently Asked Questions from TAMU AquaPlant

Aquatic Herbicides: Essential Information for New Applicators from OSU Extension