Tips on How to use Diquat Herbicide on Lakes and Ponds

Share this Article

Tips on How to use Diquat Herbicide on Lakes and Ponds

Tips on How to use Diquat Herbicide on Lakes and Ponds

Share this Article

Tips on How to use Diquat Herbicide on Lakes and Ponds

We often see lakes and ponds as we drive around the country from place to place but probably don’t realize how vital these bodies of water are to our livelihoods. Here you are about to know how to use diquat herbicide for our lakes and ponds.

Much like the air we breathe, lakes and ponds are highly important features of our lives and are mostly used for recreation activities such as swimming, boating, nature viewing, and fishing. 

However, before we get too far, what are some important facts about lakes and ponds?

First, lakes and ponds are:

  • Components of the Earth’s surface water are located in low spots in the countryside where surface water runoff and groundwater seepage can accumulate.
  • Are a part of Earth’s freshwater ecosystem which contains 0.8% of the global water resource, with the remaining 99.2% being marine water and polar ice caps.

Second, lakes are larger and deeper than ponds, and can be natural or artificial. For example:

  • An artificial lake can be constructed for industrial or agricultural use, for hydroelectric power generation, domestic water supply, or for aesthetic and recreational purposes.
  • An artificial pond can be constructed for aesthetic and recreational purposes, habitat restoration, architectural reasons, and breeding of fish or other aquatic species.

Some other important functions of lakes and ponds include:

  • Providing a habitat for a variety of wildlife species. 
  • Regulating the services of soil formation, biodiversity, groundwater recharge, and flood protection

Now that you see how our livelihood is within to lakes and ponds, let’s examine why it is vital that we protect these resources.

Are lakes and ponds threatened? 

Yes. Here are four major threats to lakes and ponds.

  • Human exploitation and development because a growing human population exerts pressure on freshwater ecosystems to maintain livelihoods.
  • Pollution from chemicals such as pesticides and fertilizers from farms and gasoline and oil from motor vehicles can have negative impacts on aquatic life, wildlife, and humans.
  • Aquatic invasive plant species are plants that can invade lakes and ponds and become dominant species within the invaded habitat. When this happens, a dispalcement of beneficial species may happen. Leading to a loss in biodiversity which will affect community structure and ecosystem functioning.
  • Climate change has resulted in altered timing and amount of water that flows to lakes and ponds. This flow of water to lakes and ponds causes flooding and an increase in the amount of water pollution.

The most challenging and costly threat comes from invasive plant species, especially those that invade aquatic systems. 

What are invasive plant species?

Invasive plant species are a unique class of plants that can enter a habitat. It also become quickly established, and change the nature of the habitat. It’s as if the invasive plants sneak in and try and act like they belong in or become ‘owners’ of their new habitat. 

As they are establishing, invasive plants are doing everything they can to get rid of native plant species. If you can’t get rid of them, the invasive plants may become the dominant species within the habitat.

Aquatic invasive plant species invade freshwater and marine ecosystems. They are a major concern for lake and pond managers because of the widespread negative impacts within freshwater ecosystems. Such as loss of recreational opportunities, fish kill, or stunted fish. 

Fortunately, research scientists have developed tools to confront the invasive aquatic species and rescue our fragile freshwater ecosystems. 

One such tool is diquat herbicide.

Here are some facts about diquat herbicide.

  • Diquat is a herbicide that is registered by the US Environmental Protection Agency for use in agriculture and aquatic systems. IT an control some of the major floating, submersed, and immersed aquatic weeds and some species of algae.
  • Diquat is a fast acting, non-selective contact herbicide. It will kill a wide variety of plants by disrupting cell membranes and interfering with photosynthesis. Treated plants will die within a week.
  • There are no restrictions on swimming or eating fish from water bodies treated with diquat. However, treated water should not be used for drinking by humans for one to three days. Depending on the concentration of diquat used in the treatment.
  • Pets and livestock can drink water treated with diquat after one day. Whereas irrigation of crops and ornamental plants can be after three to five days, respectively.
  • Diquat is strongly attracted to silt and clay particles in water. Therefore will not be effective in lakes and ponds with muddy water or where plants are covered with silt.
  • No significant short- or long-term impacts on fish and other aquatic organisms in lakes and ponds have been detected with diquat applications. However, walleye fish have been shown to display toxic symptoms when confined in water treated with diquat at label rates.

Now that we know a little bit about diquat, let’s see how to us it to control invasive aquatic plants.

Tips on how to use diquat to control invasive aquatic plants

  • Identify the invasive aquatic plant species targeted for control – this is critical for designing a good plan to manage the invasive plant, and the label will help determine if the plant can be controlled by diquat.
  • Identify desirable species within the lake and pond – since diquat is non-selective, this is a necessary step to ensure that desirable species are protected. The herbicide label will have information to aid in the identification of aquatic species that can be harmed by diquat. 
  • Determine the type of herbicide application that needs to be made. Which depends on whether the growth habit of the invasive aquatic plant to be controlled is emergent, submerged, or floating.

Necessary Precautions When Applying Diquat To Lakes & Ponds Include:

  • Bottom sediment’s distrubtion must not happen during treatment which may occur with an outboard motor. Sediment containing silt and clay particles will tie up the diquat molecules and render the treatment ineffective. 
  • Treat infested lakes or ponds in stages, e.g., ⅓ to ½ of the body of water to prevent excess amounts of decomposing vegetation. It may result in low oxygen levels in the water. Low oxygen levels can be lethal to fish and other aquatic organisms. Application for untreated lake and pond areascan be diquat 10 – 14 days after the first treatment.
  • Pesticide applicators should wear the appropriate amount of personal protective equipment (PPE) when applying diquat, in accordance with label instructions. Diquat can cause severe skin and eye irritation. Also it may be toxic or lead to fatality if absorbed through skin, inhaled, or swallowed. 

Use adjuvants to improve control 

Select the best surfactant and/or adjuvant to maximize herbicide efficacy and invasive aquatic plant species control. 

  • For improved control of floating invasive aquatic plant species, use a nonionic surfactant, e.g., Brewer International’s Cide Kick nonionic surfactant. 
    • Cide Kick formulation is 100% d’limonene which is a low viscosity oil and byproduct of the citrus industry. 
    • It is a wetting agent, activator and protectant combined. 
    • Cide Kick helps herbicide uptake by breaking down the waxy cuticles on leaf surfaces and penetration of the bud and bark area. 
    • It is compatible with most aquatic and terrestrial herbicides, insecticides, and other pesticides.  
  • For more information on Cide Kick, read: https://brewerint.com/product-spotlight/cide-kick-nonionic-surfactant-for-invasive-aquatic-plants/ Blogpost. 
  • For improved control of submersed invasive aquatic plant species, use a nonionic sinking and drift control agent, e.g., Brewer International’s Polyan nonionic sinking and drift control agent.
    • As a nonionic surfactant, Polyan helps break down the waxy cuticle of leaf surfaces which enables more effective herbicide uptake and improved control.
    • Polyan enables the pesticide to bond and stick on plant leaf surfaces. 
    • Polyan forms viscous spray droplets when mixed with herbicide. Viscous herbicide spray droplets sink to the bottom in aquatic systems to effectively be in contact with submersed invasive plant species with little off-target drift. 

For additional information on managing aquatic plants, check out the following blogs: 


Brewer International (https://brewerint.com/) has been a leader in land and water chemistry since the 1980’s and for over 40 years has proudly served it’s national and regional distributors. 

Our products are used widely across the United States in agriculture, aquatics, forestry, rights of way, and land management. 

Our customers trust our dedication to quality ingredients, tried and true formulas, and positive outcomes.

Featured Posts

Subscribe To Our Newsletter

Ready to Start Something Great?

Got questions? We’re here to help you make the right call. Let’s chat!