Diquat Herbicide: An Easy Guide on What It Is, How to Mix It, and How to Use It

Diquat Herbicide

Alligare Diquat Herbicide is perfect for ponds, lakes, reservoirs, marshes, drainage ditches, canals, and streams on your farm. It helps remove weeds that grow near or in the water.

In this article, I will explain the simple steps required to use, mix, and apply this herbicide.

It’s specially designed to fight aquatic weeds.

What is Diquat Herbicide?

Diquat is a non-selective, post-emergent herbicide with fast-acting action that effectively controls floating and marginal weeds, as well as submerged weeds.

Diquat Active Ingredient

The active ingredient of Diquat herbicide is also called diquat dibromide. The herbicide contains 2 lbs of diquat cation per gallon, which is equivalent to 3.73 lbs of diquat dibromide per gallon.

How does Diquat Herbicide work?

The mode of action of Diquat herbicide involves damaging the cell membranes and disrupting the photosynthesis process in unwanted plants.

This herbicide is absorbed by plants and moves throughout the plant’s system, leading to rapid desiccation and death of the target plant.

If applied correctly, it can take 7 to 9 days for the Diquat herbicide to work and show visible effects on target plants.

Where to apply

Diquat herbicide is used for pond management within the agricultural sector, offering effective control over weeds. You can apply Diquat herbicide in waters like ponds, lakes, reservoirs, canals, streams, rivers, bayous, and drainage ditches.

Other types of areas where you can use it are:

  • non-crop areas on farms.
  • farm areas where nothing has been planted yet.
  • commercial greenhouses and nurseries.
  • dominant established turfgrasses like bermudagrass and zoysiagrass.
  • landscape, industrial, recreational, commercial, residential, and public areas.
  • ornamental seed crops like flowers and bulbs.
  • turf renovation, except for commercial sod farms.

When to apply Diquat Herbicide

You can apply Diquat herbicide in spring or early summer when the weeds are young but still actively growing, or when the water temperatures are above 50°F (10°C) or higher.

To ensure a successful application, it is important to keep in mind not to apply the herbicide:

  • when the wind direction is variable and inversion conditions are high.
  • when there are high levels of wind, water flow, or wave action.
  • when temperatures are above 85°F (29°C).
  • when rain is forecasted.
  • in dusty conditions. Dust can coat the target weeds, which may result in the limited effectiveness of the product.

How to use Diquat herbicide

To use the Diquat herbicide correctly and ensure you benefit from its full effectiveness, you must follow these next steps:

  1. Always start by reading the product label. You have to become aware of the product instructions, guidelines, precautions, and recommended application rates.
  2. Make sure that the timing is appropriate for applying Diquat herbicide and that the weeds are at a suitable stage for treatment.

    You can apply it in spring or early summer when the weeds are young and have a height ranging from 1 to a maximum of 6 inches (2,5-15 cm).
  3. Prepare the area accordingly. When getting ready to spray with Diquat herbicide, avoid mowing or grazing the area before application. If you have already mowed or grazed, wait until the weeds regrow to a height of 2 to 4 inches (5-10 cm) before applying the herbicide.
  4. Choose a day with favorable weather conditions. Avoid applying the herbicide when humidity is low, wind speeds are high, temperatures are extremely high or near freezing, or when rain is predicted within the next 4 hours after application.

    Equip yourself with the appropriate personal protective equipment (PPE) for herbicide application.

    For the Diquard herbicide application, you need the following PPE:
    – coveralls over a short-sleeved shirt and short pants or coveralls over a long-sleeved shirt and long pants
    – chemical-resistant gloves
    – chemical-resistant footwear plus socks
    – protective eyewear
    – chemical-resistant headgear for overhead exposure
    – chemical-resistant apron when cleaning equipment, mixing, or loading
    – face shield when mixing or loading

    Barrier laminate, butyl rubber (with a thickness exceeding 14 mils), and nitrile rubber (with a thickness exceeding 14 mils) are among the chemical-resistant materials of this product.
  5. Mix the herbicide in accordance with the product instructions. Measure the required amount of Diquat herbicide according to the recommended dosage on the product label.
  6. Pour it into the sprayer tank, ensuring proper mixing and agitation to achieve a uniform solution. If you are targeting floating and marginal weeds, you have various application methods available, including airboats, airplanes, backpacks, spray handguns, and helicopters. Additionally, for these types of weeds, you can utilize broadcast and spot treatments.

    For controlling submerged weeds that have reached the water’s surface, the application is performed using boom trailing hoses equipped with nozzle tips. These hoses are used to direct the diluted spray below the water surface. This method ensures adequate coverage and effectiveness in treating submerged weeds.
  7. Cover the target areas evenly. Pay attention to ensure uniform coverage and avoid overlapping or missing spots.
  8. After application, properly clean the sprayer and also the protective gear.

Alligare diquat herbicide mixing instructions

This herbicide is extremely user-friendly and requires minimal effort to prepare for spraying.

The mixing instructions for Alligare Diquat herbicide are the following:

  1. Determine the appropriate amount of water to cover the target area.
  2. Add the correct amount of Diquat herbicide to the water.
  3. Continuously mix the solution to achieve thorough dispersion.
  4. Include a nonionic surfactant for herbicides (NIS) with a surface active ingredient of 75% or more. Ensure that the NIS label specifies compatibility with Diquat.
  5. Thoroughly mix the solution again until it is well-blended.

Diquat Herbicide Mix Ratio

Floating and marginal weeds

The Diquat mix ratio for floating and marginal weeds is 2 quarts of herbicide per 100 gallons of water to create a 0.5% solution.

Also, you need to add an approved aquatic wetting agent at a concentration of 0.25-1.0% v/v, which corresponds to 1 quart to 1 gallon of the wetting agent per 100 gallons of water in the spray carrier.

This is available only for spot treatment.

For broadcast treatment to control floating and marginal plants, you need to mix 0.5 to 2.0 gallons of Diquat herbicide per surface acre in the spray carrier, along with 16 to 32 ounces of an approved aquatic wetting agent.

Submerged weeds

In the case of controlling submerged weeds, you have to use 0.5 to 2.0 gallons of herbicide per surface acre in water, and you need to reapply the application after 14 or 21 days from the first one for effective weed control.

You can also use the mix ratio from the Table 1:

Table 1. Gallons of Alligare Diquat Herbicide per Surface Acre
Average Water Depth 1 Foot 2 Feet 3 Feet 4 Feet
1 gallon/acre rate 0.25 gal. 0.50 gal. 0.75 gal. 1.0 gal.
2 gallon/acre rate 0.50 gal. 1.0 gal. 1.5 gals. 2.0 gals

Commercial greenhouses and nurseries

Furthermore, the mix ratio of Diquat herbicide for commercial greenhouses and nurseries is 1 to 2 quarts per 100 gallons of water for spot spraying.

Additionally, you need to add a nonionic surfactant with a concentration of 75% or higher.

For broadcast application, you need 1 to 2 quarts of herbicide in 15 gallons of water or more per acre. You should also add a nonionic surfactant at the rate recommended on the product label, per 100 gallons of spray mixture.

Dormant turfgrasses

When spraying dormant turfgrasses, you need to use 1 to 2 pints per acre in 20 gallons of water, along with a nonionic surfactant.

It is recommended to follow the mix ratio of the surfactant per 100 gallons of the spray mixture.

Landscape, industrial, recreational, and public areas

For zones such as lawns, golf courses, roadsides, walkways, patios, driveways, etc., use 1 to 2 pints of herbicide per acre for broadcast application.

In addition to this, you have to include a nonionic surfactant at the recommended rate in 20 to 100 gallons of water.

Weeds controlled by Diquat herbicide

Diquat herbicide can control floating and marginal weeds such as water lettuce, water hyacinth, duckweed, salvinia, pennywort, frog’s bit, and cattails, as well as submersed weeds like bladderwort, coontail, hydrilla, watermilfoils, pondweeds, Brazilian elodea, naiad, algae, and elodea.

It is also effective against weeds in dormant turfgrass, including annual bluegrass, little barley, bromes (including rescue grass and six-week fescue), henbit, buttercup, and Carolina geranium.

Application Precautions and Restrictions

Diquat herbicide should be used with caution, carefully following the restrictions and limitations, to ensure proper and safe usage of the herbicide.

  • Before using Diquat herbicide, ensure that you have obtained all the necessary permits required for its use and application.
  • Diquat herbicide should only be applied by individuals who hold a certification for aquatic pest control issued by the State or Local government.
  • It is important not to apply Diquat herbicide in areas where commercial fish processing for fish protein concentrate or fish meal production occurs.
  • Do not use this herbicide in any irrigation system.
  • After spraying the Diquat herbicide, prevent livestock from grazing in the treated area. Additionally, avoid feeding your livestock with turf or feed that has been sprayed with this herbicide.

In Table 2, you can also find the water use restriction for the herbicide:

Table 2. Water Use Restrictions Following Applications of Alligare Diquat Herbicide
TYPE OF WATER 2 gals./surface acre 1 gal./surface acre 0.75 gal./surface acre 0.50 gal./surface acre Spot Spray (<0.5 gal./surface acre)†
Drinking 3 days 2 days 2 days 1 day 1 day
Fishing and Swimming 0 0 0 0 0
Livestock/Domestic Animals Consumption 1 day 1 day 1 day 1 day 1 day
Spray Tank Applications†† and Irrigation to Turf and Landscape Ornamentals 3 days 2 days 2 days 1 day 1 day
Spray Tank Applications†† and Irrigation to Food Crops and Production Ornamentals 5 days 5 days 5 days 5 days 5 days

How to store

You should store the herbicide in its original container and avoid using food or drink containers for concentrate or dilute mixtures.

Also, do not store or transport the pesticide near feed or food items. At the same time, make sure that the temperatures of the storage room are above 32°F (0°C).


Is Diquat herbicide safe for fish?

Diquat herbicide is safe for fish and other aquatic life when applied correctly, following all the guidelines stated on the product label.

According to the label instructions, when treating water bodies such as ponds or lakes, it is recommended to apply the herbicide to only 1/3 to 1/2 of the water body area at a time and reapply after 14 days.

By following these guidelines, you can prevent the depletion of oxygen in the water body, which can result from the decomposition of dead weeds and ultimately lead to fish suffocation.

Is there an alternative to Diquat herbicide?

An alternative to the Diquat herbicide is the Reward herbicide, which contains the same active ingredient.

Is Diquat herbicide safe for bees?

While Diquat herbicide is generally considered safe for bees, you should be cautious when spraying it near lakes or ponds where bees may drink.

To minimize potential exposure, it is recommended to schedule the application on a day or time when bees are less active or not present in the area 24 hours after spraying with herbicide.

Can Diquat herbicide be tank-mixed with other herbicides?

The label of Diquat states that it can be tank-mixed with other herbicides if compatibility with Diquat is specified on the label of the other herbicide.

It is important to check the label of the herbicide you wish to mix with Diquat and verify if they can be safely combined.

How much does Diquat herbicide cost?

Diquat herbicide costs about $100 per gallon and can also be purchased online, for example, on Amazon.

Related video:

If you have any other concerns or questions about Diquat herbicides, please don’t hesitate to contact me using the comment form below. I will gladly respond as soon as possible.

About the author: Dani Martelli
Dani FarmerDB

My name is Dani and I am a farmer with 10 years of experience. I will share with you everything about farming from processes, tips, machines, and more. Farming for me is not just a job but a way of life. Keep reading ...

  1. I live on a lake in the Orlando florida area and the last couple of years pondweed has overtaken our lake. My lakefront problem area is in the 6-8 ft depth area and is about a 50×50 ft area. Can I use Diquat to control it? I have 1 gallon. If so should i mix in some liquid soap such as Dawn? The weeds are growing on the surface, rooted at the bottom. Use a sprayer with the wand underwater and then mix water area with an oar? Or something different? Thanks in advance for your insight!

    • Hi,

      Before using it, you need to make sure that the weeds you want to target can be effectively controlled with this herbicide. Have you identified the specific type of weed from your pond?

      Diquat herbicide is only effective against certain submerged weeds: Bladderwort, Hydrilla, Watermilfoils, Pondweeds, Coontail, Elodea, Brazilian Elodea, Nalad, and Algae.

      If you have one of these weeds, then you can certainly use Diquat.

      For an area measuring 50×50 ft with a depth of 6-8 ft, you should use 0.03 to 0.12 gallons of Diquat herbicide, and consider reapplication after 14 to 21 days.

      If you have a mixture of different weeds, you can use a slightly higher amount. This amount is applicable when there are no fish present in the pond. If you do have fish, take care to apply this herbicide to only half of the water body area.

      You can attempt to substitute liquid soap instead of a dedicated surfactant; it might provide you with good results.

      Regarding the application method, Diquat can be applied to the surface but also directly to the bottom. The label suggests both ways as being correct.

      You can spray it to the surface by making sure that the entire area is very well covered with the herbicide.

      But if you want to get to the bottom, you can use weighted hoses to carry the herbicide solution close to the bottom of the water where the weeds are rooted. You can use something else improvised as long as it helps you get down to the roots of the weeds.

      I hope my answer is helpful to you. If you have any more questions, don’t hesitate to write to me in the comments section.

    • Hi,

      You can water the flowers with lake water that had Diquat herbicide in it.

      But to keep the flowers safe and healthy, I suggest you water only 2-3 flowers and see how they do for a few days. If they stay okay, you can water the rest of the flowers without worries.

      Basically, if Diquat was used a while ago, it shouldn’t be a problem.

Leave a Comment