Surfactant for Herbicides: What It Is, How to Use It, When to Apply, and Tips

If you’ve ever dealt with weeds and used herbicides, you’ve definitely come across the term surfactant for herbicides, at least subtly.

Surfactant for herbicides represents one of the key “ingredients” that you can add to your herbicide in order to give it an excellent boost of performance.

Since you have reached this page, I am sure you would like to find out much more information about surfactants for herbicides such as their types, and best practices for their use to maximize herbicide performance and minimize potential risks.

So let’s not waste any more time and go directly to the subject.

How surfactant works

What is a surfactant for herbicides?

Surfactant is a chemical additive that alters another substance’s chemical or physical properties. It is also the shortened form of the ‘surface active agent’.

Surfactants are classified as activator adjuvants, and they are also known as wetters/spreaders.

Surfactant contains long molecules that have a head and a tail. The head of the molecule is hydrophilic, which means it is attracted to water molecules. It is also known as ‘water-loving’.

The tail of the molecule is hydrophobic and repels the water molecules. As a result, the surfactant has both water-loving and water-repelling properties.

Types of surfactants

There are four different types of surfactants:

  • anionic
  • cationic
  • non-ionic
  • amphoteric surfactants

However, I want to inform you that there is a new group of surfactants called organosilicone. It is an extra addition to the type above.

But what distinguishes these four types of surfactants? Each type of surfactant is differentiated by the electrical charge of the hydrophilic head, which can be positive, negative, or neutral.

Anionic surfactants have a negative charge on their hydrophilic end, while cationic surfactants have a positive charge on their hydrophilic end. Amphoteric surfactants have a dual charge, being both negative and positive. Last, but not least, the non-ionic surfactants have a neutral hydrophilic end.

But what type of surfactant can you use with herbicide?

Of all the types of surfactants above, the most commonly used and recommended for use with most registered herbicides is the non-ionic surfactant.

The others types of surfactants are not used in combination with herbicides because they can be harmful or even toxic to plants.

Considered to be the safest, non-ionic surfactant, also known as NSI, has no electrical charge and does not harm plants. It is composed of alcohols and/or fatty acids, which help improve the absorption of herbicides in plant tissue by reducing surface tension.

The non-ionic surfactant is effective at reducing surface tension due to its great wetting and emulsifying properties.

Most herbicides are compatible with non-ionic surfactants.

How surfactant works

The surfactant works by reducing the surface tension of the herbicides.

In the case of weeds with shiny, waxy surfaces, the surfactant-free herbicide solution sprayed on them does not do much.

When you apply herbicide solution on the waxy weeds, it does not stick to the plant’s surface.

The herbicide solution drips onto the ground instead of staying on the weeds’ surface. Therefore, the herbicide does not penetrate the waxy layer of the cuticle and has zero effect.

When you use surfactant, it helps the herbicide stick to the surface of the plant and to penetrate through the waxy layer.

In addition to facilitating the decomposition of the waxy layer of the weed’s cuticle, the surfactant prevents the herbicide from running off the weed. This improved adhesion of the herbicide to the weed surface allows it to remain in contact with the weed for a longer period.

This improves the effectiveness of the herbicide against the targeted weed.

How surfactant works
How surfactant works

Why use surfactant for herbicides

In short, a surfactant increases the effectiveness of herbicides.

Below are other reasons why surfactant is used with herbicides:

  1. Surfactant improves the wetting properties of herbicides. Some herbicides are water-repellent and do not stay on the surface of the plant when sprayed. This is where the surfactant comes in, which reduces the surface tension of water, helping to spread the herbicide evenly on the plant’s surface.
  2. Surfactant facilitates the penetration of the herbicide into the plant tissues. It helps the herbicide penetrate the plant’s waxy layer, which prevents the herbicide from penetrating the plant.
  3. Surfactant ensures the uniform distribution of the active substance in the plant. The herbicide acts faster and controls weeds more effectively.
  4. Surfactant ensures the effectiveness of herbicides in unfavorable conditions such as those with low, high temperatures, or even drought.
  5. Surfactant reduces the amount of herbicide needed by improving the herbicide adhesion to the plant surface.

When to use surfactant for herbicides

You should use surfactant for herbicide when:

  • You want to apply a liquid herbicide
  • You are looking to enhance the efficacy of a herbicide
  • You are dealing with glossy, waxy, hairy surfaces, and you want to improve the herbicide’s ability to adhere to these surfaces
  • You want to spray herbicides in high humidity conditions. Under high humidity, the weeds are more difficult to be handled.

However, never act before consulting the herbicide label. Why? Because certain herbicides already contain surfactants. Therefore, you do not need to add more.

How to use surfactant for herbicide

There are two common ways of using surfactants with herbicides:
1. Applying the surfactant before the herbicide
This method involves first applying only the surfactant alone to the weeds.

Follow the following steps:

  1. Combine herbicide surfactant with water
  2. Put the resulting solution in a herbicide applicator
  3. Spray the solution on the target weeds.
  4. Wait for the sprayed herbicide surfactant to dry
  5. Prepare the herbicide solution
  6. Spread the herbicide solution on the same target weeds that you applied surfactant for the herbicide.

2. Mixing the surfactant with the herbicide
This is my favorite method of using surfactants with herbicides, and I recommend it to you too. It is easier, more practical, and requires less time.

The following steps should be followed here:

  1. Combine the surfactant with the herbicide in a container. Read the label and use the recommended mix rate of both.
  2. Mix the solution very well
  3. Put the resulting solution in a herbicide applicator
  4. Spread the herbicide solution with surfactant on the target weeds.

Tips for applying surfactant for herbicides

  • Always use the right application equipment for herbicides. This keeps you safe when you handle chemical solutions.
  • When you add surfactant to the herbicide, mix the solution very well. The surfactant for herbicides must be fully incorporated and evenly distributed.
  • Spray the surfactant for herbicides directly on the target weeds. Apply the solution evenly and uniformly on all sides of the weed.
  • Spray enough solution on the weed. Make sure leaves are completely covered in surfactant for herbicides.
  • Apply the herbicide and surfactant at the right time. The best is to spray it in spring when the weeds start to emerge, or in fall when the weeds prepare for winter by storing nutrients.
  • Avoid applying surfactant for herbicides in windy or rainy conditions, as well as drought ones.

List of herbicides you can add surfactant to

You can add surfactant to the following herbicides:

  • Tenacity herbicide. According to the manufacturer, you can use Tenacity herbicide with non-ionic surfactant in postemergence applications.
  • Celsius WG herbicide. You can add surfactant to the Celsius WG. The label recommends a non-ionic surfactant ) at 0.25% v/v to the spray solution, but only when
    the temperatures do not exceed 90°F.

List of herbicides you cannot add surfactant to

  • Blindside herbicide. Unless prior experience has demonstrated that the combination is physically compatible and will not harm the specific type of grass, do not use surfactant with Blindside herbicide.

Homemade surfactant and dish soap as herbicide surfactant

Can you use dish soap as a surfactant? How can you make a homemade herbicide surfactant? I have come across these questions many times.

The answer to all these questions is yes.

Yes, you can use dish soap as a surfactant if you want a more organic and pure solution. Yes, you can make your own homemade herbicide surfactant if you want to obtain a DIY solution to your weed problem.

Now, let’s take about the results you will obtain by using these methods. In short, the results of using these DIY surfactants for herbicides will be extremely mediocre, or even zero.

If you have a small green corner or a small garden and you definitely want to keep it as natural as possible by using natural surfactants for herbicides, you can definitely try it. Even with mediocre results, being a smaller space, you can resort to pulling weeds in the end – and you have your organic green space.

But, in the case of large agricultural areas or difficult-to-control weeds, you should definitely follow the label recommendations and use a special surfactant for herbicides.

I am all for natural and organic, but when you deal with stubborn weeds and with a production area of hundreds of acres, you need something 100% effective.

How much surfactant for herbicides should you use per gallon

In general, surfactants are added to herbicides at a rate of a minimum of 0.25% to a maximum of 1% by volume. This means that you should use 1 teaspoonful of surfactant for herbicide per gallon.

My advice is always to read the label and follow the exact instructions and recommended usage rates when applying surfactants to herbicides.

The amount of surfactant per gallon can vary depending on the specific herbicide.

So, be careful not to use more than you need, which leads me to another question that is often addressed to me.

Can you use too much surfactant?

Yes, there is a risk that you use too much surfactant for herbicides, which can cause negative effects on the herbicide performance. It can also cause health problems for other plants.

Some of the common issues when using too much surfactant with herbicides are:

  • Phytotoxicity – This is something like an overdose for plants. You can identify phytotoxicity by the symptoms that appear like chlorosis and necrosis.
  • Drift – Too much surfactant in herbicides leads to drift because the surfactant makes the solution droplets too fine. This leads to the death of the other surrounding plants that you do not want to target.
  • Low effectiveness of herbicide – Too much surfactant in herbicides reduces the effect of the herbicide.

Price of surfactant for herbicides

The price range of surfactant for herbicides is between $20 to $50. The price varies on factors like the brand and the quantity purchased.

FAQ

Do surfactants help herbicide drying time on leaves?

Yes, surfactants help to reduce the drying time of herbicides on leaves.

The surfactant helps the herbicide break the glossy layer of the leaves and infiltrate into the plant’s cuticle, which can reduce the drying time.


Is surfactant for herbicide safe for pets, livestock, or other animals?

The surfactant for herbicide is safe for pets, livestock, and other animals if it is completely dried and used correctly.

The surfactant for herbicide becomes toxic to animals when ingested, absorbed through the skin, or inhaled. That’s why, after spraying with surfactant and herbicide, keep all animals away from the area where you applied the solution. The surfactant and herbicide no longer present a risk after drying.


Can surfactants for herbicides be used near water?

No, surfactants for herbicides should not be used near water sources like lakes, rivers, or streams.

Some synthetic herbicide surfactants can contaminate water sources, which can lead to harm to aquatic organisms and ecosystems.


Does surfactant for herbicides kill grass?

Surfactant for herbicides itself does not kill the grass. Even when added to the herbicide, as long as instructions are followed, herbicide surfactant does not affect the grass.


What happens if you do not use surfactant for herbicides?

If you do not use herbicide surfactant, then the herbicide may not adhere to the weed surface.

This will make the herbicide less effective, especially on weeds with glossy and waxy leaves. The herbicide will drip off the glossy surface and will no longer be absorbed by the weed. Thus, spraying herbicide without surfactant will not kill the weeds.


In conclusion, a surfactant for herbicides plays a role in improving the efficacy and overall performance in farming activities or personal use in your own garden. By improving the spread, adhesion, and penetration of the herbicide, surfactants help farmers achieve better weed control and contribute to higher crop yields.

As research continues to advance, we can expect to witness the development of even more efficient and eco-friendly surfactants for herbicides, paving the way for sustainable agriculture and food security.

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 ...

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