What is a Surfactant and When to Use One

What is a Surfactant and When to Use One

What is a Surfactant and When to Use One

Oftentimes when homeowners or even professionals go to spray weeds with a liquid herbicide, the herbicide will roll off the ends of the weed’s leaves before getting a chance to soak into its system. This can make your herbicide applications ineffective, which in turn results in wasted time, money and effort.

Surfactants are commonly used in combination with most liquid herbicides to help the solution stick to the leaves or blades of the weed so that the chemicals can effectively soak into the plant’s system.

What is a surfactant?

A surfactant is often referred to as a wetting agent—it works as a sort of “buffer” for the herbicide chemical you are applying and breaks up the surface tension of the liquid. This allows for the chemicals in the herbicide to stick to the plant’s surface instead of rolling off and breaks down the plant’s resistance in absorbing the chemical that’s applied.

A surfactant will also break surface tension up in soil so that herbicides render effective. One of the most popular surfactants lawn care enthusiasts turn to is Southern Ag Surfactant, which Sod University discusses further down in this blog.

When should I use a surfactant?

First, it should be noted that surfactants are not designed to be used alone—they must be used in combination with other liquid products like fungicides, fertilizers, insecticides or most frequently, with herbicides for weed control. You can often refer to your control product’s label to see if it can be used with a surfactant just to be safe. When you choose to treat your lawn weeds with a surfactant, you should:

  1. Identify the type of weed your are experiencing,
  2. Purchase a selective herbicide that is labeled to treat the weed you want to control without harming your lawn and
  3. Purchase a surfactant that works in combination with the herbicide you decided to use.

Identifying the type of weed you are encountering is an important step in selecting an herbicide. Afterall, you’ll want a product that actually works to control the weed you see outside. A selective herbicide, in comparison to a non-selective, works to control the weeds it is labeled to kill. A non-selective herbicide on the other hand will kill every plant it comes in contact with—including your grass. An example of a non-selective herbicide would be a glyphosate product. You can still use a surfactant with both selective and non-selective herbicides, but be prepared for a non-selective herbicide to kill everything it touches.

As stated in #3 above, it is important to read product labels on both your surfactant and herbicide products thoroughly before any mixing or applications take place. You may even find an herbicide that already has a surfactant included in its mixture.

Why should I use Southern Ag Surfactant?

It is important to read the product label for the surfactant you selected so that you know which of the herbicide active ingredients your surfactant will work with. Southern Ag Surfactant particularly works well with herbicide chemicals like Trimec, Atrazine, Brush Killer and 2, 4-D Amine. Be sure to also consult your herbicide’s product label to see which active ingredient it uses.

Southern Ag Surfactant serves to reduce surface tension of water to insure more uniform, increased coverage and penetration of any herbicide it is applied with. 80 percent of its makeup is a non-ionic surfactant while the other 20 percent is made up of pesticide adjuvant, which is broadly defined as any substance in an herbicide formulation or added to the spray tank to improve herbicidal activity or application characteristics.

How do I apply Southern Ag Surfactant?

Generally speaking, you should only need one teaspoon per gallon of Southern Ag Surfactant for most herbicides. Adding just a touch of a surfactant will increase the effectiveness of all your herbicides by breaking the surface tension of the herbicide and leaf surface.

When using Southern Ag Surfactant with a non-selective herbicide or an herbicide that uses MSMA, use one tablespoon per gallon of Southern Ag Surfactant. Refer to the product label below for more information.

Adding Southern Ag Surfactant to your herbicide mixture allows the herbicide of choice to stick around and sit on the leaf surface long enough to be absorbed by the weed. This increases the herbicide’s ability to penetrate into the weed and reduces the chances of the solution running off.

Overall, applying any surfactant should increase the herbicides effectiveness and therefore reduces the amount of herbicide you use to control weeds. This can result in actually saving money instead of recklessly spending it on more herbicides. Be sure to check out some of our herbicide products that are most popularly purchased with Southern Ag Surfactant like Tenacity Herbicide.


  • Coverage: Covers one to two acres when mixed properly.
  • Active Ingredient(s): Mesotrione 40%.
  • Ease of Use: Requires tank mixing and application with sprayer.
  • Best Used On/For: Difficult to remove outdoor weeds.

Southern Ag Surfactant 1 Pint

  • Coverage: One quart covers 3,700 sq. ft.
  • Active Ingredient(s): Atrazine 4%.
  • Ease of Use: Requires tank mixing and application with a sprayer.
  • Best Used On/For: Established St. Augustinegrass and centipedegrass.

SpeedZone Southern Herbicide

  • Coverage: One gallon covers between 71,000–171,000 sq. ft.
  • Active Ingredient(s): 2,4-D, 2-ethylhexyl ester 28.57%, Carfentrazone-ethyl 0.62%, Dicamba 1.71% and Mecoprop-P 5.88%.
  • Ease of Use: Requires tank mixing and application with sprayer.
  • Best Used On/For: Broadleaf control in established grasses. Product demonstrates superior cool season performance.

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