Adjuvants 101: Understanding the “Extras” in Your Tank

Apr 01, 2026

Share this post on:

When it’s time to apply an herbicide, or maybe a pesticide, insecticide or fungicide, you want to ensure you’re getting the most out of every droplet that leaves the sprayer.

Are you including an adjuvant in your tank mix? How do you know if you should? This post outlines what adjuvants are, when to use them, and how to choose which one for your specific use case.

Watch Video: Mastering Adjuvants

Dr. Mitch Roth, FBN® regional agronomist, explains how to maximize the effectiveness of your crop protection with adjuvants in this webinar.

What Is an Adjuvant?

An agricultural adjuvant is a non-pesticide product added to a spray tank mix that enhances the performance of the spray solution. Adjuvants often improve spray mix characteristics – such as spreading, penetration or droplet size – or reduce any potential application problems from the spray mix itself, thus increasing effectiveness. Examples of adjuvants include surfactants, oils, buffers, and defoaming agents.

Spray adjuvants can be categorized into two groups:

Activator adjuvants
Utility adjuvants

Activator Adjuvants

Activator adjuvants improve the action of a pesticide product by encouraging absorption and efficacy. This category of adjuvants includes:

Surfactants
Oils
Nitrogen-based fertilizers

Surfactants

Surfactants change the surface tension of a spray droplet. They make the area of pesticide coverage larger, increasing exposure to the chemical. These are useful when applying a pesticide to a plant with waxy or hairy leaves.

Some commonly used surfactants include:

Nonionic Surfactants: Compatible with most pesticides - Help pesticide sprays penetrate plant cuticles - Are recommended for most pesticides that require a surfactant
Organo-silicone Surfactants: Reduce surface tension, increase spreadability and improve rainfastness

Oils

Crop oils promote the penetration of a pesticide spray either through a plant's waxy cuticle. Two commonly used variations are:

Crop oil concentrates (COCs) have the penetration of an oil with the spread of a surfactant. COCs are often used with post-emergence herbicides.
Vegetable oil concentrates (VOCs), in many cases, have gone through a process called esterification, which results in a methylated seed oil (MSO). MSOs work similarly to COCs to increase penetration of the pesticide.

Nitrogen-Based Fertilizers

Adding ammonium sulfate (AMS) or urea-ammonium nitrate (UAN) to a spray mix has been shown to increase the efficacy of some herbicides. Many times, these are available in easier-to-mix liquid forms, which provide more consistent results.

Utility Adjuvants

Utility adjuvants, also referred to as special purpose adjuvants, correct conditions that can negatively affect the spray solution or application to help optimize pesticide performance. This group of adjuvants includes:

Buffers: Most pesticides perform best in slightly acidic spray water with a pH of 4.0 to 6.5. Those in solutions above pH 7.0 are at greater risk of breaking down. Buffers lower the pH of spray water and help stabilize it at a constant level.
Conditioning Agents: Hard water minerals can bind with active ingredients in some pesticides, decreasing pesticide performance. Water conditioners neutralize these minerals and protect the spray mix from this problem. Many conditioners will also include a buffer.
Defoaming Agents: Defoaming agents reduce the foam created in spray tanks, often caused by pesticides that become foamy when interacting with a surfactant or spray tank agitation system.
Stickers: Stickers increase the ability of particles to stick to a surface, decreasing the amount of pesticide that washes off during irrigation or rain. They can also reduce pesticide evaporation and slow degradation of pesticides by UV rays.
Drift Control Agents: Drift control agents improve the placement of pesticide sprays by increasing droplet size, a priority near sensitive sites or when conditions require increased caution.
Foam Makers: When used with special equipment, these adjuvants produce foam to mark where a product was applied, helping avoid missed or overlapping areas.
Tank Cleaners: Tank cleaners work with water and oil-soluble pesticides and are often recommended by pesticide labels.

How Do You Know Which Adjuvant to Include in Your Tank Mix?

Most pesticide labels will include a section to help you decide what type of adjuvants will help you get the most out of your application. These often utilize language such as “required,” recommended,” or “can be used” to help you understand which adjuvants are essential to your mix and which ones are optional.

Before using any adjuvant, always read and follow the accompanying pesticide or other product label. Not all adjuvants are labeled for use in all states, and many adjuvants have crop specific recommendations as well. Violating these instructions is an illegal use of the pesticide and can result in crop damage or poor performance.

How to Select the Right Activator Adjuvant: Choosing Between NIS vs. COC vs. MSO

Choosing the right activator adjuvant is the difference between a clean field and a "re-spray." While they all aim to improve chemical performance, they work in very different ways.

1. Non-Ionic Surfactants (NIS)

What it is: A surfactant that lacks an electrical charge. It is the most versatile and "gentle" adjuvant.
Why it’s helpful: It reduces the surface tension of the spray droplet, allowing it to "flatten" and cover more leaf surface area rather than bouncing off.
When to use it: Use NIS when the pesticide label requires it, specifically for most systemic herbicides and fungicides. It is the best choice when crop safety is a concern, as it is less likely to burn the crop than oil-based products.

2. Crop Oil Concentrates (COC)

What it is: An oil-based adjuvant (usually petroleum-derived) mixed with a small amount of surfactant (usually 15-20%).
Why it’s helpful: COCs help the chemical penetrate the waxy cuticle of the leaf. They are more "aggressive" than NIS and help reduce evaporation in hot, dry conditions.
When to use it: Use COC for post-emergence herbicides when you are targeting larger weeds or when weather conditions are harsh (low humidity). It is commonly used with grass herbicides.

3. Methylated Seed Oils (MSO)

What it is: A chemically modified seed oil (like soybean or canola) that is significantly more powerful at dissolving leaf waxes than standard COCs.
Why it’s helpful: MSO is the most aggressive penetrant available. It allows the active ingredient to "move" through the thickest leaf barriers, ensuring the chemical reaches the plant's vascular system.
When to use it: Use MSO for "tough-to-kill" broadleaf weeds like Waterhemp, Palmer Amaranth, or Kochia. Note: Because it is so effective at penetration, it carries a higher risk of crop injury (phytotoxicity) if used under the wrong conditions.

How to Select the Right Utility Adjuvant

Selecting the right utility adjuvant is about identifying the "invisible" obstacles between your tank and the weed. While activator adjuvants help the chemical work once it hits the leaf, utility adjuvants ensure the chemical actually gets there in a stable, effective form.

To choose the right one, evaluate your application based on these three environmental factors:

1. Test Your Water Source

The water in your tank makes up over 90% of your spray volume. If you have "hard water" (high in calcium, magnesium, or iron), these minerals can bind to your herbicide molecules, rendering them useless.

The Fix: Use a Water Conditioner or Ammonium Sulfate (AMS) to sequester those minerals before you add your chemicals.

2. Check the Weather and "Drift Risk"

If you are spraying near sensitive crops or in sub-optimal wind conditions, your biggest risk is "fines"—tiny droplets that drift off-target.

The Fix: Add a drift reduction agent (DRA) to manage droplet size or a deposition aid to ensure the spray reaches deep into the crop canopy.

3. Monitor Tank Stability

Mixing multiple products (herbicides, insecticides, and foliar fertilizers) creates a complex chemical soup. If you notice "slugging," clumping, or excessive foaming, your application uniformity is at risk.

The Fix: Use a compatibility agent to keep the mixture fluid or a defoamer to prevent air entrapment and pump cavitation. Always perform a jar test before mixing a full load.

Activator Adjuvants at a Glance

While utility adjuvants manage the journey from the tank to the leaf, activator adjuvants are the "door openers" that break down physical barriers to ensure the active ingredient successfully penetrates the plant's surface.

Adjuvant Type	Primary Function	Best For...	Key Performance Factor
Non-Ionic Surfactant (NIS)	Spreading & Wetting	General herbicides, fungicides	Lowers surface tension; most common choice.
Crop Oil Conc. (COC)	Penetration & Retention	Large weeds; dry weather	High oil content; improves leaf contact.
Methylated Seed Oil (MSO)	Maximum Penetration	Toughest weeds (e.g., Pigweed)	Chemically modified to dissolve thick leaf wax.
Organosilicone	"Super-Spreading"	Dense canopies; high-speed spraying	Drastic reduction in droplet surface tension.

Utility Adjuvants at a Glance

While activators help the chemical get into the plant, utility adjuvants ensure the chemical survives the tank and the air on the way to the leaf.

If You Are Dealing with...	Use This Adjuvant...	Why?
Hard Water / High pH	Water Conditioner / AMS	Neutralizes minerals that bind to and deactivate chemicals.
Wind / Drift Concerns	Drift Reduction Agent (DRA)	Increases droplet size to reduce "fines" that float away.
Foaming in the Tank	Anti-Foamer / Defoamer	Prevents air entrapment and messy tank overflows.
Waxy or Hairy Leaves	Sticker or MSO	Ensures the chemical stays "stuck" to the plant surface.
Poor Mixing (Clogging)	Compatibility Agent	Prevents chemicals from clumping into "cottage cheese."

Optimize Your Application with Adjuvants from FBN®

Double down on savings and convenience when you shop for adjuvants and other key ag inputs on FBN. Using FBN’s convenient online store, simply search for the adjuvants you need and immediately see product availability, pricing, labels and other details.

Plus, you’ll get direct-to-farm delivery in three days or less.

Recommended Adjuvants from FBN

Farmers First™ Even™ L Pro is an optimized premix of drift management agents, deposition aids, AMS and surfactant. Designed to enhance the performance and activity of pesticide sprays by reducing tie-up of herbicides in hard water, it improves spray application coverage and minimizes spray drift.
Farmers First™ FieldGrip™ DRA is a high-concentrate emulsifiable deposition aid and drift management adjuvant.
Farmers First™ IN-Plant™ is a crop oil concentrate adjuvant containing paraffinic oil, emulsifiers and surfactants.

Related Resources

© 2014 - 2026 Farmer's Business Network, Inc. All rights Reserved. The sprout logo, “Farmers Business Network”, “FBN”, “FBN Direct” are trademarks or registered trademarks of Farmer's Business Network, Inc.

FBN Direct products and services and other products distributed by FBN Direct are offered by FBN Inputs, LLC and are available only in states where FBN Inputs, LLC is licensed and where those products are registered for sale or use, if applicable. If applicable, please check with your local extension service to ensure registration status. Nothing contained on this page, including the prices listed should be construed as an offer for sale, or a sale of products. All products and prices are subject to change at any time and without notice and excludes CA mills tax and MN ACRRA fees. Terms and conditions apply.

ALWAYS READ AND FOLLOW LABEL DIRECTIONS. It is a violation of federal and state law to use any pesticide product other than in accordance with its label. The distribution, sale and use of an unregistered pesticide is a violation of federal and/or state law and is strictly prohibited. We do not guarantee the accuracy of any information provided on this page or which is provided by us in any form. It is your responsibility to confirm prior to purchase and use that a product is labeled for your specific purposes, including, but not limited to, your target crop or pest and its compatibility with other products in a tank mix and that the usage of a product is otherwise consistent with federal, state and local laws. We reserve the right to restrict sales on a geographic basis in our sole discretion. You must have a valid applicator license to use restricted use pesticides. Please consult your state department of agriculture for complete rules and regulations on the use of restricted use pesticides, as some products require specific record-keeping requirements.

All product recommendations and other information provided is for informational purposes only. It is not intended to be a substitute for consulting the product label or for specific agronomic, business,or professional advice. Where specific advice is necessary or appropriate, consult with a qualified advisor. Neither Farmer's Business Network Inc. nor any of its affiliates makes any representations or warranties, express or implied, as to the accuracy or completeness of the statements or any information contained in the material and any liability therefore is expressly disclaimed.

FBN Network

Apr 01, 2026

Share this post on: