What Is An Adjuvant?

Adjuvants, (Spray Adjuvant, Sticker, or Agricultural Adjuvant) are a critical part of an integrated pest management (IPM) program. This article will outline the basis function of Adjuvants, and their benefits. We will then look at the different types of Adjuvants in more depth, and ensuring you select the right Adjuvant for the right purpose.

What is an Agricultural Spray Adjuvant?

Adjuvants are materials added to agrochemical products; Fungicides, Herbicides, and Insecticides, to enhance the efficacy of active ingredients in the product.

How they work:

Agricultural spray adjuvants are not themselves active in controlling or killing pests. Instead, these additives modify properties of the spray solution, improving the ability of the pesticide to penetrate, target or protect the target organism.

Benefits of using Adjuvants:

• Providing more efficient delivery of your agrochemicals.
• Reducing the quantity of agrochemicals you need to apply to your crop
• Extending the spectrum of effectiveness of your agrochemicals
• Replacing high-value or high-toxicity active ingredients with lower value surfactants

Which lead to:

• Better performance and therefore increased yields
• Less chemical environmental pressures
• Reduced costs
• Improved food safety due to lower residue levels

How they are applied:

In-can or Formulation Adjuvant - when an adjuvant is included in the crop protection product, and the farmer doesn’t need to use additional adjuvants. Check the label of your crop protection product to confirm.

Tank Mix or Spray Adjuvant - is when an Adjuvant is kept in a separate tank from the crop protection product and added when the spray solution is prepared.  The label on your crop protection product will state the type of adjuvant that should be used. Below we will go through the different types of Adjuvant in more depth.

Types Of Adjuvants:

This is where this blog gets more technical, as we look at the differentiate between the two main types of Adjuvant: Surfactant and Oil.

1.      Surfactant (Adjuvant)

The waxy surfaces of many insects, fungi, and plants make it difficult for most water-based spray solutions to penetrate their target. Why do water based spray solution struggle to penetrate waxy surfaces? The answer is surface tension. The molecules on the surface of a water droplet are held together with more force than those of the interior water molecules. This causes surface tension, which can prevent particles from going into the solution and getting wet.

How do Surfactant overcome Surface Tension?

Surfactants physically change the properties of the spray solution to overcome surface tension. They help improve the pesticide’s ability to emulsify, disperse, spread, and stick by reducing surface tension.

Classification of Surfactants:

They are classified by the way they ionize, or split apart, into electronically charged molecules called ions. These ions are made up of a water-loving head (hydrophilic) and an oil-loving tail (lipophilic), which will have either a neutral, positive, or negative charge. This enables the surfactant to bond with the spray droplets, allowing the spray droplet to stick and spread out over the leaf surface. Only use the type of surfactant listed on the label. Below are the 3 main types.

1. Non-ionic surfactants (neutral/no charge): most commonly used type of surfactant and typically recommended for use with most registered pesticides -- Help with spray droplet retention, spreading, and penetration of leaf surfaces -- Composed of alcohols and/or fatty acids and are compatible with most pesticides -- Pesticidal activity can be quite different than if an anionic or cationic surfactant was added
2. Anionic surfactants (negative charge)
3. Cationic surfactants (positive charge)

The last two surfactants are not generally used with pesticides.

2.     Oil (Adjuvant)

The three types of oil-based adjuvants include crop oils, crop oil concentrates, and methylated seed oils. They increase the penetration of spray droplets and help reduce surface tension.

1. Crop oils are generally made of 95 to 98 percent paraffin or naphtha-based petroleum oil and 1 to 2 percent surfactant/emulsifier. Crop oils promote the penetration of a pesticide spray either through a plant’s waxy cuticle or an insect’s tough, chitinous shell. Traditional crop oils are more commonly used for insect and disease control and rarely with herbicides.
2. Crop oil concentrates (COCs) are made up of 80 to 85 percent emulsifiable petroleum-based oil and 15 to 20 percent non-ionic surfactant. Crop oil concentrates have the penetration properties of oil and the spreading properties of a surfactant. They also help increase the water solubility of some of the less-soluble herbicides.
3. Methylated seed oils (MSOs) are made up of 80 to 85 percent crop-derived seed oil (cotton, linseed, soybean, or sunflower oil) and 15 to 20 percent non-ionic surfactant. To improve their performance, many MSOs have undergone a process called esterification, which changes a seed oil’s characteristics, so it is attracted to and can be dissolved in water. MSOs work in the same manner as traditional crop oil concentrates by increasing the pesticide’s ability to penetrate the target pest.

How to Choose the Right Adjuvant

The purpose on an adjuvant is to improve a pesticide’s performance and/or change a pesticide’s characteristics to minimize problems when mixing and applying. Why making a selection remember the following:

• ALWAYS READ THE LABEL!
• Use only adjuvants manufactured and marketed for agricultural or horticultural uses.
• Be aware that some adjuvants may be more toxic than the pesticide. Choose the least toxic adjuvant that meets your needs.
• Pesticide labels seldom mention specific brands of adjuvants but rather the general type of adjuvant, such as non-ionic surfactant or crop oil.
• Miracle adjuvants do not exist. Ignore claims such as “keeps spray equipment clean" or “causes better root penetration."
• Always buy high-quality, name-brand products from a reputable dealer.

Spray adjuvants can play a major role in the safe and effective use of pesticides when used as recommended on the label. Although a single adjuvant may perform more than one function, no single product can improve the performance for all pesticides or solve every problem. The critical part is making sure you read the label and use a suitable adjuvant to ensure the best performance for your chosen agrochemical.

Get in touch today to understand more about adjuvants and how best they can enhance your pest management program.

Phone: +233 24 529 7047

Email: info@demeterafrica.com