Understanding Adjuvants and Surfactants

Adjuvants are an import component of crop protection products. Some crop protection products require adjuvants as a separate addition and other products have them built into the formulation.

Some adjuvants are product specific, for example CHEM SPRAY® CROP OIL CONCENTRATE is designed to work exclusively with AURORA HERBICIDE products.

There are two types of adjuvant classes:

• Activators- surfactants and crop oil concentrates
• Utility Modifiers - drift reducers, pH modifiers, water conditioner, anti-foamers, compatibility agents

ACTIVATOR ADJUVANTS

• Commonly used to enhance post emergence herbicide performance
• Can increase herbicide activity, herbicide absorption into plant tissue, and rainfast period can also decrease photodegradation of the herbicide
• Can also impact the level of crop tolerance to the herbicide or the combination with its tank-mix partners
• Can alter the physical characteristics of the spray solution
• May include surfactants, crop oil concentrates, nitrogen fertilizers, spreader-stickers, wetting agents, and penetrants
  

Activator Adjuvant Subgroup 1

Surfactants

• Primarily reduce the surface tension between the spray droplet and the leaf surface to that of an oil or solvent, which spreads more readily than water on plant surfaces
• Allow more intimate contact between the spray droplet and the plant surface. This helps overcome the barriers that impede movement of the product from the leaf surface to the cell interior.
• Any substance that brings a pesticide into closer contact with the leaf surface has the potential to aid absorption (Figure 2).
• Includes nonionic, anionic, cationic, and organosilicones
• Required with certain post emergent herbicides and is contingent on the herbicide it is used with.
  

Figure 1. Effect of a surfactant on the spread and penetration of spray solutions across and through the leaf surface.

Types of Surfactants

Surfactants are classified as nonionic, anionic, or cationic.

• Nonionic surfactants have no electrical charge and are generally compatible with most pesticides. Nonionic surfactants are most commonly used because of their universal fit.
• An anionic surfactant possesses a negatively charged functional group and is most often used with acids or salts. Anionic surfactants are more specialized and sometimes used as dispersants or compatibility agents.
• Cationic surfactants are used less frequently, but one group (ethoxylated fatty amines) has sometimes been used with glyphosate.

Activator Adjuvant Sub-group 2

Crop Oil Concentrate (COC) And Vegetable Oil Concentrates

• Contain petroleum or vegetable-based oils plus some nonionic surfactants as a blend
• Increases herbicide penetration and reduces surface tension of the spray solution.
• Most frequently used with post emergent grass herbicides, however in recent years surfactants have been built into different formulations.
  - Axial® (with built in adjuvant)
  - Horizon® NG
• These tend to be somewhat more aggressive for uptake of the herbicide, and may increase risk of crop response
• Label guidelines should always be consulted before use.

Activator Adjuvant Sub-group 3

AMS

• Spray water quality can influence the performance of some pesticides. These characteristics include pH, water hardness and the presence of bicarbonates which may antagonize some herbicides.
• AMS (Ammonium sulfate) can reduce problems with hard water by preventing cations from inhibiting herbicide activity.
• It can also help some herbicides cross plant cell membranes, resulting in improved performance. (i.e. weak acid-type herbicides such as Refine, Infinity, etc).
• Generally used in combination with surfactants or crop oil concentrates
• Most common with Group 1 graminicides and amine formulations or with very low rates of glyphosate.
  

SELECTING ADJUVANTS

• Adjuvant use should be primarily based on product label recommendations
• Adjuvant use may not provide a benefit unless recommended or there are specific environmental conditions or label requirements.
  - Can impact herbicide or tank-mix efficacy
  - Can adversely impact crop tolerance increasing risk of injury
  - Can impact the product mixing, spray ability and potential for flocculation
  - Can impact tank-cleanout
• If you don’t know, don’t go with it.
• Talk to your AgraCity sales rep or agronomist if you are not sure.

WHAT ABOUT ADDING MICRONUTRIENTS?

• Numerous companies are recommending foliar nutrients added to spray mixtures based solely on compatibility tests.
  - Don’t account for efficacy, crop tolerance or adverse affects.
• AgraCity cannot support mixes that have not been evaluated, as it is impossible to test all potential mixes.
  - Potential for Adverse Effects
  - Potential for mixing, filling and spray- ability issues in commercial sprayers
  - Sediments, residue or films over multiple tanks that can lead to difficulty in tank cleanout.
• AgraCity cannot assume any risk or liability with growers who use foliar nutrient mixtures unless they have been tested.
• Utilize the JAR TEST. Not sure what the JAR TEST is? Click on the link below to find out how to use the JAR TEST to determine tank mix compatibility. Sprayer Loading and the Jar Test – Sprayers 101
  

ADJUVANTS AND SURFACTANT – SUMMARY

The need for an adjuvant is based on product chemistry and requirements:

• Most pre-seed products do not require adjuvant if mixed with glyphosate
• Group 2 products such as HIMALAYA HERBICIDE or MPOWER® RX HERBICIDE normally require non-ionic surfactant such as ASTRAL® ADJUVANT, AgSurf®, or Agral® 90 if used alone.
• SAMURAI® HERBICIDE and NINJA® HERBICIDE group 2 pulse products requires the use of ASSASSIN® II ADJUVANT or Merge®.
• Graminicide products usually require adjuvants, some are now built in.
• Broadleaf products containing 2,4-D or MPCA do not need additional surfactants and can act as a surfactant.
• Addition of non-labeled products can result in reduced product performance, crop injury, tank mix issues, or tank cleanout problems.

We have a complete lineup of adjuvants for every acre on your farm:
ASTRAL ADJUVANT: same active as Syngenta’s Agral® 90. For use as needed with BATTLEFRONT® HERBICIDE, CLONE® HERBICIDE, DESTROYER® 540 GLYPHOSATE HERBICIDE, DISRUPTOR® 540 GLYPHOSATE HERBICIDE, FOXXY® CRX II HERBICIDE, FOXXY PRO II HERBICIDE, FOXXY RCK II HERBICIDE, HIMALAYA® HERBICIDE, KAMIKAZE® HERBICIDE, MPOWER® EXTRA HERBICIDE, MPOWER® RX HERBICIDE, and REVENGE® HERBICIDE.

ASSASSIN® II ADJUVANT: same active as BASF’s Merge®. For use as needed with ANACONDA® HERBICIDE, BOA® IQ HERBICIDE, BOA PRO HERBICIDE, NINJA® HERBICIDE, NINJA MASTER HERBICIDE, QUIZ® HERBICIDE, SAMURAI® HERBICIDE and SAMURAI MASTER HERBICIDE.

EMPIRE II ADJUVANT: same active as UPL’s Amigo®, for use only with INDEPENDENCE® HERBICIDE.

NEED ASSISTANCE WITH ADJUVANTS? Call us at 1-844-269-3276 and press “3” to speak to an experienced agronomist.

ASSASSIN®, ASTRAL®, BATTLEFRONT®, BOA®, CLONE®, DESTROYER®, DISRUPTOR®, EMPIRE®, FOXXY®, HIMALAYA®, INDEPENDENCE®, KAMIKAZE®, MPOWER®, NINJA®, QUIZ®, SAMURAI® and REVENGE® are trademarks of AgraCity Crop & Nutrition Ltd. or its affiliates. All other products mentioned are trademarks of their respective holders.