Adjuvants and Surfactants

• Anionic surfactants – have a negative charge and in aqueous solutions they form anions.
  • Anionic surfactants enhance foaming and other spreading properties of a liquid and are commonly used in shampoo.
  • If anionic surfactants are used with herbicides, the spray mixture can produce excessive amounts of foam that can negatively affect spray delivery and the control of plants.
• Ampholytic (amphoteric) surfactants –have both positive and negative charge and in aqueous solutions they are capable of forming anions and cations, depending on the pH of the solution.
  • Amphoteric surfactants are used rarely. When used, the amphoteric surfactant must match the properties of the herbicide formulation.
• Nonionic surfactants – produce little or no ionization (no electrical charge) in water.
  • Nonionic surfactants do not have a charge in solution and are the most commonly used surfactants with herbicides.

Why are nonionic surfactants preferred for use with herbicides?

Nonionic surfactants are the most commonly used and preferred surfactant for application with many pesticides, including herbicides, growth regulators, defoliants, fungicides, and insecticides.

Features of nonionic surfactants

Nonionic surfactants:

• Are composed of alcohols and fatty acids.
• Have no electrical charge.
• Remain stable in cold water.
• Arecompatible with many herbicides.

Benefits of using nonionic surfactants with herbicides

Nonionic surfactants:

• Do not harm plants when used properly. However, application rate is critical because when they are applied at too high a rate injury to desired plants (non-targets) may occur.
• Reduce surface tension of the spray solution