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Adjuvants and Surfactants for Better Weed Control

Mon, Apr 13th, 2026, created by Debalina Saha

Herbicides play a vital role in protecting crops but simply applying them may not always give the best results. Sometimes, additional products called adjuvants are added to herbicide mixtures to improve their performance. Understanding how adjuvants — especially surfactants — work can help growers make more effective, safer, and economical herbicide applications. Adjuvants are chemical substances added to herbicide formulations or spray tanks to improve how the herbicide works. They do not have any direct pest control activity themselves, but they can:

  • Improve effectiveness of herbicides
  • Make it easier to mix with other products
  • Change the way the spray behaves on plants
  • Increase safety or reduce unintended effects

There are many types of adjuvants available, each designed for a specific purpose. The various types include defoamers, compatibility agents, drift control agents, buffers or pH modifiers, extenders and stickers, wetting agents, spreader adjuvants, safeners, emulsifiers, penetrants, thickeners. Many growers use the terms adjuvant and surfactant interchangeably, but they are not the same. All surfactants are adjuvants, but not all adjuvants are surfactants. Surfactants are a special category of adjuvants designed to change how spray droplets interact with plant surfaces. Surfactant’s main functions include:

  • Improve spreading of spray droplets
  • Enhancing wetting of leaves and plant surfaces
  •  Promoting better absorption of pesticides 

In simple terms, surfactants help the herbicide "stick” and spread more evenly across the treated surface, making it more effective.

Adjuvants and surfactants can significantly enhance herbicide performance, but only when used correctly. Not all adjuvants are needed for every application. Always read the label instructions, as it may recommend specific adjuvants or prohibit others. The label will also help you understand the role of each additive and then choose products that suit your specific growing needs. When in doubt, seeking advice from extension experts, product manufacturers, or trusted agronomy professionals as using the right adjuvant can improve herbicide performance, save money, and protect crops. 


About the Author:

Debalina Saha

Assistant Professor, Michigan State University

Debalina Saha is an Assistant Professor of ornamental weed management in the Department of Horticulture at Michigan State University. She has an appointment in research, teaching, and extension. Debalina provides statewide weed identification and management recommendations for ornamental plant production in greenhouses, nurseries, landscapes, and Christmas tree production. The primary goal of her research program is to improve upon current weed control practices and develop new effective methods of weed control using an integrated approach that involves both chemical and non-chemical strategies.

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