Adjuvants in Pesticides
One type of adjuvant, surfactants, are used to help droplets of an herbicide stick and spread on a leaf surface.
Adjuvants are added to products to help the pesticide do its job and stay on target. They may be in a formulated product when it's purchased. Or, they may be added to a mixture before it is applied (tank-mixed).
Many adjuvants are surfactants. Surfactants are also called "surface acting agents" or wetter-spreaders. They flatten and spread droplets so that a product can penetrate a leaf.
An adjuvant may be in a product for many reasons, including to:
- Reduce off-site movement (drift) of a product
- Help an herbicide stick to a plant leaf
- Allow a product to penetrate a waxy leaf
- Reduce foaming during mixing
- Control acidity in a tank mixture
Factors to consider:
- Most adjuvants are not required to be listed on pesticide product labels. If included in the mixture, they are considered “other/inert ingredients.”
- Mixtures of ingredients can behave differently in the environment or the body compared to an ingredient alone. For example, some surfactants can increase skin absorption of a product. Or, a mixture may break down faster in soils compared to an ingredient on its own.
- Adjuvant products (tank-mixed) are not registered with the federal EPA. However, some states require registration. Consider contacting your state pesticide regulatory agency for information.
- Always read product label directions. It may state which adjuvants should or can be used with the product.
- A local expert may be able to provide guidance for adjuvant selection.
- A manufacturer may be able to answer questions about tank-mixed adjuvant products.
If you have questions about this, or any pesticide-related topic, please call NPIC at 800-858-7378 (8:00am - 12:00pm PST), or email us at email@example.com.
Last updated July 12, 2021