An adjuvant is a chemical that can be added to a pesticide spray mixture to enhance and modify the physical properties of the pesticide for the spray mix. An adjuvant is a specialized chemical that must be matched to a particular pesticide, the problem, and environmental conditions to ensure that they enhance and do not detract from the effectiveness of the pesticide.
Based on their intended use or type of action, adjuvants can be divided into three broad categories: activators, spray modifiers, or utility modifiers.
Derived from the words surface-acting agents, a surfactant is a compound that improves the emulsifying, dispersing, spreading, wetting, or other surface-modifying properties of liquids. Whereas surfactants make up a large class of adjuvants, not all adjuvants are surfactants.