What is the term for a substance added to a pesticide to improve its effectiveness or safety?

The term for a substance added to a pesticide to improve its effectiveness or safety is known as an adjuvant. Adjuvants serve various purposes, such as enhancing the pesticide's performance, increasing adherence to targeted surfaces, or improving the pesticide's ability to penetrate plant tissue. They can modify the physical or chemical properties of the pesticide formulation, making it more effective under specific conditions.

Active ingredients refer to the chemicals in the pesticide that are responsible for its intended effect, while adjuvants work in conjunction with these active ingredients to maximize efficiency. Surfactants and emulsifiers are specific types of adjuvants that can help reduce the surface tension of the liquid, allowing better spreading and wetting of the pesticide on the target surface or assisting in mixing oil and water components in a formulation. However, the broader term for any additive aimed at enhancing performance or safety is adjuvant.