Which substance is used to enhance the effectiveness of a pesticide?

An adjuvant is a substance that is added to a pesticide formulation to enhance its effectiveness. It can help improve the pesticide's capabilities in several ways, such as increasing its absorption, improving its distribution on the target area, or enhancing its uptake by plants or pests. Adjuvants can also help the pesticide to overcome environmental factors that may limit its performance, such as rain or drought.

In contrast, fertilizer is primarily used to provide essential nutrients to plants and does not enhance the pesticide's efficacy directly. Water, while necessary for diluting and applying pesticides, is not an enhancer but rather a carrier. Soil serves as the medium in which plants grow and may interact with pesticides, but it does not serve to enhance their performance in the application process.