Which of the following is an example of a substance added to a pesticide to enhance its effectiveness?

The correct answer is an adjuvant or additive, as this term specifically refers to substances that are mixed with a pesticide to enhance its performance. Adjuvants can improve the pesticide's effectiveness by facilitating better spray coverage, increasing absorption into plants, helping to resist environmental degradation, or modifying its physical properties for easier application. This enhances the overall efficacy of the pesticide, leading to better pest control.

Fertilizers and herbicides serve different purposes in agricultural practice. Fertilizers provide nutrients to plants, and while they may indirectly affect the health of plants and their resistance to pests, they do not specifically enhance the effectiveness of a pesticide. Herbicides are a type of pesticide used to control weeds and, although they are related to the category of substances used in pest management, they do not function as adjuvants.

By understanding the essential role of adjuvants, you can appreciate their critical function in improving the application and performance of pesticides in your turf and ornamental management practices.