What should always be checked before applying a pesticide?

The correct choice emphasizes the importance of consulting the manufacturer's label prior to pesticide application. The manufacturer's label serves as a critical resource that provides essential information such as appropriate application rates, timing, and specific safety precautions that must be followed. This ensures that the pesticide is used effectively while minimizing risks to the environment, non-target organisms, and human health. By adhering to the guidelines on the label, applicators can achieve optimal results while maintaining compliance with legal requirements.

While checking the pH level of the soil, the size of the equipment, and the availability of organic alternatives may be relevant in certain scenarios, they are not universally applicable for every pesticide application. The manufacturer's label is a non-negotiable first step that directly impacts safe and effective pesticide use, making it the most critical aspect to check before proceeding with any application.