Under what conditions should a pesticide application be postponed?

Postponing a pesticide application during high winds, heavy rains, or extreme temperatures is essential to ensure both effectiveness and safety. High winds can cause the pesticide to drift away from the target area, leading to reduced efficacy and potential harm to non-target species, including humans and beneficial insects. Heavy rains can wash away the pesticide before it has a chance to work, resulting in wasted chemicals and insufficient pest control. Extreme temperatures, whether too high or too low, can also affect how pesticides behave. For instance, high temperatures can increase evaporation rates, while cool temperatures might inhibit the chemical's effectiveness or delay its action.

Conditions such as the presence of visible pests, nighttime application, or dry fields may not necessarily warrant postponing an application. Visible pests indicate that action may be needed rather than postponing the application. Applying pesticides at night may sometimes be considered to avoid heat and sunlight; however, visibility issues can arise, making it difficult to monitor the application. Lastly, a dry field might not be an immediate reason to postpone unless it affects the absorption of the pesticide, but it could be applicable depending on the specific pesticide and context. Therefore, the environmental conditions highlighted in the correct answer are critical factors influencing the timing and efficacy of pesticide applications.