Which situation would require careful calculation of pesticide amounts to avoid over-application?

Applying during water stratification requires careful calculation of pesticide amounts to avoid over-application because water stratification can significantly affect how pesticides disperse and concentrate in aquatic environments. In stratified water, different layers may have varying temperatures, densities, and chemical compositions, which can change the effectiveness and potential toxicity of the pesticide. If pesticide is over-applied in such a situation, it could lead to higher concentrations than intended, resulting in environmental harm, particularly to aquatic life that might be more sensitive to elevated levels of pollutants.

In contrast, spraying in calm weather typically helps ensure that the pesticide is applied evenly and reduces the chances of drift, while using standard equipment generally does not pose risks regarding the amount of pesticide used as these tools often have calibration systems designed to provide the appropriate doses. Applying in a heavily vegetated area could present certain challenges related to penetration and coverage, but it wouldn't inherently necessitate the same level of caution regarding over-application as would the complexity of stratified water layers.