Why is it important to avoid using esters in high temperatures?

Avoiding the use of esters in high temperatures is crucial because they have a tendency to volatilize or vaporize more readily in warm conditions. This characteristic can lead to vapor drift, where the chemicals become airborne and unintentionally move to non-target areas, potentially injuring desirable plants nearby. This is especially concerning in situations where sensitive crops or ornamentals are planted close to treated areas.

In contrast, the other options do not correctly address the primary concern with using esters in warmer conditions. For example, while cold weather may affect the effectiveness of other herbicides, esters specifically present a greater risk related to vapor drift in high temperatures rather than reduced effectiveness in colder conditions. Additionally, esters do not require excessive water for absorption, nor do they promote rapid weed germination, which further clarifies why option B is the accurate choice.