What term describes the application of an herbicide after the weed has started to grow?

The term that describes the application of an herbicide after the weed has started to grow is "postemergent." This type of herbicide is specifically formulated to target weeds that have already emerged above the soil surface. Postemergent herbicides work by being absorbed by the leaves of the plants, which allows them to kill the existing weeds in their active growth stage.

In contrast, preemergent herbicides are applied before weeds germinate, preventing their emergence. Translocated herbicides refer to the movement of the herbicide within the plant after it has been absorbed, but this term does not specify when the application occurs relative to weed growth. Residual herbicides are designed to remain in the soil and control weeds that may emerge later, but they are generally not used after the weeds have already begun to grow. Understanding these distinctions is crucial for effective weed management strategies in various agricultural and industrial settings.