What do the terms preemergence, postemergence, and selective describe?

The terms preemergence, postemergence, and selective specifically describe the characteristics and application timing of herbicides.

Preemergence herbicides are applied before the target plants' seeds germinate, preventing them from growing. These products create a chemical barrier in the soil that stops weeds before they can emerge.

Postemergence herbicides, on the other hand, are applied after the weeds have already emerged, targeting the plants directly to kill them while they are growing.

Selective herbicides are designed to target specific types of plants (often weeds) without harming desirable species, such as grasses or broadleaf plants. This selectivity is crucial for maintaining the health and aesthetics of lawns and gardens.

These terms highlight important functional aspects of herbicides, which distinguishes them from fertilizers, which are intended for plant nutrition, and insecticides, which target pests rather than unwanted plants.