When should preplant herbicides be applied?

Preplant herbicides are specifically designed to be applied before the crop is planted. This timing is crucial because their primary function is to control weed populations in the soil prior to the establishment of the desired crop. Applying these herbicides ahead of planting allows for effective weed suppression, reducing competition for resources such as water, nutrients, and light.

Applying herbicides after the crop has emerged or once weeds are already present does not utilize the preplant herbicide's benefits effectively, as their intended purpose is to prevent weed growth before it starts. Applying herbicides at the moment of planting may not give them sufficient time to act on potential weeds already present in the soil, and would not allow for the desired weed control that preplant herbicides are designed to provide. Therefore, timing their application before planting aligns with best practices in weed management in forestry and agricultural settings.