What type of pesticide is most likely to be used for long-lasting weed control?

Residual pesticides are specifically designed to remain active in the environment for extended periods, providing long-lasting control of targeted pests, including weeds. Unlike contact herbicides, which only affect the area they directly come into contact with, residual pesticides can persist in the soil or on plant surfaces to control weeds that germinate or emerge later. This prolonged action offers an advantage in preventing weed regrowth over time.

Other types of pesticides serve different purposes. For example, contact herbicides are effective only when they touch the plant or weed, but they don't provide lasting effects once they degrade. Systemic herbicides, while they do move throughout the plant to kill it from within, may not have residual activity in the soil for controlling later emerging weeds. Fumigants primarily target soil-borne pests and pathogens through vaporization and are not used for long-term weed control.