propanil

Propanil is an herbicide used primarily in rice production to control annual grasses such as barnyardgrass and some broadleaf weeds. It is N-(3,4-dichlorophenyl)propionamide, a chloroanilide-type compound employed in several formulations for weed management in flooded rice fields.

Propanil is typically applied postemergence as an emulsifiable concentrate (EC) or wettable powder (WP), and is often tank-mixed with other herbicides or adjuvants to broaden control. It is absorbed mainly through foliage and can be translocated to growing points, contributing to its selective activity in rice.

Mode of action: Propanil acts as a photosystem II inhibitor, binding to the plastoquinone-binding site in chloroplasts and interrupting electron transport. This disruption leads to light-dependent injury and necrosis in susceptible plants. The crop, rice, shows tolerance due to specific metabolic or physiological factors, enabling selective control.

Environmental fate and safety: Propanil degrades in soil via microbial action and hydrolysis, with photolysis also contributing to dissipation. The principal degradation product is 3,4-dichloroaniline, which can be more toxic. In usage, propanil has moderate acute toxicity to mammals and is toxic to aquatic organisms; labels require precautions to avoid drift and water contamination, and protective equipment for handlers. Regulatory status varies by country, but propanil is registered under pesticide licensing schemes with restrictions intended to protect water resources.