Paraquat (Porson) is a widely used herbicide in agriculture, particularly for controlling weeds before and after planting in field crops such as corn, soybeans, rice, and other economic plants. It is commonly applied to destroy weeds prior to seeding or harvesting, facilitating easier and faster crop collection.

Paraquat acts rapidly, destroying the foliage of weeds immediately after spraying, and degrades quickly upon contact with soil, preventing accumulation in soil or plants. This makes it suitable for non-persistent weed control when used at appropriate rates. However, paraquat is highly toxic to humans and animals; even minimal contact or ingestion can be fatal, leading to strict regulations and classification as a highly hazardous substance in many countries.