Fensulfothion is an organophosphate insecticide/nematicide. Fensulfothion is highly toxic to man and other non-target terrestrial and aquatic organisms from acute oral and dermal routes of exposure. Fensulfothion is registered for use as preplant or at-planting soil application to tobacco and various fruits and vegetables. Postplant topical applications are permitted in addition to the at-planting application on corn, peanuts, and rutabagas. Topical application is also permitted on commercial and ornamental turf. Fensulfothion is an organophosphate insecticide/nematicide that kills primarily by contact action, but also provides some systemic control of insects attacking the foliage of treated plants. The mode of action is by phosphorylating the acetylcholinesterase enzyme of tissues, allowing accumulation of acetylcholine at nerve junctions, with subsequent blocking effects upon the central nervous system.