Systemic Activity and Phytotoxicity of Fluensulfone in Vegetable Transplants Infected by Meloidogyne incognita

Fluensulfone is the active ingredient of the non-fumigant nematicide Nimitz. It is much less harmful to the environment and has much improved worker safety compared to broad-spectrum fumigant nematicides. The product is registered for use in a variety of crops, including fruiting vegetables, and is applied to soil 7–14 days before seeding or planting. Although labeled for soil application, earlier research suggested that fluensulfone has systemic nematicidal activity when applied as a leaf spray application but also may cause some phytotoxic effects in some crops when applied as a leaf spray. In replicated greenhouse pot experiments, the nematicidal activity and phytotoxicity of fluensulfone applied as a soil drench was compared to a leaf spray application in tomato, eggplant, melon, and three pepper cultivars. A leaf spray application with fluensulfone significantly reduced Meloidogyne incognita infestation of the roots but was highly phytotoxic to melon and eggplant. Tomato and particularly peppers were less sensitive to fluensulfone leaf sprays. In further experiments we showed that the active ingredient is exuded or leaks out of the roots into the rhizosphere as spraying tomato or pepper plants with fluensulfone resulted in a high mortality of M. incognita second-stage juveniles in a water suspension surrounding the roots. This effect was observed within 12–24 hr after the spray application.