Abstract: An orifice discharge device is provided for use in crop spraying aircraft to provide a downward spray of treatment substance especially liquid for crop or ground treatment. The device comprises an air passage having an inlet portion with a bell mouth, and an outlet portion having an Outlet discharge extending laterally relative to the inlet portion of the air passage, an elbow portion being provided between the inlet portion and the outlet portion. Treatment substance is supplied by a supply conduit to the outlet portion for discharge via a discharge nozzle of the supply conduit. In use, the inlet portion receives a horizontal flow of air and a high velocity downwards discharge of air with treatment substance (liquid particles) occurs from the outlet discharge of the outlet portion of the air passage. The device is preferably of streamline form.