Abstract: A blower device for producing a flat, sheet-like stream of air or gas is disclosed. An elongated, tubular body having one end closed and a slot opening along its length is supplied with air or gas under pressure at its other open end. A flat nozzle section fixed to the slot opening extends tangentially from the body. A series of twisting vanes within the body force the incoming air or gas into a spiral or helical flow pattern causing it to flow easily through the slot opening into the nozzle section. Straightening vanes are provided within the nozzle section to assure that the flow rate is substantially even along the outlet of the nozzle section. The blower device is mounted in combination with a grain or seed harvester forwardly of its cutter bar so as to blow rearwardly and prevent grain or seed from plant stalks from falling on the ground as the harvester moves along.