Sweep retaining structure includes a spring wire retainer with a base supported in a groove on the underside of the wedge support which mates with a stem portion of the sweep. The wedge support is apertured, and a central curved portion of the retainer passes through the aperture and supports a sweep-contacting end above the surface of the wedge support. The end is biased toward a contact area on the sweep to engage the area and eliminate sweep loss problems by preventing the sweep from slipping downwardly from the mounted position. To remove the sweep, a tool is inserted through the slot to depress the retainer end, and the sweep is forced off the wedge support. A raised area on the sweep directs soil away from the retainer and contact area to reduce wear and eliminate depression of the end during operation. The underside of the raised area positions the wire end and provides bend-resisting support for the wire.