Abstract: A seeder of the type adapted to be pulled behind a tractor for seeding a field is provided with an extendable and retractable pivoted linkage assembly on each side of the seeder. A marking disk is rotatably mounted on the furthest extremity of the linkage and a hydraulic piston and cylinder assembly is connected between the two links closest to the seeder assembly for extending and retracting the linkage in a horizontal plane. A pair of support plates are secured to the underside of the two bars closest to the seeder assembly for engaging and supporting the other bars in the retracted condition. Another piston and cylinder assembly is mounted on the seeder and operatively engaged with a lever connected to one of said bars of said first pair of bars for pivoting the retracted linkage upwardly to provide clearance between the marking disk and the field.