An improved assembly is provided for mounting a disk blade to the drawbar or standard of a furrow opener on a grain drill, planter or similar implement. A bearing support is attached to the drawbar. A bearing includes an outer race held by the bearing support, an inner race extending axially beyond the support and a single disk blade receiving bolt depending from the inner race. A disk blade is secured on the bolt between the inner race and a securing nut threaded on the end of the bolt so that the bolt, disk blade and inner race rotate together about the axis of the bolt. Since the bearing is not riveted or otherwise supported on the disk blade, the blade can be removed from the bolt and replaced easily and quickly without having to replace the bearing. The bearing case normally riveted to the disk blade is eliminated increasing the clearance between blades for better flow of dirt and trash.