A telescoping row marker for use with a conventional agricultural tillage apparatus such as a tractor carried, or pulled, planter, cultivator or the like; for the alignment of soil working implements with crop rows is disclosed. Positioned within a hollow mounting bar open at both ends are first and second telescoping marker arms having marking means attached to the distal ends and engageable track means located along the length thereof. Positioned adjacent respective ends of the mounting bar are first and second drive means engaging the track means of an adjacently positioned marker arm for displacing the marker arms along the hollow mounting bar whereby the marker arms may be fully extended in the working position or may be fully retracted for transporting or maneuvering the tillage apparatus. Intermediate marker arm positions are available to accommodate various row widths with each marker arm including a vertically hinged portion to allow for free marker vertical displacement for contour following and in the event of impact with an obstacle. In addition, each arm includes a horizontally hinged shear pin coupling to permit the horizontal breakaway of the arm upon impact with large obstructions such as rocks or trees. The marker arm drive means may be operated from the tractor's hydraulic system with independent control of each marker arm provided.