There is presented a row marker adapted to be used with a tractor carrying seed-dispensing hoppers and having an hydraulic system and having a tool bar carried by the tractor for movement over the ground. The row marker comprises a frame for mounting on one end of the tool bar and carrying a pivoted first arm portion of the marking arm for oscillation between a substantially horizontal working position and a substantially vertical carrying position. A second arm portion of the marking arm has one end pivotally attached to the outer end of the first arm portion at a pivot shaft for oscillating movement between a generally vertical carrying position close to the first arm portion and a generally horizontal working position in alignment with the first arm portion in its working position. A marking element, such as a disc, is attached to the outer end of the second arm portion. The novelty consists in the pivoting and locking parts connecting the first arm portion to the second arm portion, these parts consisting entirely of rigid members pivotally connected to each other so as to provide an inexpensive and trouble free folding structure that will fold into a compact unit for transportation.