An articulated nozzle-holder boom arm for agricultural sprayer which is extensible to the sides of a main chassis and which can be folded to a transportation position by means of an intermediate hinge generally placed in an intermediate point of the boom arm, and the several sections of the beam forming the boom arm can be engaged or disengaged easily and without welding in the hinge or several supports of the beam sections, being the beam sections generally extruded aluminum profiles and the union of the profiles ends obtained engaging the same in retaining flanges included in the supports and hinges of connection of the sections.