An earthmoving blade and mounting assembly 10, includes at least one generally hollow section mounting arm 12, 14 which mounts the blade 11 in use on an earthmoving machine, the arm 12, 14 including a generally sideways opening channel 20 and a generally upright closure plate 28 which closes the open mouth of the channel 20 to provide the hollow, the cross section of the hollow increasing from a mounting position 15, 16 where the arm 12, 14 is mounted on the earthmoving machine to an outer end where the arm 12, 14 is secured to the blade 11.