A shield apparatus is mounted on the header of an agricultural implement which includes a rotatable collecting member to direct collected material rearwardly towards a rear discharge opening. The shield apparatus includes a panel member and a mounting bracket assembly which supports the panel member above the rear discharge opening of the header spanning in a lateral direction transversely to the forward working direction such that the panel member extends from a rear edge rearward of the collecting member to a front edge which is spaced forward and upwardly in relation to the rear edge. The shield apparatus ensures that material thrown upwardly above the rear of the header frame is redirected downwardly into the rear discharge opening of the header for collection by the implement in the usual manner. The shield apparatus does not interfere with the visibility of the operator when the panel member is clear.