Abstract: An improved pop-up irrigation sprinkler with integral flow control valve, and an improved separate flow control valve, defined by a dual flowpath for pilot flow within the flow control valve; a stem-flushing feature using an interrupter disc (54) mounted on a piston (48), providing a flowpath for a brief hydraulic flushing cycle after a momentary interruption of flow; a direct acting hydraulic pilot valve (92) to permit hydraulic control of an electric type sprinkler or a separate flow control valve; an improvement of the bearing guide (80) by the addition of a resilient barrier seal (84) to prevent seizing of the stem to the bearing guide when fully extended, the seal maintaining a close fit to the stem and yet being sufficiently resilient to permit the flushing of the stem; and a variable orifice in the inlet to the bonnet chamber to retard the initial opening rate of the valve.