A device for restricting water flow through a conduit in a landscape sprinkler system, wherein the conduit comprises a hollow pipe having an interior wall, the device comprising a generally rigid disc having an external periphery shaped to conform to the interior wall of the conduit; attachment means for frictionally securing the disc traverse to the interior wall of the conduit, and, at least one aperture in the disc to permit water flow therethrough, wherein the total area of any apertures in the disc are from about 1% to about 40% of the cross-sectional area of the disc.