A weed control root barrier includes a polymeric sheet material having spaced apart nodules or disks comprising a polymer containing a herbicide. The sheet is porous to permit free passage of water. It may be a non-woven fabric of non-biodegradable polyolefin material. Diffusion of the herbicide directly into the soil is controlled by a barrier material coated on selected portions of the nodules or disks. In one embodiment, essentially all the herbicide in the nodules or disks is directed into the soil via long term migration through and away from the sheet. The barrier layer is coated on portions of the nodules or disks facing the back surface of the carrier to block release of the herbicide to areas of the soil where it is not needed. Exposed surface portions of the nodules can be coated with the barrier material, leaving uncoated sides of the nodules from which herbicide may be released into the soil along a narrow zone of protection generally parallel to the front face of the carrier.
