Abstract: A modular weed barrier mat comprised of a double layer of tire tread sections cut from used tires arranged so that the lengths of the upper sections are perpendicular to those of the lower sections. A pair of upper sections are positioned in spaced apart relationship so as to form a gap, with a central slit array cut into two immediately adjacent lower sections accessible within the gap. A slit cut through a width of one lower section directly below one of the upper sections on either side of the central slit array allows a post to be moved into the slit and then positioned in the central slit array. Corrosion resistant fasteners are removed and replaced as needed to allow the mat to be installed or removed as desired. One embodiment features lower and upper lap portions on opposite sides of the mat for modular installation.