Zoysia grass is a warm-season perennial grass that spreads through deep rhizomes. The rhizomes will reach depths in excess of 18 inches and are difficult to kill. In most cases, firmly established zoysia will take multiple attempts to get rid of over the course of the summer.
Apply the herbicide glyphosate to the green zoysia grass, during the summer, at its height of growing. Mix the herbicide according to labeling directions.
Spray the zoysia grass with the chemical to thoroughly coat the blades. Keep the nozzle sprayer low to the ground so any over spray will not damage other plants.
Inspect the zoysia in two weeks after the initial application. Re-spray the herbicide on any green portions of the turf grass.
Repeat every two weeks until the grass is brown, before the first frost. The brown grass should rake or pull easily from the soil if the plant is dead. According to the University of Nebraska, it may take five or six applications to kill the rhizomes of the zoysia.