Homeowners often plant zoysia grass because it requires less water or fertilization, and generally less attention than other grasses. Like most other plants, however, it is plagued with its own problems that vary in seriousness. Knowledge of these problems can help you identify them early and decide which treatment the zoysia grass needs.
Zoysia grass grows slowly but develops thatch quickly. This accumulation of living and dead zoysia tissue can become a problem when it reaches 1/2 inch thick. At this point, it decreases the ability of the turf to take in water, reduces stress tolerance and harbors pests and diseases. To prevent the buildup of thatch, mow the lawn to 1 to 2 inches every five to seven days. If thatch becomes a problem, a power rake or a core aerifier will help thin it out.
Dollar spot, brown patch and rust are the diseases that most often affect zoysia grass. These create brown patches of varying sizes on the turf. You can suppress all these diseases with proper watering, fertilization and aeration. Zoysia patch can become a chronic problem, however, even in well-maintained grasses. Applying a preventative fungicide in the fall will help the turf fight off this disease.
Chinch bugs are the most common pest in zoysia grass. They suck sap from the leaves and stems, which turn yellow and then reddish brown. This occurs most often in July and August, during the hottest days of the year. Nematodes, which attack the roots, are another serious problem. White grubs and billbugs also affect the grass. All these pests, when they become a serious problem, can be controlled with insecticide applications.
As the zoysia grass is so thick, weeds are not often a problem. Crabgrass and some annual grasses can become a problem with zoysia grass that is not yet established. Control these weeds with a pre-emergent herbicide. You can use standard herbicide on broadleaf weeds that creep through.