Zoysia Grass Diseases

Zoysia lawns are usually free of disease. Occasionally a fungal disease appears under the right environmental conditions, but they will often fade away as the weather changes. Nonetheless, always be prepared to act if brownpatch, dollar spot, leaf spot, pythium, or rust arrives in your zoysia grass. These diseases are often prevalent in the spring and fall when daytime air temperatures are 60-80 degrees, nighttime air temperatures are around 60 degrees, and there is plenty of moisture on the grass. During these critical times, it is usually best to switch to a daytime or early morning (according to local regulations) irrigation schedule so that moisture will evaporate quickly from the zoysia grass leaves.

Fungal diseases are difficult to identify and are often attributed to other problems. In fact, many spring disease outbreaks are ignored until the diseased area grows into a sizeable problem. The best advice is to take a good look at your lawn every couple of days and to be aware of anything abnormal. In general, fungal diseases appear as brown or damaged patches of zoysia grass with clearly defined outlines. If you find a lawn area that fits this description, don't run out and spray the entire lawn with fungicide. Wait to see if the patch of damaged grass expands over the next day or two. It is quite possible that the fungal disease has already run its course. An "active" patch of diseased turf will grow and expand concentrically over a couple of days. Zoysia grass plants along the outline of the damaged patch will have the most telling signs: wilted plants, shriveled leaves, or discolored leaf blades. Rust is a common problem on zoysia grass in the fall and appears as reddish brown spots on the zoysia grass leaf blades. Once you have identified a disease outbreak, spray the affected area with a lawn fungicide approved for use on zoysia grass.

If your zoysia grass lawn has a history of fungal problems, you may want to renovate the dead areas then spray preventatively with a lawn fungicide the following year so that the disease does not recur. Follow the directions on the product label explicitly. You will probably need to spray several times over a 2 to 4 week period.

Over Seeding a Zoysia Grass Lawn

The primary reason we grow zoysia grass is because it is an incredibly thick grass. Unfortunately, this makes it very hard, if not impossible, to over seed zoysia grass for a winter cover. If you were wondering, over seeding is a method by which you sow a cool season grass like annual ryegrass into your zoysia grass or other warm season grass over the winter months. The problem with zoysia grass is that it is so thick that it is nearly impossible for the annual ryegrass to reach the soil surface and germinate. It is best to forget about over seeding and enjoy your zoysia grass for all its wonderful attributes.