Zoysia grass (Zoysia spp.) is a low-growing lawn grass with a fine, dense texture. Zoysia grass will tolerate shade, but prefers full sun. This grass grows on a wide variety of soils, and is moderately salt tolerant. Zoysia grass is considered a moderate maintenance grass because it requires less mowing than some species due its slow growth, however, it requires frequent irrigation and fertilization.
Zoysia grass is commonly established from sod, but is also started from seeds or sprigs. Zoysia grass is tolerant of wear and can be used for lawns, parks, and other public spaces. Some problems for zoysia grass include pests such as nematodes (microscopic worm-like organisms), mole crickets, armyworms, and sod webworms as well as fungal disease.
Rhizoctonia solani causes brown patch disease in turfgrass. Infected zoysia grass will contain brown areas of grass that quickly develop (within 24 to 48 hours) during hot, humid and wet conditions. This disease is common in home and commercial lawns and can be prevented with fungicide applications, but this disease usually does not kill the grass. Recovery is possible as soon as cooler, dryer conditions return.
Symptoms of brown spot vary depending on species and turf cultivation practices, but generally, 2- to 3-foot diameter blighted patches of grass will be evident, especially in the morning during warm, humid weather. A dark purplish gray border on diseased areas is a prominent diagnostic characteristic. Avoidance of wet soil and keeping zoysia grass foliage dry late in the day is the most important step to keeping brown patch from developing, according to an Ohio State University Extension Fact Sheet.
On zoysia grass lawns, rust disease will be seen as a orange or yellow-orange powder (from spores) on the leaf blades. Rust is seen most often during dry weather, such as in late summer and early fall. Rust typically grows on grass growing very slowly, which is a characteristic of zoysia grass species. The appearance of the zoysia grass lawn will have a yellowish, or brown or orange cast and the individual blades will contain spores that easily rub off.
Rust disease may weaken zoysia grass and make it susceptible to other disease. Cultural practices, such as watering early in the day to reduce moisture left on leaf blades, and fertilizing in September are ways to reduce the incidence of rust disease, as fungicides are generally not recommended for home lawns. Once the growing conditions of zoysia grass improve, the rust problem may disappear.
Leaf Spot Disease
Leaf Spot is caused by the fungus Bipolaris sorokiniana. Leaf spot on zoysia grass is easily recognized by observing distinctive small brown spots on yellowed leaf blades and thinning of the affected turf. Spots, somewhat longer than wide, extend along the leaf blade, which may have dead tips. Leaf spot is likely to occur during periods of dry conditions alternating with clouds and showers.
Proper watering and fertilization will reduce the occurrence of leaf spot (water in the morning and do not fertilize excessively). Commercial fungicides are available, but good cultural practices are the best management of disease in turfgrass.