3 Most Common Zoysia Grass Diseases & How to Treat Them

Homeowners searching for a vibrant, resilient lawn that withstands heat, drought, heavy foot traffic, and various challenges often find their match in Zoysia grass.

Zoysia grass is a warm-season variety that spreads by stolons and rhizomes. Although it may take longer to establish, Zoysia matures into a dense ground cover with fine-to-medium leaf texture and a delightful light to emerald green grass blades that turns brown when the temperatures drop in winter. Under optimal conditions, it creates a durable, low-maintenance lawn with remarkable resistance to weeds and diseases.

Zoysia Patch Fungus & Other Common Diseases

While Zoysia grass is less vulnerable to fungal diseases than other warm-season grasses like Bermuda grass, that doesn't mean it's immune to damage and infections.

Brown Patch

Brown patch fungus is most prevalent on Zoysia grass, initially appearing as small circular patches of brown, dead grass. These brown patches can expand and merge, forming larger areas spanning several feet in diameter.

Extended exposure to moisture from heavy rainfall, inadequate drainage, or poor irrigation practices create the ideal environment for this fungal disease. While it commonly occurs in the spring, it can also affect lawns during the fall when warm-season grasses experience slower growth or go dormant due to cooler temperatures. Periods of flooding or heavy rainfall can also contribute to the emergence of this fungal issue.

Dollar Spot

Zoysia grass is also susceptible to dollar spot, a lawn disease recognized by straw-colored spots or lesions on grass blades, usually the size of a silver dollar—hence its name. These spots can extend from the blades to the tips, resulting in wilting.

Dollar spot is prevalent in high-humidity conditions, often linked to excessive thatch buildup, improper mowing practices, and weeds. Additionally, a deficiency in nitrogen fertilizer is associated with the occurrence of this fungal disease.

Rust

Rust in grass is attributed to the Puccinia genus fungus and usually develops in prolonged wet conditions or persistent drought. This lawn disease manifests as an orange-to-red, powdery film on the grass that you can easily brush off. It also disperses reddish-orange dust when mowed.

In contrast to other fungal diseases, lawn rust is easier to identify and, consequently, easier to treat.

How to Treat and Prevent The Most Common Zoysia Lawn Diseases

These lawn diseases often stem from specific environmental conditions, primarily excessive moisture. While accurate identification is crucial for treating them, addressing the root cause is equally imperative.

It's also essential to recognize that not all lawn damage is attributed to fungal diseases. Sometimes, inadequate lawn management practices contribute to problems such as thatch build-up and poor drainage. Overall, this highlights the importance of a comprehensive approach that involves proper identification and correction of underlying environmental factors in treating and preventing fungal infections.

Dethatch Your Lawn

Zoysia grass, known for its resilience against pests and diseases, is susceptible to thatch buildup—a layer of organic matter composed of dead stems, leaves, and roots that accumulates at the grass base where it meets the soil. While a small thatch layer is normal and beneficial for the grass, an excessive buildup can prevent air, water, and nutrients from penetrating the soil, potentially leading to nutrient deficiencies and stunted growth.

Dethatching is deemed necessary when the thach exceeds half an inch in thickness. While a garden rake can handle a slightly thick thatch, a vertical mower equipped with vertical blades is more effective in cutting through and removing a thicker thatch layer.

Mow at Proper Heights

Another maintenance issue that can contribute to Zoysia grass diseases is improper mowing. Infrequent mowing is known to foster thatch buildup, while mowing too often and too short may result in scalping, exposing the grass crown to adverse weather conditions.

Although Zoysia grass can endure lower cutting heights, we advise maintaining a grass length of 2 to 2 ½ inches and adhering to the one-third rule—cutting no more than one-third of the grass height each mowing session.

Water Deeply But Less Often

Zoysia grass is favored for being remarkably drought-tolerant, lasting up to six weeks without water while in a dormant state. However, the drawback lies in its sensitivity to excessive moisture.

Overwatering can lead to standing water, causing the grass to turn brown due to root rot or disease. To prevent this, we advise watering your lawn with 1 inch of water per week or up to 2 inches during exceptionally hot weather. The optimal watering time is in the early morning, allowing water to dry throughout the day.

Aerate Your Lawn

Aerating your lawn helps alleviate soil compaction, which restricts air circulation, resulting in oxygen deficiency and stunted root growth. You can aerate your lawn by digging with a spading fork or rototiller to a depth of 8-10 inches to loosen the soil. Alternatively, you can use a grass plug tool to extract small soil plugs, allowing the air to reach the roots.

Fertilize as Necessary

Much like mowing, it's essential to find the right balance in fertilizing your lawn. Too much fertilizer can harm your grass, potentially causing burns or nutrient leaching. Meanwhile, insufficient fertilization may lead to nutrient deficiency, weakening grass and making it prone to diseases.

For your Zoysia lawn, we advise fertilizing during its active growth period, usually from late spring to early fall. Additionally, it's essential to tailor your approach to your lawn's specific needs. A soil test can precisely identify soil pH and nutrient composition, helping you make informed decisions about the amendments required to sustain an optimal nutrient balance and cultivate a lawn resistant to diseases.

Apply Fungicides

While some fungi will naturally run their course, others necessitate treatment. Besides addressing the source, it's crucial to positively identify the specific fungus affecting your lawn.

Once identified, use the appropriate fungicide tailored to that particular fungus. Follow the instructions on the label, particularly application rates and timing. Apply the fungicide uniformly over the affected area, extending the treatment slightly beyond the visible infection zone. Repeat applications as necessary.

Repair Fungal Damage with Zoysia Grass Plugs

Fungi are consistently present in your lawn, lying dormant until triggered by specific conditions. The key to keeping them at bay is maintaining proper lawn maintenance practices.

While Zoysia grass is known for its resilience, it's not invulnerable, and addressing fungus damage and planting grass plugs are necessary to restore your lawn to its vibrant, green state.

Zoysia grass plugs prove to be a reliable and effective way to repair damaged areas. Planting these plugs not only facilitates faster recovery but also promotes healthier and denser turf that is more resistant to pests and diseases. For an added nutrient boost, we recommend supplementing your plugs with NutriPod, a slow-release lawn fertilizer that delivers essential nutrients directly to the planting site, promoting successful establishment.

Has your lawn been infected with fungi disease? How did you address it? Let us know by leaving a comment.