What Are the Brown Spots on Zoyzia Grass?

Zoysia, a medium-textured, warm-season grass, grows best in areas of full sun. The grass is preferred for its low-water requirement and good pest resistance. Zoysia tolerates heavy traffic and drought. However, it is susceptible to a fungus that causes brown spots.

Identification

Zoysia is susceptible to pythium blight, also called grease spot, caused by the Phythium fungi. The disease is prevalent in over-watered lawns and in warm temperatures between 80 and 90 degrees Fahrenheit.

Damage

Phythium blight is characterized by the appearance of small circles of brown, dead areas on lawns. As the disease progresses, the spots enlarge and merge. Under optimal temperatures, the fungus spreads rapidly. Infected grass turns black and then assumes a reddish-brown color. The blades look greasy and stick together.

Management

Avoid excessive use of high nitrogen fertilizers in lawns or over watering. Mow grass when it is dry. Aerate grass and improve drainage. The University of California Extension cites proper irrigation as the key management strategy. Fungicides do not provide adequate control.

References

• University of California Extension: Zoysiagrass
• University of California Extension: Phythium Blight