Quick answer
Large patch is a fungal disease that hits zoysia (and sometimes Bermuda) in spring and fall when the weather is cool and wet. It shows as large brown circles, often with orange edges.
Conditions That Trigger It
- Soil temperatures in the 60s
- Long periods of leaf wetness
- Poor drainage and heavy thatch
- Evening or night watering
Prevention
Water early in the morning, improve drainage, and avoid fertilizing in fall. Preventive fungicides in early fall help lawns with a history of the disease.