Problem: Rust (Lawns)
This lawn disease is caused by a fungus (Puccinia species) that occurs most frequently on Kentucky bluegrass, ryegrass, tall fescue, and zoysiagrass. It is most active during moist, warm weather (70° to 75°F) but can be active all winter in mild winter areas. Heavy dew favors its development. Grasses under stress from nitrogen deficiency and lack of moisture are most susceptible to attack. Rust is also more severe in the shade. The orange powder is composed of millions of microscopic spores that spread easily in the wind. Lawns attacked severely by rust are more likely to suffer winter damage.
Rust develops slowly, often more slowly than the grass grows. Apply a high-nitrogen fertilizer to maintain rapid growth. Mow frequently, removing the clippings.