Rust is a fungal disease (Puccinia sp.) that often appears in lawns in late summer. It is a disease of stressed lawns, and it is usually most common on perennial ryegrass, tall fescues and some cultivars of Kentucky bluegrass. Grass that is growing slowly under stressful conditions is most susceptible to rust, especially when water, nutrition, and soil conditions are limiting. Rust is also favored by warm, cloudy, humid conditions, followed by hot, sunny weather.
Symptoms include small, orange, blister-like pustules on leaf blades. These contain powdery, orange spores that often cover mowers, shoes, pets, etc., when activity occurs on the lawn. Affected areas in the lawn turn yellowish-orange in color. Fungicides to control rust are not recommended for home lawns; fertilizing the lawn in late summer and fall and irrigating to promote growth along with appropriate mowing practices are the best options for managing it.
