Lawn rust disease: when it matters

Lawn rust is visible, alarming-looking, and mostly harmless to established cool-season lawns. Walk through a rust-infected lawn and your shoes and pant legs turn orange -- the pathogen produces enormous quantities of orange urediniospores on leaf surfaces. The actual damage to the grass plant, in.

Lawn rust is visible, alarming-looking, and mostly harmless to established cool-season lawns. Walk through a rust-infected lawn and your shoes and pant legs turn orange — the pathogen produces enormous quantities of orange urediniospores on leaf surfaces. The actual damage to the grass plant, in most cases, is cosmetic.

Pathogens and host range

Per Penn State Center for Turfgrass Science, several rust fungi affect lawn grasses, most belonging to the genera Puccinia and Uromyces:

• Crown rust (Puccinia coronata) — perennial ryegrass, Kentucky bluegrass, tall fescue
• Stem rust (Puccinia graminis) — Kentucky bluegrass, ryegrass
• Stripe rust (Puccinia striiformis) — Kentucky bluegrass, ryegrass

Per NC State TurfFiles, crown rust is the most common on home lawns in the eastern United States.