SEASON: Midsummer to fall.
APPEARANCE: The lawn takes on a rust-colored cast, especially noticeable from a distance. Dust-like spores, the main symptom of this disease, form in circular or elongated groups on grass blades. Anything moving through a severely infested area will be covered by the spores, and may spread the disease.
FAVORABLE CONDITIONS: Moderately warm, moist weather. Dew that lasts for 10 to 12 hours promotes germination. Stress that restricts growth favors rust.
SUSCEPTIBLE GRASSES: Can affect most types of turfgrass, but Kentucky bluegrass is damaged most frequently.
RESISTANT VARIETIES: 'America' and 'Eclipse' Kentucky bluegrass, and 'Manhattan II' perennial ryegrass.