Photo by A. H. McCain

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Hosts

Annual bluegrass (a common weed in turf), Kentucky bluegrass, perennial ryegrass, tall fescue

Symptoms

Affected leaves and stems turn yellow and are covered with reddish-brown pustules with dusty spores. The yellow spots start small but the entire leaf may soon turn yellow. The entire turf may take on a rusty color and look thin and weak. Orange spores rub off when leaves are handled.

Conditions favoring disease

Moderately warm air temperatures (70° to 75°F) and extended periods of leaf wetness favor the development of rust. Turf that is deficient in nitrogen is more susceptible to disease development.

Prevention and management

Maintain turfgrass vigor by following proper irrigation and fertilization requirements for your turf species. Mow regularly and remove the clippings to reduce the number of spores if the lawn is infected . Rust can be managed by following proper cultural practices, and fungicides should not be needed.

For more information on lawn diseases, refer to:
Pest Notes: Lawn Diseases: Prevention and Management