The first signs of rust are yellow lesions. Later, spores cover the blades. They are usually orange but may also be yellow, red, or brown. Wind and rain can carry the spores to cause new infections.
If the disease is severe, grass stands appear thin and discolored and the grass may eventually die. All lawn grasses are susceptible.
To prevent rust problems, keep leaves dry by watering only early in the day. Avoid stress from either too much or too little water. Prune trees and shrubs to increase light and air flow.
Mow to the correct height. Raking and removing clippings when the disease is present can reduce the number of spores to spread the disease.