Red fescues are susceptible, too, but perennial ryegrass is not. Control is difficult. It is suggested that cultural modifications are the best way to slow down the disease. Fertilize moderately to promote growth during April to mid-May, late August and early September, or late fall. Do not starve the lawn.
Compaction is often times associated with affected areas.
Aeration with a spading fork may be beneficial. You can use a fungicide if you detect the problem early. Chemical treatment is expensive and not always effective. Lawns that are badly infected, layered with poor root development, or thatchy, are not good candidates for effective chemical treatment. You can find illustrations and additional information at your county extension office.