Photo by A. H. McCain

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Hosts

Red fescue, perennial ryegrass

Symptoms

Red thread may kill grass in circular to irregular patches 2 to 8 inches (5 - 20 cm) in diameter or it may weaken turf. Leaves turn tan in color, giving the turf a scorched appearance. Infections on leaves begin at the tip and move down the blade. A pink web of fungal threads binds the leaves together. Pink, gelatinous fungal crusts occur on the leaves.

Conditions favoring disease

Red thread is favored by mild air temperatures (60° to 75°F) and extended periods of leaf wetness. Plants deficient in nitrogen during periods of cool temperatures or excess wetness can make the turf more susceptible to infection. In California it occurs primarily in northern and central coastal areas.

Prevention and management

Follow proper irrigation and fertilization requirements for your turf species. Provide adequate air circulation and reduce shading. Fungicides should not be needed.

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