Photo by A. H. McCain

Photo by Ali Harivandi

Photo by Bobby Joyner, ChemLawn Corp.

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Hosts

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

Symptoms

Dollar spot begins as small, circular spots 1 to 2 inches (2.5 - 5 cm) in diameter. Spots are straw colored or have a bleached appearance and merge together to form large, irregular areas. Individual leaves appear water-soaked, often exhibiting 2 reddish bands across the leaf in an hourglass shape. Fine, white, cobwebby threads may be seen in early morning.

Conditions favoring disease

Dollar spot appears during the spring and fall months in California and is favored by moderate temperatures (60° to 80°F). Excess moisture, water stress, fog, or thatch buildup can also contribute to disease development. Dollar spot survives in the soil as hard, dark structures called sclerotia.

Prevention and management

Apply fertilizer at the recommended rate for your turf species. Follow proper irrigation practices. Reduce thatch and maintain air circulation. Compost top dressings may suppress the disease. Increase your mowing height to the tallest recommended for your turf species. If dollar spot has caused a problem in previous years, a fungicide may be useful. Apply it in the early spring or fall before symptoms occur.

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