Dollar Spot Fungus

July 22, 2014
  • Dollar spot fungus in lawn

Dollar Spot Fungus

Dollar spot fungus on Bluegrass

Dollar spot fungus on Bluegrass

The presence of dollar spot in a well-managed turf affects its aesthetics or recreational use, but is usually not a threat to its survival. Dollar spot is caused by the fungus Sclerotinia homeocarpa.

Warm days and cool nights that produce dew and high humidity in the turf canopy are ideal conditions for dollar spot. Under these conditions, the dollar spot fungi produce mycelium on the surface of grass blades, which is spread with the clippings, mowers, and foot traffic. Dollar spot can appear any time from late spring through late autumn and may become severe in turf deficient in nitrogen.

Overall disease appearance on closely mowed bentgrass golf greens are found, light tan spots ranging from the size of a quarter to a silver dollar. On turfs maintained at 1 to 3 inches, symptoms appear in a mottled, light tan pattern made up of 4- to 6-inch patches of blighted turf. Individual leaf blades will develop a lesion that may be up to an inch long, is light tan with reddish-brown margins, and usually spans the width of the blade. When dew is present, the mycelial growth on the grass blades looks like a cobweb.

Dollar Spot Treatment

Dollar spot often can be prevented without the use of fungicides or with minimal fungicide application. Proper fertilization to ensure vigorous, but not overly lush growth, morning watering, reducing thatch and compaction, and early morning syringing to reduce dew are usually sufficient to prevent damaging outbreaks. If needed, a fungicide can be applied at the first appearance of dollar spot.

Brown Patch

Brown Patch fungus is also currently present in turf as of June 19, 2014.  Click here to learn more about Brown Patch.

Dollar Spot Information courtesy from the University of Nebraska-Lincoln, Turfgrass Science Team  turf.unl.edu and Omaha Organics staff.

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