What are the small brown circles in my Bermuda?
Dollar spot disease of Turfgrass is named for the straw-colored, silver dollar-sized spots that appear. The disease causes larger spots on higher cut Turfgrass 3 to 6 inches in diameter. The typical dollar spot lesion is straw colored and girdles the entire leaf blade.
Dollar spot is most common in early/late summer and early fall in humid weather with warm days and cool nights. It survives as resting mycelium in the thatch. In humid weather, the grass plants exude sugars and other nutrients during the night in droplets. This provides a nutrient source for the fungi to begin to grow on the surface of the leaf blades and initiate infections. Turf grasses appear to be more susceptible to infection when nutrient-deficient and when the soil is dry, probably because both factors reduce the growth of the grass.
Usually, only the leaf blades become infected. Dollar spot rarely causes severe damage on lawn grasses. Dollar spot disease usually occurs on lawns that are water and nitrogen-deficient. Application of fertilizer will stimulate growth, so the infected leaf blades may be mowed off. Sufficient water should be applied when rainfall is sparse. Thick thatch stresses the Turfgrass and increases dollar spot. If dollar spot is present in the lawn, it is best to mow only when the grass is dry to prevent spreading the fungus, and to remove the clippings. Mow the grass high and do not remove more than 1/3 of the leaf blade at a single cutting to avoid stress. Water deeply and infrequently. Light sprinklings, especially late in the day, will increase disease. Increase air movement by pruning trees and shrubs so the grass will dry more quickly.
Dollar spot disease responds readily to fungicides, but application of fertilizer and attention to watering practices is usually sufficient to minimize the disease. Dollar spot rarely causes sufficient injury to lawns to justify the use of fungicides.