Gray Leaf Spot

leaf spot grass disease
leaf spot grass disease

South (only)

Warm Season Grasses

Grass species affected

  • Bermuda
  • Perennial ryegrass
  • St. Augustinegrass
  • Tall fescue
  • Other warm-season grasses

Disease occurrence

  • Late-spring through summer


  • Initial symptoms appear as narrow, dark-brown spots on leaf blades that enlarge over time into oblong to irregularly shaped lesions with dark-tan centers and dark-brown to purple margins.


  • Prevent gray leaf spot by maintaining a regular fertilization schedule using a fertilizer that releases nitrogen slowly, such as Milorganite.
  • When a gray leaf spot is present, it can be managed with an application of quick-release nitrogen.
  • Water deeply and infrequently early in the day to allow the leaf blades to dry off and not remain wet for long periods of time
  • Mow unaffected areas first and diseased areas last to avoid infecting a healthy lawn.
  • Collect and dispose of grass clippings in the garbage when rust is present.
  • To avoid spreading the fungus, after mowing, clean the mower blades by rinsing with water and drying with a cloth.
  • If gray leaf spot is persistent, consider replacing your lawn with a St. Augustinegrass cultivar derived from “Bitterblue,” which offers greater resistance to gray leaf spot.


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