Brown Patch - Cool Season Grass

Reduce fertilization to avoid Brown Patch, a hot weather lawn disease.


Grass species affected

  • Bluegrass
  • Fescue
  • Ryegrass 

Disease occurrence

  • Mid-June through early-September


  • Circular brown patches up to 3 feet in diameter that develop during hot, wet weather.
  • Infected leaf blades are dark, wilted, and die quickly.
  • The entire patch will eventually become brownish-tan.


  • Avoid using high-nitrogen fertilizers in late-spring through early-summer. Milorganite releases nitrogen slowly and can be used safely.
  • Reduce thatch to increase air circulation.
  • 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, as brown patch thrives in this environment.
  • Avoid excessive fertilization with high nitrogen fertilizers in late spring or early summer. Reduce thatch to increase air circulation, and water deeply but infrequently early in the day to allow the leaf blade to dry off.
  • Mow unaffected areas first and diseased areas last to avoid infecting areas of healthy lawn.
  • Collect and dispose of grass clippings in the garbage when brown patch is present.
  • To avoid spreading the fungus, after mowing, clean the mower blades by rising with water and drying with a cloth.

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