Necrotic Ring Spot

Pathogen: Ophiosphaerella korrae

Identification

Symptoms

  • Light-green spots enlarge into 1-3 ft patches
  • Reddish-brown to bronze turf fades to straw
  • Frog-eye ring patterns can appear as turf recolonizes centers
Season
Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov
Regions
Northeast, Midwest, Mountain West, Pacific Northwest, Transition Zone
Turf Hosts
Kentucky Bluegrass, Fine Fescue

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This is identification help, not a diagnosis. Symptoms described here can overlap between diseases and other causes (drought, wear, nutrient deficiency). When you're not sure, or before applying any treatment, contact your state's Cooperative Extension office - most offer free or low-cost diagnosis and know your local conditions best.