Common Lawn Fungus Diseases: Leaf Spot, Melting Out & Necrotic Ring Spot

Three fungal diseases cause major lawn damage. Correct ID leads to targeted treatment.

Leaf Spot (Bipolaris sorokiniana)

Purple-brown spots on blades; untreated → crown/root rot → thin lawn.
Treatment: proper mowing height, avoid constant wetness, water weekly (morning only). Fungicide if severe.

Spring/fall; reddish-brown rings + black "threads" on crowns.
Treatment: aggressive dethatching (thatch spreads it). Fungicide helps but not without dethatching. Reduce nitrogen. May take 2 years to control.

Lawn Care: Red Thread Fungus in Maryland Tall Fescue: The Organic Fix; Mowing Height with Fungus: 3 Inches Is Ideal Regardless; Lawn Service Fungicide Failure: Kentucky Bluegrass in Virginia; Rescuing a Chemically-Dependent Hamptons Lawn: Organic Rehabilitation; Diagnosing Yellow Patches in a Northeast Lawn: Zoysia Dormancy or Fungal Disease?; Summer Dormancy in Tall Fescue: What to Do (and Not Do) During Heat Waves; Blue Substance on Grass Blades: Fungal Disease Identification and Treatment; Lawn Disease Control: Identification, Prevention & Management; Snow Mold on Lawns: Identification, Treatment & Prevention; Lawn Rust Fungus: Identification, Impact & Cultural Control

Garden Articles

Plants