Red Thread Lawn Disease

Red Thread Lawn Disease

Identification: Red Thread, as the name suggests, appears as pinkish-red threads that form around leaf blades and bind them together. When it first affects a lawn, areas infected will seem water-soaked or greasy green in appearance. As it progresses, the grass affected by the disease will become brown. The areas with the disease will have a bleached, patchy appearance and range anywhere from a few inches to several feet across. During periods of wet weather, the infected grass leaves will often become covered with a gelatinous pink fungus made up of the bright red, threadlike strands that make up this disease.

Cause: The fungus that causes this disease prefers cool, humid weather to grow in. The best temperatures for its development is from 68-75 degrees. If you have a lawn with a grass type that is susceptible to Red Thread, it is best to keep an eye out for its development during periods where conditions are favorable to its development. Taking precautionary measures is also advised.


  • Aerate your lawn regularly
  • Remove thatch build-up
  • Mow your lawn to its proper levels, determined by the type of grass you have
  • If possible, reduce the shade that falls on your lawn
  • Follow a regular fertilization schedule, including nitrogen and potassium

Treatment: Treating this disease isn't that difficult. Fungicides, such as chlorothalonil, can be used, but, often, they are not necissary. By simply fertilizing properly, collecting grass clippings while the disease is active, and watering deeply while avoiding frequent, light waterings, especially in the late afternoon, you should be able to help reduce the damage caused by this disease while helping your lawn recover.

Grass Types Susceptible: The most common grass types that are affected by red thread disease are Bluegrass, Ryegrass, and Fescue.