Red Thread Disease

Red thread is a fungal disease that affects lawns in wet, cool weather with pinkish red coloration that makes it easy to spot.  Because this disease does not infect the roots or crown, the effects are largely cosmetic as infected pants are not killed and will eventually recover.

What to Look For:

In the early stages of red thread, infected areas appear darkened or “water soaked” in irregular patches that range from a few inches to a few feet across.  These patches slowly turn tan in color and have a ragged look caused by scattered healthy plants within the infected patches.
As the disease develops, light pink or red mycelium fungus strands of ¼” or more grow from the tip of the blade and the sheath.  The threads spread infection by touching surrounding plants or having bits of it blown in the wind to non-infected areas.  Red thread’s inability to completely wipe out areas of turf makes lawns appear uneven and patchy.


Red thread disease is the most common in cool temperatures between 68 and 75 degrees and conditions of excessive moisture or humidity.  This disease is also active in lawns with low levels of nutrients such as nitrogen or calcium.  Kentucky bluegrass, perennial ryegrass, and tall fescue are the most commonly affected grass types as well as areas of low maintenance turf such as residential lawns and athletic fields.  Under these conditions, red thread can spread quickly over an area of turf.

Red Thread Control:

Red thread is a weather related disease that thrives when the conditions are ideal for its growth.  The best methods for controlling red thread involve minimizing moisture in the lawn and providing proper nutrients to discourage its growth.

  • Administer fertilizer applications with adequate nitrogen levels in the spring and fall
  • Follow proper watering practices and avoid irrigation practices that could lead to excessive moisture such as watering before dark
  • Reduce shade areas to avoid extra moisture
  • Lawn aerations in the fall and spring help fight red thread

If you think Red Thread is infecting your lawn, don’t hesitate to contact us to assess your problem and provide a solution.
For more information about this and other lawn diseases, visit our disease prevention page.

2018-04-06T17:35:36+00:00 Lawn Diseases|