WSU Extension

Hortsense

Lawn and Turf : Red thread
(revision date: 6/22/2015)


Biology
Red thread is a fungal disease common in cool, moist regions. It may occur on bentgrasses and bluegrasses, but is most common on red and chewings fescues and perennial ryegrasses. Infection can occur any time of year, but is most likely during fall, winter, and spring. Infected patches of grass first appear as watersoaked areas. The affected areas may be small to large and circular or irregular in outline. These later appear as diffuse areas of bleached or tan grass tips mixed with healthy grass. Fine pinkish to red threads of the fungus grow from the leaf tips. The fungus is spread by rain, wind, and contaminated mowers and other equipment. It can survive on infected grass and in the soil. Red thread infections are primarily an aesthetic concern, as they are rarely severe enough to kill grass. Low fertility greatly favors disease development.
Management Options

Non-Chemical Management
  • Hard fescues are resistant to red thread.
  • Provide proper culture. Adequate, balanced fertilization will help prevent red thread and other diseases. For more information on control of red thread see EB 0713, Diseases of Turfgrass.
  • Irrigate in the mornings so grass can dry quickly. Deep, infrequent watering is best.
  • Collect infected grass clippings to help reduce spread of disease.
  • For information on proper lawn care see EB0482E, Home Lawns.
Select non-chemical management options as your first choice!

Chemical Management

Not recommended for home lawns. Focus on cultural control methods.

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Caption: Red thread
Photo by: R.S. Byther
Caption: Red thread fungus
Photo by: R.S. Byther
Caption: Red thread fungus
Photo by: R.S. Byther