Keep red thread eye sores out of sight

By Lisa Beirn, Ph.D., technical services manager for Syngenta

Red thread is a fungal infection that causes reddish-brown patches on customers’ lawns. The disease can be found on all turfgrass species, but perennial ryegrass is particularly susceptible. It may kill turf in patches that are 2-8 inches in diameter, or the disease may occur over large areas without killing the plants. A pink web of fungal threads binds the leaves together. To help identify this disease, look for pink, gelatinous fungal crusts projecting from the leaves.

Source: Syngenta, 2016.

Conditions for development

The pathogen prefers temperatures between 59-77 F, however it can grow under a wide range of temperatures (37-86 F). The disease is commonly found in the spring and fall in locations that are low in nitrogen. It also occurs in areas that experience more than 10 hours a day of foliar wetness for several consecutive days.

Control measures

  • Mow turf frequently and collect clippings to remove diseased portions of the leaves
  • Maintain adequate nitrogen and a balanced fertility
  • Apply moderate-to-high amounts of phosphorous and potash
  • Maintain the soil pH between 6.0 and 6.5
  • Reduce shade
  • Increase air circulation to help the turf's drying process
  • Irrigate turf deeply and as infrequently as possible

Compendium® and Velista® fungicides are ideal solutions to help control red thread. Preventive and early curative applications will provide the best results. The graph below demonstrates excellent red thread control with Velista fungicide when applied curatively.



​​​​​​​Rutgers University, 2011


​​​​​​​Performance assessments are based upon results or analysis of public information, field observations and/or internal Syngenta evaluations.

For more information about red thread that you can share with your customers, download our red thread door hanger.


All photos are either the property of Syngenta or are used with permission.

© 2024 Syngenta. Important: Always read and follow label instructions. Some products may not be registered for sale or use in all states or counties and/or may have state-specific use requirements. Please check with your local extension service to ensure registration and proper use. Compendium®, Heritage®, Velista® and the Syngenta logo are trademarks of a Syngenta Group Company.

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