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Disease Profile: Red Thread

Red Thread is a disease that is common to turfgrasses during the early summer when conditions are high in humidity and rainfall. While red thread does not help your lawn in appearance, the good news is that it is completely curable!

Understanding Red Thread

The name “Red Thread” comes from the color infected leaf blade, making this disease easy to identify.

What It Looks Like – Red thread appears in lawns as pink or tan circular patches from a distance, however, up close it looks like pink and red threads running through your grass blades. The color is caused by a fungus that runs through, sometimes extending about 1” above, your grass. While this does make an unfavorable area on your lawn, only the grass blade is affected meaning this disease will not kill your grass. Red thread favors temperatures between 40*-70* and humid conditions making early summer a common time for this disease.

Prevention – Red thread favors warm humid conditions and is most common in under-nourished lawns. It is important to remember that just like you, your lawn needs nutrients to grow healthy and strong. Proper maintenance your lawn keeps it in good health and increases its ability to prevent disease and other problems. The good news is there are steps you can take to lower your risk and/or control the disease if your lawn already is showing signs!

  • Keep your lawn properly fertilized – make sure that you are on a consistent fertilizing schedule. This will help the disease (that effects the blade, not the root system) grow out of your lawn. It will also help prevent red thread from spreading by strengthening your existing turf.
  • Mow your lawn correctly – keep your mower blades sharp and your grass high (3.5”). If your lawn is already affected with red thread, when you mow we suggest you collect the clippings and dispose of them away from your turf to prevent spreading.
  • NEVER WATER AT NIGHT! – this makes your lawn a breeding ground for disease as water will sit too long on the soil line. Please take rainfall into consideration, 1-2” of water a week is all your lawn needs! Learn more about proper watering techniques.
  • Thatch – heavy thatch layers and/or compacted soil are one of the contributing factors for any disease in the lawn. If your lawn hasn’t been aerated in a while or is showing red thread or other disease it is time to consider aeration to help reduce thatch and soil compaction and promote a thick healthy turf. Learn more about aeration or order aeration this fall!

Treatment – Good news!!! Red Thread is a disease that does not need a fungicide in order to be corrected. Red thread is largely cosmetic and your turf will recover. This disease shows up in lawns during the spring and early summer due to weather conditions. By following the tips for prevention above, it will also help take care of any red thread that is currently in the lawn. The diseased parts of the plant will grow out on its own and be removed completely as you mow. To speed the process of elimination, make sure you are on a regular application schedule for fertilizing treatments. For lawns with a history of red thread, make sure that you get your fertilizer treatments in the early and mid spring and consider aeration every year to improve the health of your lawn.

Read More: Watering Techniques, Early Summer Treatment, Aeration & Seeding

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