What is Red Thread and How to Get Rid of It

close-up of red thread disease on grass blades

If your grass looks like it’s covered in pink silly string –– and you didn’t just throw a party –– then your lawn may have red thread disease. But before you go on a fungicide frenzy, it’s important to learn what red thread is and how to get rid of it. You might be surprised to learn that fungicides aren’t the best treatment for this turfgrass disease. 

How to identify red thread

From a distance, red thread symptoms appear as pink or tan circular patches 1 inch to 2 feet in diameter. Upon closer inspection, you may notice the patches contain a mix of healthy green grass and diseased grass that’s tan or white.  

The turfgrass disease resembles similar symptoms to pink snow mold, dollar spot, and pink patch disease. But you can easily distinguish red thread by the pinkish-red, antler-like threads (known as sclerotia) that protrude from the tips of infected grass blades. 

The ½-inch sclerotia are sometimes accompanied by pink, web-like mycelium when conditions are wet and humid. The stringy sclerotia coupled with the fuzzy mycelium is what earns the disease its memorable name (and makes your lawn look like it’s having a bad hair day). 

What causes red thread in the yard?

Many factors can make your yard an attractive host for red thread’s causal agent, Laetisaria fuciformis. If red thread is growing in your lawn, here are some environmental conditions that could be contributing to the disease’s success: 

  • Red thread can develop when air temperatures are between 40 and 75 degrees Fahrenheit. The optimal temperature range is 60 to 75 degrees Fahrenheit. 
  • The disease favors high humidity and excessive moisture. 
  • Red thread can occur at any time of year, but is most severe in spring and fall when conditions are cool and wet. 
  • Excessive thatch may be harboring the disease. 
  • The pathogen targets lawns that are low in nitrogen and nutrient deficient. 
  • Your lawn has poor access to sunlight
  • Drought
  • Excessive traffic
  • Low fertilization
  • Slow-growing lawns are highly susceptible to the disease. 

How to get rid of red thread

To get red thread out of your lawn, you’ll need to prioritize your lawn care routine and speed up your lawn’s growth. 

The conditions that likely made your lawn susceptible to red thread in the first place, such as low fertilization and sunlight, need to be corrected. By correcting your lawn’s fertilization regime and other lawn care practices, you can help make your grass more resistant to future infections. 

What about chemical control? Fungicides are available to control red thread, but they are usually unnecessary as long as you implement cultural measures. If you don’t prioritize lawn care maintenance, the disease is more likely to return. 

Ready to turn your pink lawn back to green? The following treatments will help restore your lawn’s health and get rid of red thread: 

  • Spread a light application of quick-release nitrogen fertilizer.
  • Water at the right time of day. Water the grass in the early morning before 10 a.m. so the lawn has enough time to absorb the moisture before the afternoon sun evaporates the water. Avoid nighttime watering; otherwise, you will create a moist environment that encourages pests and disease
  • Water less often and for longer periods. This watering technique promotes a strong root system. Watering too often and for short periods encourages a weak root system. 
  • Increase access to sunlight by trimming and pruning trees and shrubs. 
  • Limit heavy traffic on the lawn.
  • Apply lime to the lawn to maintain a soil pH between 6.5 and 7.
  • Collect grass clippings after each mow so that the disease doesn’t spread.
  • Dethatch the lawn.
  • Aerate compacted soil. When soil is compact, the lawn’s root system has little access to nutrients, air, and oxygen. Relieving compact soil with an aerator will help enhance your lawn’s growth and also improve drainage. 

How to prevent red thread in the yard

If you don’t want red thread crashing your backyard barbecue, you’ll need to maintain proper lawn care maintenance year-round. Skipping your lawn care chores might save you time, but it’s certainly going to reflect poorly on your lawn. 

Here’s what you can do to help prevent red thread from reoccurring:

  • Perform proper watering techniques that minimize prolonged leaf wetness. 
  • Remove excessive thatch.
  • Aerate compact soil.
  • Perform a fertilizer routine based on the results of a soil test. 
  • Allow enough space between new plantings, so your grass has enough access to sunlight. 
  • Minimize heavy traffic on the lawn. Installing walkways and patios is a helpful way to prevent foot traffic in the grass. 
  • Mow the lawn correctly and regularly. Poor mowing habits can put stress on your lawn. 
  • Overseed the lawn with grass cultivars that are resistant to red thread. 

How does red thread spread?

Unlike many other fungal diseases, red thread does not produce spores that will disperse to other yard areas. Instead, red thread infects healthy turf via mycelium growth and can survive unfavorable conditions by remaining dormant in infected grass.

What grass types are susceptible to red thread?

Your lawn is highly susceptible to red thread if you grow a non-resistant variety of Kentucky bluegrass, tall fescue, perennial ryegrass, fine fescue, or bentgrass. 

FAQ about turfgrass disease

1. How do I prevent turfgrass disease?

Red thread isn’t the only turfgrass disease that can blemish your lawn. The best way to keep your lawn fungus-free is to keep your yard well maintained. If you don’t show your lawn enough TLC, it may weaken and become more susceptible to fungal disease. 

The healthier your lawn, the more resistant it will be against fungus. Here are 15 lawn care treatments you can perform to help strengthen your lawn: 

Remove leaves and other debris from the yard. Lawn debris provides an excellent place for fungus to remain dormant. 
Mow the grass regularly (and correctly). Allowing your grass to grow too tall can make it vulnerable to lawn disease, especially snow molds. But mowing too low can stress the turf. It’s best to set the mower blades to your grass type’s recommended mowing height. And remember, never cut off more than ⅓ of the leaf blade during a single mow. 
Leave behind grass clippings. Grass clippings are beneficial for the lawn and needn’t be bagged and thrown away. Grass clippings act as a mulch for the lawn by maintaining moisture in the soil and adding nutrients. However, don’t let diseased grass clippings remain on the lawn. 
Perform proper irrigation practices. Water at the right time of day and less often. Watering less frequently for long periods promotes a healthy root system. Watering too often for short periods encourages a weak root system.
Invest in a sprinkler system. Not everyone wants to wake up at the crack of dawn to water their lawn. The easiest way to get more sleep and have your lawn watered is to install an automatic sprinkler system. 
Plant grass seed that’s disease-resistant and suitable for your lawn. Not all grass types are going to grow well on your lawn. Talk to a local lawn care professional about whether you should grow warm- or cool-season grass. Consider growing varieties that are disease-resistant.  
Test your soil. Performing a soil test can help you identify which nutrients your soil is lacking. The healthier your soil, the healthier your grass. 
Fertilize your grass. Your turf requires nutrients if it’s going to grow into a healthy yard. Fertilize the lawn with nutrients at least once a year so it can stay beautiful and healthy.  
Aerate compact soil. An aerator relieves compact soil by creating small holes in the ground. These holes allow water, nutrients, and oxygen better access to the root system. 
Remove thatch that exceeds ½-inch thick. Thatch is the dead organic matter that accumulates between the soil and turf. A thin thatch layer is good for the lawn, but a thick layer may harbor dormant fungus. 
Overseed the lawn. Keep your lawn dense and green with routine overseeding.
Remove existing weeds. Weeds invading the lawn can stress your turf. Why? Because the lawn must compete with weeds for space, sunlight, nutrients, and water. Remove the weeds either by hand or with a post-emergent herbicide. 
Apply pre-emergent herbicide. Pre-emergent herbicides help stop weeds from establishing in the first place. They are not an ideal herbicide for weeds that already exist in the yard. 
Control grubs and other pests. Grubs can weaken your lawn by munching on its root system. 
Spread compost across the lawn. Compost is an organic fertilizer that adds nutrients to the soil. You can rake a compost top dressing across the lawn or brew a compost tea and spray it on the lawn.  

2. What other turf diseases can infect my lawn?

When parts of the lawn begin to change color or texture, your grass is likely suffering from a fungal disease. Some mornings you might even wake up to mushrooms in the yard (thanks to the fairy ring disease).

Common turfgrass diseases include: 
Anthracnose
Brown patch
Dollar spot
Fairy ring
Gray snow mold 
Leaf spot and melting-out 
Pink snow mold 
Powdery mildew
Rust 
Summer patch 

3. What if I can’t identify the fungus on my lawn?

Correct identification of the fungus growing in your lawn is essential for effective control. If you misidentify the disease and apply the wrong control methods, those control methods may not be effective against the disease. As a result, the infection may worsen and potentially kill your grass. 

Sometimes a magnifying glass and field guide just isn’t enough. If identifying the fungus proves challenging, contact a diagnostic lab or turfgrass pathology lab for help. These labs are often located at state universities, and they specialize in diagnosing turfgrass diseases. 

Call in the pros for help

If there’s something weird growing in your lawn and it don’t look good, who ya gonna call? Lawn care pros. 

Treating and preventing lawn fungus is no easy task. It requires you to invest precious time into your lawn care routine, time that you could be spending on things you enjoy. Why spend the weekend removing fungus and watching your fun plans go down the drain? Hire a local lawn care professional to remove and prevent disease in your lawn. After all, they ain’t afraid of no fungus.

Main Photo Credit: Kris Lord | Flickr | CC BY 2.0

Jane Purnell

Jane Purnell is a freelance writer and actor in New York City. She earned her B.A. from the University of Virginia and enjoys a warm cup of French press coffee.