red thread

Red Thread (fungal lawn disease)

What is Red Thread?

Red Thread is a fungal organism that causes patches of turf to turn brown and produce strands of red threadlike material. Red thread can be unsightly.  In most cases, the grass will recover just fine when the temperature cools in the fall.

Why do you have Red Thread?

It is normal for lawns to get a mild dose of red thread when conditions are optimal. Red Threat is really a symptom of one or more of the following: improper watering, poor grass, poor soil or all of the above.

Improper Watering

The fungus thrives when the surface of the soil lawn is wet and the roots are dry. Water on the grass blades will cause red thread to get worse.  Also, watering too often will cause the disease to get worse.

Solution to Improper Watering:  Don’t water more than every 3 to 4 days and make sure to water in the morning or early afternoon only…so that the grass does not stay wet all night. Also, one or more liquid aeration treatments will help the water move down into the soil and can make the disease less severe.

Poor Grass

Red Thread is most severe on Perennial Ryegrass…which is also susceptible to a lot of diseases (Rust, Dollar Spot etc.). Builders and landscapers plant a lot of Perennial Ryegrass because it sprouts quickly.  Homeowners often buy Perennial Ryegrass/Kentucky Bluegrass blend and seed it at a heavier rate than the manufacturer recommends.  If a little is good, a lot is better. Right? Wrong…the ryegrass takes over because it comes up faster than the bluegrass.  So even though they planted a blue/rye mix, they end up with a ryegrass lawn that is susceptible to Red Thread, Rust, Dollar Spot, Pink Patch etc. 

Solution to Poor Grass: If you have a lawn that is predominately Perennial Ryegrass, Red Thread and other diseases will always be a problem. We highly recommend Super Seeding in the late summer to get some different more resistant types of grass in your lawn.

Poor Soil

Newer lawns typically don’t have the most biologically active soil and are therefore subject to disease issues. The more biologically active your soil is, the fewer problems your lawn will have. 

Solution to Poor Soil: Fertilizing organically will gradually build soil biology and improve your soil and your lawns disease resistance. To speed the process,  consider a compost topdressing, liquid aeration, and/or traditional aeration.

What can you do now about Red Thread?

To help protect your lawn from Red Thread we recommend:

  • Don’t water more than every 3-4 days…only in the morning
  • Clean off your mower in between mowing…bag clippings for awhile if Red Thread is severe
  • Feed your lawn organically (so you don’t kill the good soil organisms that fight disease-causing fungi)
  • Add resistant grasses (Slice Seeding really helps)
  • Minimize your thatch layer and improve your soil with Liquid Aeration
  • Top-dress with compost in the fall to add beneficial biology
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