Pythium Blight

Pythium Blight

Type: Fungus, disease

Appearance: It starts out with small, circular patches of collapsed, water-soaked leaves and stems on close-mowed turf. Patches of cottony white mycelium may be visible in the morning. The infected turf dies and becomes matted.

Risk: Pythium blight is particularly damaging to creeping bentgrass, annual bluegrass, rough bluegrass, and perennial ryegrass. Outbreaks tend to start in low areas where more soil moisture is maintained.

Timing: It appears in the summer when dew periods are long and evening temperatures remain 68 degrees or higher.

How to Control Pythium Blight


Outbreaks usually occur in the same areas each year, so pay extra mind when preparing your yard for a healthy season. Do not add extra nitrogen to your lawn because the disease favors the nutrient. Plus, ensure your grass has proper drainage so roots are not waterlogged.

Maintaining a healthy turf can help stave off a pythium blight infestation. Tips include:

  • Water Well: Your grass needs adequate water to thrive. It prefers long soakings about two to three times weekly instead of daily watering, depending on the rain levels from the week.
  • Reseed patchy spots: Grass roots go deep into the ground and take up a lot of space, taking away the valuable real estate weeds need to thrive.
  • Aerate Your Soil: Soil compaction keeps air and water from reaching the deeper levels of soil where grass roots grow, so only plants that grow nearer to the surface, like weeds, can thrive.
  • Check Your Lawn’s pH Level: If your soil’s pH level isn’t neutral (about 7.0), your grass doesn’t have the right environment to thrive, but weeds might. To balance the pH level, your soil may also need applications of lime.


Pythium blight spread rapidly, so it’s important to get it under control as soon as you notice signs of the disease. In fact, large areas of grass can be killed in a matter of days! Fungicides are essential to control pythium blight. Be warned, however, that many other lawn diseases mimic pythium blight, and fungicides will not necessarily treat those lawn issues, so accurate diagnosis is key.

Shades of Green Lawn & Landscape knows just how to care for your lawn to prevent and treat fungal infections. And, if you’d like to have your best lawn year-round, we have a lawn care package for everyone’s needs and budget. Call us today at 765-771-9998 for a free quote.

Need Help with Pythium Blight?

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