Brown Patch

• Brown patch is the most common fescue fungus. As its name suggests, brown patch fungus causes brown patches in the fescue grass and then dies. It's most prevalent during humid weather and in lawns overfertilized with nitrogen. Prevent brown patch by switching to a low-nitrogen fertilizer and ensure the fescue grass receives proper drainage. Improve drainage by adding organic matter or putting in a ditch for water to accumulate.
  
  

Pythium Blight

• Pythium blight occurs on fescue grasses that are planted in high-humidity climates. When temperatures reach 86 degrees Fahrenheit or higher with night temperatures above 68 degrees and a relative humidity at 90 percent for more than a 14-hour time period, conditions for pythium blight are prime. High amounts of moisture, overseeding and overfertilizing also contribute to the fungus. Pythium blight causes patches of the fescue grass to rot and die. Because the disease spreads rapidly, prevention is the best control method. Avoid overfertilizing and overseeding, and water when the grass shows signs of drought.
  
  

Dollar Spot

• Fescue that forms round, white or brown spots the size of a silver dollar is infected with dollar spot. A closer look may show a white, fluffy-looking material on the grass. Warm days and cool nights help breed the fungus, as well as drought conditions and low fertility. Mow the fescue high to cut off the infected parts and bag the cuttings and dispose of them. Water the grass when it shows signs of drought such as wilting or rolling leaves. Apply a solution of liquid seaweeds and fish emulsion, which provides nutrition and helps strengthen the fescue to better fend off diseases.
  
  

Fusarium Blight

• Fusarium blight causes small reddish-brown patches that eventually turn yellow and pink fungal bodies at the crown of the grass. The fungus thrives in humid climates and spreads rapidly. Prevent fusarium blight by using low-nitrogen fertilizers and not adding nitrogen fertilizers in the spring. Water in the morning to reduce nighttime humidity levels and mow high to avoid stressing the grass. Don't allow thatch to accumulate to promote aeration.