Pythium Blight fungal spores germinate and spread during high temperatures between 80 to 90 degrees Fahrenheit and low temperatures between 55 to 65 degrees Fahrenheit. The disease overwinters in the yard and goes dormant when temperatures do not favor its germination. The disease can spread by walking across diseased areas, mowing diseased turf or leaving diseased grass clippings on the lawn. Spores can also travel through rainwater or irrigation runoff.
First small patches of water-soaked lawn that feel slimy and discolor when dry. Grass blades turn tan with a reddish tinge. Eventually, discolored grass areas may coalesce to create a large area of dead grass. In fact, large areas of the yard may die out when temperatures soar during the summer months. Treatment must be administered before the entire yard becomes infected with Pythium blight.
Prevent pythium blight from spreading to other areas of the lawn, using a fungicide. Spray these fungicides over the entire lawn. Dig up dead grass and replant those areas. Treat the fungal disease before replanting or your new seedlings can contract the disease. To prevent causing more damage, avoid spraying any fungicides on water-stressed lawns.
To prevent pythium blight from reoccurring, maintain a soil pH range that is neutral to slightly acidic. Check your soil's pH to make sure it is 6.0 to.7.3. Add lime to soil that is acidic, and add sulfur to the alkaline soil. Avoid using a fertilizer with high percentages of nitrogen, instead, use a balanced fertilizer.