Does your lawn have irregular shaped and sized dead or thin areas? These symptoms are usually caused by a complex of fungi which are present in the soil. Sodded lawns are usually affected by lawn diseases because of the stress which develops when the sod is forced to rooting down into our heavy soil. In most cases, seeded lawns don’t have problems with these particular lawn diseases.
Areas in the lawn which are dead or thin should be worked slightly with a garden rake and replanted with blue grass in sunny areas or creeping red fescue in shady areas. Replanted areas must be kept moist until the seed has germinated and is established. Fusarium resistance blue grass seed would be beneficial if available.
Your best bet in controlling these diseases, is to improve the general health of your lawn. If the thatch layer (dead grass) is over ½” deep, rake or use a de-thatcher to reduce or eliminate the thatch. Reducing the amount of lawn fertilizer applied each spring is also recommended. Watering practices must be changed. Use light frequent watering, to keep the top 1- 2 inches of soil moist. Watering is especially critical during hot weather, as the water applied during the day will help relieve both heat and drought stress. Aeration is also helpful for lawns which are infected with these diseases. The aerator takes cores of sod and soil out of the lawn and spreads them on the surface. This reduces soil compaction, improved water penetration and stimulates root development.
Response to any fungicide treatment has been mixed at the best. Improving the cultural condition of your lawn will reduce and eventually eliminate these disease problems.