Thatch can become a tightly interwoven layer of slowly decomposing grass stems, dead roots and debris that accumulates above the soil and below grass blades. A heavy layer of thatch provides a spot for disease spores to thrive and over-winter and can slow entry of water into the soil. Thatch restricts the movement of air and fertilizers thereby weakening the lawn and making it more disease prone. It can also absorb large amounts of fungicides when they are applied, helping to protect the disease from the chemicals. Correct compacted soil by aerating with a plugging tool that removes cores of soil.
Compacted soil can slow entry of water, causing water to either stand on the surface or run off.
This causes roots to dry out. Thin out branches or surrounding plants to let more light through and air circulate to lawn. This will facilitate the evaporation of water from leaf surfaces and the drying out of disease spores. It will also reduce the competition for nutrients from other plant roots in the soil. When a disease does infest your lawn or as a preventative treatment, you may need to use a chemical control.