Perhaps one of the most important factors that govern the amount of disease present in your home lawn is thatch. Thatch is a layer of partially decomposed leaves, stems and roots at the soil surface. This layer builds up over a period of several years. Thatch decreases the vigor of grass by restricting the movement of air, water, and fertilizers into the soil. Under heavy thatch conditions the roots are generally shallow which brings about increased damage from drought.
Diseases are usually much more severe in lawns with a heavy thatch.
You can reduce thatch accumulations by mechanical methods. De-thatching should be done in the spring or fall when grass growing conditions are best. Where you have a heavy thatch, it is best not to attempt to remove the entire thatch accumulation in one treatment. Recommendations on this web site do not endorse any commercial products or trade names.