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. Fungicides Fungicides are categorized as either systemic or non-systemic.
Systemic fungicides work from inside the plant and are usually the most effective.
However, they are very specific and will control only a narrow range of diseases. They control lawn diseases by coating the surfaces of the above-ground parts of grasses. Some of the fungicide will be removed after application by mowing, some washed from the leaves by rain and watering. There is also an eventual loss in effectiveness due to the degradation of the active ingredient. Fungicides must be applied periodically to keep new grass blades protected from disease.