One of the most destructive turfgrass diseases. All grasses are susceptible to this attack, but it is most severe during hot or humid conditions. This type of disease can be a result of poorly drained soils, and can severely damage the roots and crown of grasses. Pythium blight usually appears as small spots or patches of blighted grass that appears to be water-soaked or greasy. Good water management and grass care and treatment are essential to keeping this disease under control.