Date of this Version
Causes, symptoms and treatment for pythium blight are covered here.
Pythium blight, sometimes called "grease spot" or "cottony blight," is no longer a disease of golf courses; it also is a serious problem in home lawns and other turfs. Caused by several species of Pythium fungi, the two most commonly associated with Pythium blight are Pythium aphanidermatum and P. graminicola. These fungi are in a group known as "the water molds," a group that includes Phytophthora and other pathogenic genera. They are referred to as "water molds" because they function best under wet, saturated soil conditions.
The Pythium species that attack turfgrass survive well in thatch, infected leaves and roots, and soil. These organisms are ubiquitous and capable of invading turfgrass leaves, crowns and roots from spring to fall.