Dollar spot forms hour-glass shaped lesions with reddish brown margins on Kentucky bluegrass and tall fescue. The lesions are often near the tip of the leaf on perennial ryegrass and creeping bentgrass, so the hour-glass is not as apparent. Pythium and brown patch are most often seen on annual bluegrass, perennial ryegrass, and creeping bentgrass in higher N areas, drainage swales, and other wet or humid areas. Pythium mycelium is a dirty white to gray and grows out of living tissue. Brown patch mycelium is not as common, but it is a grayish-brown color sunken down below the turf canopy.
Brown patch forms very irregularly shaped legions, with reddish brown margins.